able x
INCIDENCE OP CRETICAL AND NON-CRITICAL PATHOLOGY
"AMONG 1965 APPLICANTS BY AGE AND BODY SYSTEM

Tora
. Age Ae Ente Frequency of Incidence Rove Por
ody System SR ea a SSS GEESE _ Occurrence 10,000 Persap Ure
2
Cricical Path Freq yoo 285552 TH 8 1,929 2.8
Non-eritieal Path req os is? asa 327 2095 1655 213
otal Cell Frequency Pc a sae fet
Ears, Kose, Throat &
Critical Path Freq roo 2 3 6 so ° 7 2 36 0.7
Non-Cricteal Path Freq ab ak 85 300298 La 2,003 2517
Total Cell Frequency Ss a; 2059 26.4
Resoixatory
Beitieal Path Feoq - 1 3 5 2 6 4 3 1 st 0.6
Non-Crieteal Path Freq Pe: SY 7 OC 7 ae we
Total Cell Frequency Boo om se eo 8 369 6
cardiovascular
Geietcal Poth Freq Fe 1,396 17.9
Non-Critteal Path Freq woos ane SG SOB dw sear pies
Total cell Frequency 10 re 5 '599—«AOTS BGS 99262109 eres 6212
Apdosinet
Eeteical Path Freq Fn 7 5 on 48
Non-Ceitieal Bath Freq 139558 sot? 2284 186d 2yak 26735 8,612 nos
‘Total Cell Frequency ido 22592434992 149875695 6B 8966 use
levropeycblat
Erieical Path Freq Fe 7 3 1 269 35
Non-Cricteat Path Freq mes wD HB 5 2,140 2
Total Cell Frequency ba 6 203 me
ones_and_Jotnte
Eritical Fath Feeq a 1 “97 6.4
Non-Critieal Path Freq a5) ee tis 2) 33a 9H 7 1362 at
Total Cell Frequency pe Hy 2059 pany
Muscles
Eritical Path Freq sob mm BB 3 : : wr Le
Non-Critical Path Freq Se a 3 2 6 ts
‘Total Celi Frequency 5b 8 3 80 7 8 3 263 xa
collaneaus 6 2
Etieieal Path Freq 6 asa 2 a
Non-Ceitiesl path Freq ise 308 tos gaa sek Seam 34a
Total Cell Frequency Yeo 330s Sus O72 SAL 2S 080
‘TORAL
Teteteat pach Freq ise sols 555 691,055 9S st 2800 5,188 66.7
Non-Ceitical Path Freq G2 1,779 2,304 3,056,177 198 3,081 1,496 764 = 30080 20,983 265.6
Total Frequency for Age Group 822,«-2,180 2,815 3,611 3,826 5,263 3,996 2,013 1,044 401 200 26,171 33603
NOTES:

‘Age was computed a¢ of the date of first exanination during 1965 to last birthday and represents age at entry.

Incidence of disease is defined as the occurrence of pathology other than that recorded on the first examination during 1965, Critical and non-critical
codes are identified in the Appendix.

Row totale represent the incidence of pathology by body systen among all 1965 applicants, Only categories within a systen are mutually exclusive, t.e., critical,
Rey ott tal thas toe cotale for the wifterent ystems ave not additive dowward, Multiple incidence within a syaten is counted once according to category. The
Fou total for a system does represent airmen.

Cotuan totals represent the {neddence of pathology, regardless of system, by category, recorded since the first examination during 1965, by age interval, among
CTdes Soplicanes,, Individual column velues are not additive downward; hovever, colunn totals are additive across for incidence by category of pathology
Goring the interval, Column totals do represent airmen,

Source: Civil Aeromedical Institute, Aeranedical Certification Branch, Medical Statistical Section.

16



table IV

PREVALENCE OF CRITICAL AND NON-CRITICAL PATHOLOGY
"AMONG ATTRITION GROUP BY AGE AND BOUY SYSTEH

Age At Ente Frequency of © Prevalence Race
Body Systen ee EST ccurrence ter 1,000 Ademen
Etletcal rath Free wo L252 as rr a 1a ba
Non-crteccal Fath Freq 2 Wl sez 8S 3528 ans 3.0
otal Cell Frequency 252482 ats 35970 m2 18H 2700
Feeealence Rate per 1,000 27267 22.5 19.9 21D as 70 0 HSS aa
are, Nose, Throat 6 Mouth
Critical Path Freq 2 2 3 7 4 6 3 3 2 - 35 0.3
Non-Critical Path Freq Pens a St oR 4 360 1
Total Gell Frequency Pr er ec eS et} ees “ 995,
Prevalence Rate per 1,000 we 580 BL BH ONG Re SD 8.0
cspirato
Eritical Fath Freq nn : ‘ 2 4 “ 1 : - 26
Non-Critteal Path Freq oa en rd 8 7 8 sta
‘otal Celt Frequency rc rr rr  D ° 7 8 370
Prevalence Rate per 1,000 Pa
Etieteal Foe Freq Fe eS 7 28
NonsCritical Path Freq uses aS 609 RH 168
otal cell Frequency Fe 2/80
Total Celt Feegweney, og dS) apd Mase 1801662002298 25.0 TB 48B LD 6
Abdesinal
Critical Path Freq Fr OS) OS; 8 4 196 16
Non-Critscal Path Freq aay 659788 98D_ LMT 979549 XT TD 7185 sat
Total Cell Frequency, een B1S«1,005 1731358 10025603 7381
Total Cold FeeaueNey ogo 218 30-2 Heal 35.7 66.7 GOL 93,3 10.7 15,5129.7 18,7 39.7
opsyehistrie
Eeitical Fath Freq 7 9 Wo oe ss 8 2 : : 97 0.8
Non-Crittcal Path Freq oa 2082082] Kt 5 1,248 10:9
‘otal Cell Frequency baer CT 5 Tas
Prevalence Rate per” 1,000 O38 1) aT LB reo
es and Joints
Grieieal Paeh Freq Fe ° 2 608 a3
Non-Cetetcal Fath Freq 33700321226? SD 1,516 23
Total Cell Frequency Rok odessa 1956
Prevalence Rate per” 1,000 oO teed kD AT 206255 BS 269 LS ILD 13.8
Erieical rach Freq nr ee] A 7 1 2 7% 16
Non-Ceieseal Path Fee 5 7 3 ow oR 3 6 ? 1 2 1 n 06
Total Cell Frequency Fras re, a 8 3 3 206
Prevalence Rate per 1,000 ye ok OO LD PSD 20
Miscellaneous Condittons
Ee ee 8 2 pan Le
25) 463300893002 8K 7 2,322 18.8
Total Cell Frequency Fe Tt 25563
ree cer reer o00 2k he? 180A 20.2 LO HS 2,9 HLT LST 20.7
TOmAL
Erteteat Path Freq Pre a Ss 3,103 25.1
Ronseritteat eth Freq Be aoe 1,886 2,086 2,258 2,501 1737s 97218 15063 wir
seer eee rage Grup ‘1,046 2130327267 75400 2168521390 2,061,108 62279 AS 19,166
Prev. Rate for Age GrouP
pee 1,000 102.3 112.8 123.0 133.0 152.6 176.3 195.0 215.1 293.4 249.5 269.0 146.8
Wores:

‘Age was conputed a of the date of first examination during 1965 to last birthday and represents age st entry.

prevalence is defined as that pathology present on the firet examination during 1965. Critical and non-critical codes are identified tn the Appendix,

Atteteton includ
Genied subsequent to their examination in 1965.

Row totale represent the prevalence of pathology, by b
Critical, nonveritical, thus rov totale for the different systens are not
according to category,” The row total for a body systen does represent tree

Colman totals represent prevalence of any pathology regardless of system recor
column val
for prevalence of critical, non-erttss

‘ai, and total for the population, Column totals do represent airmen,

Soorce: Civil Aeromedical Institute, Aeromedical Certification Branch, Medics) Statistical Section.

10

those originally saved in 1965 whose most recent examination wae over 24 calendar months ago as of 1 January 1970; also,

fon the first examination during 1965 by age interval and category.
ae eee eencsbitive dowward; however, column totals do reflect prevalence of critical, non-critical, and totel for the age interval and are additive

{ecludes those

Ja, anong the attrition group, Only categories vithin a system are mutually exclusive, 1,0.
tive cowward, Multiple prevalence Within a systen or category 4s counted once

Individuel


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AIX ofdeL

20


PREVALENCE AND INCIDENCE OF DISEASE AMONG AIRMEN
MEDICALLY CERTIFIED DURING 1965

I. Introduction

Approximately 332,000 examinations for FAA
medical certification were performed during 1965
involving some 310,000 airman applicants (some
airline pilots are examined semi-annually). From
the total 310,000 airman applicants, 306,436
(99%) were medically certified during 1965.
This historical prospective study follows those
306,436 certified airmen from 1965 to 1970 to
observe prevalence of pathology at outset and the
incidence of disease among these airmen during
the study period. The study also considers pos-
sible contribution of medical factors to attrition
of airmen from an active status as a follow-up
to a previous FAA study! concerning character-
istics of airmen involved in attrition.

In addition, the study was designed to provide
quantification for questions concerning frequency
of examination by age, incidence of pathology
in relation to frequency of examination, and a
comparison of the attrition sub-group with the
still active airmen sub-group with respect. to
prevalence, incidence, and class of medical cer-
tifieate issued. Underlying these areas of
analytic interest was the need for basic descrip-
tive epidemiologic data for current and future
comparative use in appraisal of airman popula-
tion health status and program policy monitoring.

II. Source, Definitions, and Methods

A. Source and Definitions

Automated medical record files maintained by
the Aeromedical Certification facility in Okla-
homa City provided the source data for the study.
Automated historical files have been maintained
since 1962 on records dating back to 1959 for all
airman medical applicants. These files contain
examination data for the individual airman, se-
quenced by date of examination.

The year 1965 was chosen as the beginning
year for the study because of factors associated
with system stabilization. Computer system
implementation occurred during 1962, and prior
to 1965, automated procedures. code schedules,
and internal policies were subject to modifica-
tion quite frequently in connection with post-
implementation efforts. Some changes did, of
course, occur during the study period with regard
to policy on coding of disease conditions; how-
ever, the years 1965-1969 do represent the period
of greatest stability for study purposes.

In this study, a medically certified airman is
considered “active” for a maximum of 24 calen-
dar months following his most recent FAA med-
ical examination, i.e., regardless of the class of
medical certificate originally issued, it is valid for
third class airman purposes for a period of time
up to 24 calendar months unless otherwise limited
or recalled by the FAA, This definition results
in sub-groups for presentation and discussion
purposes consisting of the still active sub-group
(those airmen medically certified during 1965
whose most recent examination was during 1968
or 1969) and the attrition sub-group (those air-
men medically certified during 1965 whose most
recent examination was during 1965-1967), which
together comprise the total study group.

Much of the prevalence and incidence data
contained in the tables which follow differentiates
between critical and non-critical pathology.
While many diseases are potentially critical in
the mortality or morbidity sense, the Office of
Aviation Medicine has identified several which
are considered critical to the flight environment.
The primary consideration in the FAA defini-
tion of “critical” pathology is related to potential
of the disease for sudden incapacitation or in-
ability to respond to the flight environment.



Table XI

INCIDENCE OF CRITICAL AND NON-CRITICAL PATHOLOGY
AMONG AIRMEN STILL ACTIVE BY ACE AND BODY SYSTEM

oe
Age At Ente Frequency of Incidence Rate Woe
Body Syston E21 eS 10,000 Person Ye:
fae
Critical rath Freq 94920321920 ae asst 5s 2 11s 3.0
Non-Critical Path Freq 4 22th 3% 48 n 8 1398, 20.0
‘Total Celt Frequency 7753933805703 36 30 sos 430
Ears, Nose, Throat & Mouth
Grttteal Path Freq 1 : 1 ‘ 6 6 1B 7 7 A : 46 0.7
Non-Cri tical Path Freq Lok 213 263258866827 23 u 126 2b
Total Cell Frequency 32k 220268] 33 2% n um 25.3
Critical Path Freq : : 1 3 4 9 % ‘ 1 1 1 8 os
Non-Crttteal Path Freq oats 2 7 10 6 754 108
Total Cell Frequency 167 stor ask at 8 n 7 992 m3
Critical Path Freq 2 8 2 Cr nc a er? v 6 696 2.9
Non-Crittcal Path Freq U2 2972933627334 28 2 6 30 2,722 38.5
Total Gell Frequency NS 305325 ah 50788 59 36 Eat ta.8
Abdentnal
Critical Path Freq . 2 so ae e 6 a v 5 2 300 43
Non-Critical Path Freq 107455709 1,033 1,075 A381 1,204 60S 083k 7,228 Losi
‘Total Cell Frequency, 1oe 46873114073 En23 1631266 Os 7328 107.4
Critteal Path Freq 2 10 10 n Bas 10 4 1 1 : 90 13
Non-Critical Path Freq 53 156 200 22a 2h 8 2 8 2 1,596 nl)
Total Cell Frequency 56 Wet 210283 2th 2 9 2 1686 2010
Critical Path Freq 2 & ” on %8 6 8 27 7 : 406 5.8
Non-Critical Path Freq 2 gl 30 asks 28228 32 10 6 Lat 1e4
‘Total Cell Frequency 3310567238 % v7 6 te97 242
cles
Critical Path Freq son 9 1B wv 30 19 10 1 : - 9 a
Non-Crietcal Path Freq 1 ‘ M 2 3 19 vy 8 3 5 1 3 a3
Total Cell Frequency 4 1320 a 3048 3 ty i 5 1 210 ye
Miscellaneous Condsesong
Critical Path Freq sow B 50 5 20k 38 4 7 4 455 65
Yon-Critical Path Freq 94 e257 32g) ats 9 8 2,025, 2819
Total Cell Frequency, 98 21292801 26 2 23480 Ears
ome
Gritteat Pach Freq be a Ce 23 a67 52.4
Won-Grittcal Path Freq a2 1,367 1,992 2,532,514 343525138? 550k 7 163783 23955,
Total Frequency for Age Group 593 1,688 2,271 2,957 3,000 1693412714530 162730 20,454 219
vores:

‘Age was computed a8 of the date of first examination during 1965 to last birthday and represents age at entry.

Incidence of disease is defined as the occurrence of pathology other than that recorded on the first examination during 1965. Critical and non-eriticat codes
fare identified in the Appendix,

‘An airman is considered currently active if his most recent examination wat within the prucuding 24 calendar months as of 1 Janusey 1970 and was certified

45 meeting medical standards,

Row totals represent the inc{dence of pathology by body system aong almen still active a2 of I Janvary 1970, Only categories within 2 systen are gutually
exclusive, t.e., critical, non-critical, thus row totals for the different systems aro not additive dommvard, Multiple ineidence within @ aystus 18 counted
once according to category. The row total for a aystem docs represent airmen.

Column totals represent the incidence of pathology, regardless of system, by category, recorded since the [1rst examination during 1965, by age interval,
among atrmen still active as of 1 January 1970. Individual column values are not additive downward; however, column totale are additive across for incidence
by category of pathology during the interval, Colum totals do represent atemens

Source: Civil Aeromedical Institute, Aeromedical Cortiffeation Branch, Medical Statistical Section.

17



APPENDIX
CRITICAL MEDICAL CONDITIONS

Eye

Diplopia within 35° (homonymous, vertical

heteronymous)

Aphakia (absence of the lens)

Cataract (opacity of lens)

Glaucoma

Fails color signal test

Wears contact lenses

Blindness or absence of either eye (light per-
ception only)

Ear, Nose, Throat & Mouth

Mute
Deaf Mute

Cardiovascular

Myocardial infarction (heart attack, coronary
occlusion or thrombosis)

Coronary artery disease—heart disease, in-
cludes angina pectoris

Special heart pathology

Fibrillation (auricular)

Hypertension with heart pathology

Hypertension with medication

Abdominal
Complicated ulcer—bleeding, perforation, ob-
struction, severe pain
Neuropsychiatric

Brain
Vascular—thrombosis, occlusion, stroke, em-
bolism, aneurysm, spasm, hematoma, sub-
dural or epidural hemorrhage, CVA ete.

Convulsive Reactions—epilepsy, grand mal,
petit mal

Degenerative—atrophy, multiple sclerosis,
chronic brain disease

Spinal Cord

Degenerative—tabes, disseminated sclerosis,
ascending paralysis, amyotrophic lateral
sclerosis, etc.

Psychotic Disorders
Physical Condition)
Schizophrenia,
Major Affective Disorders
Paranoid States
Other Psychoses

Personality Disorders and Certain Other
Non-Psychotic Mental Disorders
A personality disorder that is severe
enough to have repeatedly manifested
itself by overt acts.
Chronic Alcoholism
Drug Addiction

Mental Deficiences
Mental Deficiency—congenital or acquired

(Not Attributed to

Miscellaneous Conditions

Diabetes, controlled by diet

Diabetes, controlled by insulin

Diabetes, controlled by hypoglycemic drugs
(other than insulin)

Collagenous Diseases

Neoplasm
Deformed by Amputation
Deformed by Limitation of Motion



Table XIIL

INCIDENCE OF CRITICAL AND NON-CRITICAL PATHOLOGY
1965 APPLICANTS VERSUS ATTRITION VERSUS AIRMEN STILL ACTIVE

Incidence Rate per 10,000 Person Years

Body System 1965 Applicants ‘Attrition Group ‘Airmen Still Active
Bye
Critical Pathology 24.8 40.5 23.0
Non-Critical Pathology 21:3 33:2 20.0
Total Pathology 46.1 73.7 43.0
Ears, Nose, Throat & Mouth
Critical Pathology 0.7 13 0.7
Non-Critical Pathology 25.7 35.7 26.6
Total Pathology 26.4 37.0 25.3
Respiratory
Critical Pathology 0.6 Ly 0.5
Non-Critical Pathology 118 aud 10.8
Total Pathology 124 22.8 13
Gardiovascular
Critical Pathology 17.9 90.3 a9
Non-Critical Pathology 44.3 93.5 38.9
Total Pathology 62.2 183.8 48.8
Abdominal
Critical Pathology 4.8 9.3 43
Non-Critical Pathology 110.6 178.5 103.1
Total Pathology 115.4 187.8 107.4
Neuropsychiatric
Critical Pathology 3.5 23.1 13
Non-Critical Pathology 27.5 70.4 22.7
Total Pathology 31.0 93.5 24.0
Bones and Joints
Critical Pathology 6.4 17 5.8
Non-Critical Pathology 20.1 35.0 18.4
Total Pathology 26.5 46.7 24,2
uscle.
Critical Pathology 1.9 3.6 7
Non-Critical Pathology 15 3.5 1.3
Total Pathology 31a ma 3.0
Miscellaneous Conditions
Critical Pathology 8.0 21d 6.5
Non-Critical Pathology 2 182.7 28.9
Total Pathology 52.2 203.8 35.4
TOTAL
Critical Pathology 66.7 195.7 52.4
Non-Critical Pathology 269.6 541.8 239.5,
Total Pathology 336.3 737.5 291.9

Source: Civil Aeromedical Institute, Aeromedical Certification Branch, Medical Statistical Section.

19



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incidence was lower than total study group in-
cidence in all instances, as was total (crude)
incidence of all disease for the airmen still active
sub-group (see Table XIII). When compared
with the total study group, total cause-specific
incidence rates were significantly different for
all but the ear, nose, throat and mouth disease
category which was not significant and for respi-
ratory disease which was significant at .10.

4. Incidence of Disease Among Airmen De-
fined as Attrition (Table XII). 77,514 person-
years were observed among airmen entering the
study and subsequently defined as attrition. Mis-
cellaneous conditions represented the highest total
cause-specific incidence category among the attri-
tion sub-group (203.8 per 10,000 person-years).
Abdominal (187.8 per 10,000 person-years) and
cardiovascular diseases (183.8 per 10,000 person-
years) were close seconds. Cause-specifie critical
pathology was highest for cardiovascular diseases
(90.3 per 10,000 person-years), Cause-specific in-
cidence was higher for all major body systems
and total (crude) incidence of all disease was
more than double the rates for either the entire
study group or the airmen still active sub-group
(Table XI). The attrition sub-group total
cause-specific incidence rates were all signifi-
cantly different from either the total study group
or the still active sub-group.

D. Most Recent FAA Examination and Pa-
thology Status

Table XIV shows that 80,366 members
(26.2%) of the study group provided no follow-
up information (see 1965 Subtotal). The re-
mainder of the study group provided one or more
years of observation with 148,560 (48.59%) pro-
viding observation data for the entire study
period, i.e, most recent FAA examination during
1969. Data in Table XIV contain only the
latest pathology status information differentiated
by critical and non-critical disease for the study
group as of the latest examination and, therefore,
do not necessarily reflect an accumulation of all
previous disease conditions. The latest pathology
status of those involved in attrition (most recent
examination prior to 1968) was worse overall
than those still active (see percentages “without
pathology” in Table XIV).

Critical pathology among the attrition sub-
group was also higher for those providing fol-
low-up medical data (latest examination 1966 or

1967 versus 1965). Critical rate comparisons
were significant for those attrition group mem-
bers providing follow-up (1966 and 1967) versus
still active airmen (1968 and 1969). Prevalence
of non-critical pathology decreased substantially
among still actives (4.5% versus 10.8% and
12.1%). Non-eritical pathology rate differences
were also significant for the attrition sub-group
versus still active airmen sub-group.

These findings, based on the latest pathology
status of study group members, paralleled find-
ings of the previous FAA report dealing with
medical contribution to attrition.! The previous
report contained prevalence data on a group of
airmen who were involved in attrition during
one year whereas, this report considers a three-
year contribution to attrition and latest examina-
tion pathology data. The more complete data
contained in this study have provided an im-
portant addendum, While it is still true that the
prevalence of critical pathology among airmen
still active is greater proportionally than that
among all attrition airmen when considered as a
single group, Table XIV also shows the impor-
tance of medical factors among those members
of the attrition group who did provide follow-up
examination data (latest examination 1966 or
1967). About two-thirds of the attrition group
did not provide follow-up and the latest pa-
thology status data suggested a lower preva-
lence of critical pathology than for either the
attrition group members who did provide follow-
up or the still active group, ie, 24% of the
applicants whose latest examination was during
1965 versus 3.9% for members of the attrition
group who did provide follow-up (latest exam-
ination 1966 or 1967) and 3.5% for the still ac-
tive group (latest examination 1968 or 1969).
Non-critical pathology is, of course, still greater
among the attrition group regardless of the com-
parison.

‘The conclusion to be drawn from these data is
that the prevalence of critical pathology among
all attrition group members is diluted by the low
prevalence for those who had only the one exam-
ination during 1965. When the attrition group
is sub-grouped by whether or not follow-up exam-
ination data were received, the importance of
medical factors as a possible reason for attrition
becomes more apparent for those 1,655 airmen
providing follow-up (see 1966 and 1967 Sub-
total).



appropriate method of dealing with the un-
knowns described above. Obviously, the most
compelling reason for selection of this method
is based on the observation that the study group
did not retain the same numerical strength
during the study period. Attrition from the
observation group confounds the task of inci-
dence computation, ie., denominator definition,
and does occur for varied reasons. The use of
person-years as the denominator for incidence
rate computations does not depend on the entire
study group being present for the total study
period, rather it takes into consideration the
number of persons under observation and the
duration of observation for each person.

MacMahon and Pugh suggest that “when fol-
low-up depends on a regularly scheduled exam-
ination and ascertainment of the outcome depends
on detecting a change in status between one
examination and the next, the most accurate pro-
cedure is to assume that persons lost to trace be-
tween two examinations were lost immediately
after the first examination.”? The reason for
such treatment of those lost to follow-up is ob-
vious. Since they cannot possibly contribute to
measured incidence during the interval, ie, a
positive outcome, they should not contribute to
person-years observed past the date of most re-
cent examination. Therefore, individuals lost to
follow-up in this study are considered lost im-
mediately after their most recent examination.
Because entrance dates varied for study group
members from 1 January 1965 to 31 December
1965, a mid-year entry date was selected as repre-
sentative for subsequent computation of person-
years. Applications are received in a consistent
manner throughout the year, particularly as con-
cerns the number received prior to mid-year
versus those received after mid-year.

Table I provides information on the year of
most recent examination for study group mem-
bers and the method for computing person-years
exposure.

Approximately 60% of the airmen in the orig-
inal study group were still active (using the study
definition of active airmen) as of the cut-off date
(31 December 1969) and thus provided 700,752
person-years of observation. The total study
group provided 778,266 person-years of observa-
tion; therefore, inactive airmen provided 77,514
person-years of observation.

Statistical significance at the .05 level was de-
termined for total cause-specific and total age-
specific rate differences on prevalence data and
for total cause-specific rates on the incidence data
(Tables IL, III, IV, X, XI, and XIJ—the third
cause-specific rate in the last column and the rate
in the last row). Statistical significance was not
determined for the cause/age-specific cell differ-
ences or critical/non-critical cause-specific or age-
specific rates; however, trends are noted as
appropriate. Methodology is described more
fully in reference 8; however, the technique
basically involves determination of the variance
of the difference between two rates; and subse-
quently, the standard error which is divided into
the difference between the two rates to arrive at
a critical ratio, which is used to approximate the
probability that the observed difference could
have occurred due to chance. The formula is as

follows:
Rate, (Ry) - Rate, (R2)
R R
cr=¥ 1 4 2
'N, (Observed “N. (Observed
Cases Cases
Group 1) Group 2)

Thus, if the difference between the two rates is
statistically significant at the .05 level, CR is
greater than or equal to 1.96. This methodology
was also used to appraise successive rate differ-
ences for disease incidence by frequency of exam-
ination and for rate differences on most recent
examination pathology status data. Potentially
meaningful significance at levels other than .05
are noted as appropriate.

Prevalence rates are expressed per 1,000 airmen
and incidence rates in terms of 10,000 person-
years in order to present meaningful non-frac-
tional rates for the latter. Rates were expressed
per 1,000 airmen for incidence of disease in
relation to frequency of examination data. Per-
centages were utilized for data dealing with most
recent pathology status for convenience of com-
parison,

Data presented are descriptive in nature with
numerous active versus attrition comparisons.
Reference to table footnotes is recommended for
further statements of methodology and data
limitations.



‘An extract listing of those medical conditions
defined by FAA medical personnel as “critical”
to the flight environment are provided in the
appendix. A complete listing of medical condi-
tions by code categories, as utilized by FAA
certification personnel, is available from the au-
thor on request. Many of the listed diseases are,
of course, critical regardless of the environment.
Others may appear less critical in the classical
sense; however, the unique FAA definition must
be recalled.

Federal Aviation Regulations, Part 67, specify
that a medical certificate will be denied if an
applicant has an established medical history or
clinical diagnosis of any of the following con-
ditions:

1. A personality disorder that is severe enough
to have repeatedly manifested itself by overt
acts.

2, A psychosis.

8. Alcoholism.

4, Drug dependence.

5, Epilepsy.

6. Disturbance of consciousness without satis-
factory medical explanation of the cause.

7. Myocardial infarction.

8, Angina pectoris or other evidence of coro-
nary disease.

9. Diabetes mellitus, requiring insulin or other
hypoglycemic drug for control.

However, certification is possible despite the
existence of one of the above disqualifying med-
ical conditions if exemption from the Regulations
is granted after extensive medical review by the
FAA and consultant specialists. The primary
considerations in such exemption cases are his-
tory, prognosis, and potential risk of sudden
incapacitation. From 1961 through 31 December
1972, a total of 1,051 airmen were granted exemp-
tions from FAR 67 of which 454 are still active.
It is appropriate to note, however, that airmen
with any of the nine disqualifying conditions
are often issued medical certificates with special
medical and operational restrictions that allow
for control of risk.

B. Methods

Initially, all applicants for medical certifica-
tion during 1965 were selected for the study but.

those denied certification on the first examina-
tion were subsequently excluded since they would
provide no possibility for follow-up experience.
‘A remaining total of 306,436 airmen were med-
ically certified at least once during 1965. Prev-
alence of pathology for the group was determined
as of the first certified examination received.
Incidence of disease and frequency of examination
were based on examinations performed subse-
quent to the first examination in 1965 through
31 December 1969. Incidence, of course, was
based on the occurrence during the study in-
terval of disease other than that recorded on the
initial examination (prevalence).

This study is not a classical cohort study of
individuals entering an observation group and
exposure category at a specified time and then
being followed forward. Exposure categories
are not defined as such and outcome is in terms
of all disease incidence. No follow-up to deter-
mine causes for withdrawal was possible and the
result is that one must deal with unknown biases
as a result of loss to follow-up among those con-
sidered as attrition. Death, voluntary withdrawal
for medical or personal reasons, economic factors,
and disenchantment with aviation are known to
be the major contributors to attrition.? Fortu-
nately, as concerns this study, medical factors
or death represent the least important reasons
for attrition or loss to follow-up in terms of rela-
tive contribution.

Loss to follow-up is a reality which must be
dealt with in most any cohort study. Theoret-
ically, loss to follow-up will affect the relative
rates for exposure categories only if it is su-
spected that bias exists with respect to exposure
category and outcome. As mentioned previously,
this study does not consider exposure categories
in the classical sense, e.g., those that smoke versus
those that do not smoke, etc. Outcome is meas-
ured in terms of incidence of some pathology
during the study interval. Obviously, some of
those lost to follow-up did develop pathology
subsequent to their most recent examination ;
however, from previous study results,’ it is felt
that outcome bias is minimal for those lost to
follow-up (or defined as attrition). Certainly,
data obtained for those that did provide follow-
up are valid with respect to outcome.

The person-years method for computing in-
cidence rates was determined to be the most


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16



with the higher frequencies of examination in
the middle age intervals. Mean age by frequency
of examination was somewhat erratic with mean
age exceeding the population mean age sporad-
ically. It appears from Table VI that frequency
of examination increases through the middle age
range and decreases toward both age extremes
for the total study group.

2. Age and Frequency of Examination for Air-
men Still Active (Table VII). Airmen still ac-
tive had a slightly higher mean age than the
total study group (36.0 years). Median age was
also approximately 36.0 years. Average fre-
quency of examination for airmen still active
was expectedly higher at 4.2 examinations for
the 5 year interval. Similar patterns to the total
study group were apparent for the distribution
of airmen still active with respect to age and
frequency of examination. It is interesting that
prevalence rates were uniformly lower for the
slightly older still active sub-group, since one
would empirically expect higher prevalence of
disease for an older group (see Table V).

3. Age and Frequency of Examination for
Airmen Defined as Attrition (Table VIII).
The mean age of airmen defined as attrition was
lower at 33.7 years than for the total population
or those airmen still active. Median age was
approximately 33 years. Average frequency of
examination for the attrition sub-group was
lower at 1.4 for the study interval. No important
differences from previously established distribu-
tion patterns were apparent with the exception
of the magnitude of the variables.

C. Incidence of Disease

1. Incidence of Disease by Frequency of Exam-
ination (Table IX). Cause-specific incidence of
disease generally increased with frequency of
examination, up to frequency of 6-7 examina-
tions, and began to decrease as frequency of
examination increased beyond that point. Ab-
dominal and muscle disease incidence continued
to increase through the higher frequencies of
examination, Miscellaneous disease conditions
showed a reverse pattern with incidence de-
creasing for greater frequencies of examination.
Incidence of all pathology was greatest for a
frequency of 6 examinations. When. successive
rates within a body system are compared, differ-
ences are significant for all comparisons through

the 6-7 frequency of examination level. Rela-
tively speaking, ear, nose, throat and mouth
pathology reflected the greatest increase with an
increase in frequency of examination. However,
more disease would be diagnosed in the abdom-
inal and cardiovascular areas in absolute terms.

These data are most informative even though
it is immediately apparent that much informa-
tion has been obscured by the combinations of
all classes and ages in Table IX. Age by fre-
quency of examination as reflected in Tables VI
through VIII does not suggest much in further-
ance of the interpretation. One would presume
that those with a greater frequency of examina-
tion (6—10+) were probably professional air-
men who would have been screened more
carefully and selectively prior to employment
to minimize future health problems. Certainly,
a detailed analysis of the age and class of med-
ical certificate relationship is called for in future
efforts.

2. Incidence of Disease Among All 1965 Cer-
tified Applicants (Table X). The total study
group provided 778,266 person-years of observa-
tion. Using this total as the denominator for
computation of incidence rates per 10,000 person-
years of observation, the data contained in Table
X was obtained. Total cause-specific incidence
of disease was highest for abdominal conditions
(115.4 per 10,000 person-years) among all 1965
applicants and second highest for cardiovascular
pathology (62.2 per 10,000 person-years). In-
cidence of cause-specific critical pathology was
highest for eye conditions (24.8 per 10,000 person-
years). No age-specific incidence data are avail-
able from Tables X through XIII since definite
data for derivation of person-years for the var-
ious age intervals are unavailable. Incidence
rates and frequencies for the major body systems
and all disease are available from Table X for
the study group.

3. Incidence of Disease for Airmen Still Active
(Table XI). The still active sub-group pro-
vided 700,752 person-years of observation Ab-
dominal pathology represented the highest total
cause-specific incidence rate for airmen still ac-
tive (107.4 per 10,000 person-years). Cardiovas-
cular disease was second highest (48.8 per 10,000
person-years) and eye conditions were highest in
the critical cause-specifie pathology category
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21



TECHNICAL REPORT STANDARD TITLE PAGE

Report No. 2. Government Accession No. 3. Recipient's Catalog No.

FAA-AM- 73-8

Title and Subtitle 5. Report Date

PREVALENCE AND INCIDENCE OF DISEASE AMONG AIRMEN April 1973

MEDICALLY CERTIFIED DURING 1965 6. Performing Organization Code
AAC-132

Author(s)

8. Performing Organization Report No.

Charles F. Booze, Jr., M. A.

Performing Organization Name ond Address 10. Work Unit No.

FAA, Civil Aeromedical Institute

Medical Statistical Section 11. Contract or Grant No.

P.O. Box 25082

Oklahoma City, Oklahoma 73125 13. Type of Report and Period Covered

Sponsoring Agency Name and Address
Office of Aviation Medicine

Federal Aviation Administration
800 Independence Avenue, S.W, 14." Sponsoring Agency Code
Washington, D. C, 20591

‘Supplementary Notes

Abstract
This historical prospective study follows some 306,000 airmen medically certified
ing 1965 through December 1969 to observe prevalence and incidence of disease
ng these airmen, It also considers possible contribution of medical factors to
rition of airmen from an active status as a follow-up to a previous FAA study
cerning characteristics of airmen involved in attrition. The study provides
atification for questions concerning frequency of examination by age, incidence of
aology in relation to frequency of examination, and a comparison of the attrition
-group with the still active airmen sub-group with respect to prevalence, incidenc
class of medical certificate issued. Basic descriptive epidemiologic data are

2 provided. Disease prevalence was highest for abdominal conditions among the

al study group. Prevalence of disease from all categories was highest for the
cition sub-group even though they were slightly younger than the still active sub-
1pe Frequency of examination was highest for the middle-aged applicants and cause:

cific incidence of disease increased with frequency of examination up to a frequen y

approximately one examination per year. Abdominal and cardiovascular diseases
resented the greatest incidence for the total study group and the still active

“groupe Miscellaneous conditions, i.e., skin diseases, endocrinopathies, allergies,

general systemic conditions,were slightly more important among the attrition sub-
wp. Overall, the attrition sub-group demonstrated the highest prevalence and

sdence of disease for the study period. However, 86% of the attrition sub-group
no recorded disease, thus diminishing the apparent importance of medical factors

1 primary motivator for attrition.

Sey Words 18. Distribution Statement

-rman Certification (Medical) Availability is unlimited. Document may
.sease, Prevalence and Incidence be released to the National Technical
-lots, Active and Attrition Information Service, Springfield, Virginia
tatistical Analysis 22151, for sdle to the public.

Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages | 22. Price
classified Unclassified

22 $3.00

DOT F 1700.7 (s-69)



Taste I

YEAR OF MOST RECENT FAA EXAMINATION
FOR ALL 1965 CERTIFIED APPLICANTS

Years Of
Year Frequency Percent Observation

80,366 26.2 0

6,498 2.1 1
35,508 116 2

122,872 39.9
85,504 11.6
= 148,560 48.5

oo

Still Active Subtotal -

184,064 60.1

Col. 2 a Col. 4
Person-Years

0
6,498
71,016

T7p14
106,512
594,240

700,752

Toran — 306,436 100.0 778,266
table 11
PREVALENCE OF CRITICAL AND NON-CRITICAL PATHOLOGY
"AMONG 1965 APPLICANTS BY AGE AND BODY SYSTEM
Fora
Age At Ente Frequency of Prevaienc:
ody Syston SBI GSB Le EG SS SST GOSS _Oceurrence __Per_ 1,000 4
Eye
Critical Path Freq roe 569499 GDS 3K 18D 4 5 35 3,393 L
Non-Critieal Path Freq foo 2593283770368 81 2 2B 21543, 1
‘otal Cell Frequency 3782882784)? 897 HBTS &6 58 51936
Prevalence Rate por 1,000 ay 18k B31 1BB AB 205223250 38.7 5049 r
Eats, Nose, Throat & Mouth
Critical Pach Freq 2 3 6 16 6 10 2 10 9 4 - n ‘
Won-Crieical Path Freq ee 202262358339 2K 1S 70 2 n 2,246
Total Cell Frequency se 2052687253934 18 9 26 n 29
Prevalence Rate per 1,000 Ee a oe eC
Respiratory
Critical Path Freq - ) : 9 5 7 w 8 2 : : 46
Non-Critical Path Freq 2% st ot 26 n 10 1,165
Total Cell Frequency 212% 69 28 n 10 vai
Prevalence Rate per 1,000 Ls 0 40h 2S PT 0B
Cardiovascular
Critical Pach Freq 2 18 a 49 et ee eT 80 6 2 107
Non-Critical Path Freq 2362) Stk 508509, 2943]. 207 10 60 36 3,876 1
Total Gell Frequency 256s 525K 5868S 7B RG 36 a6 43503
Prevalence Rate per 1,000 ved se? OSB BZ 2G 30.0 33,7404 1
Abdominal
Critical Path Freq 2 oa 3 69 oe 96 2 2 20 9 32
Non-Ceitteal Path Freq 369 1,222 1,737 2,268 2,684 3,402 2,529 1461977829250 16,905, 5
Total Cell Frequency 31 izes 177024342748 353024625 NebL BLS 17486
Prevalence Rate per” 1,000 ag ‘deci ‘391 (43.7 60,0 71,2 82,8 $8.6 1160 122,2139,6 5
Neuropsychiatric
Gritical Path Freq woo 25 an 39 43 36 6 ? 2 : 226
Non-Critical Path Freq Lbs 346 hOB HHL 559325 ATH co 8 10 2075
‘Total Cell Frequency ise 36) 368 40D 500, 602k 69 a 10 3,001
Prevalence Rate per 1,000 5285 Bl 82109 GTB BE
ones and Joints
Critical Path Freq vost 93 (zoe 35 B10 65 2 4 1,034
Non-Cricical path Freq 1073639532 S10 BL SAL 2B 125 2 20 3y391 1
‘Total Cell Frequency 1% le 658267979190 33 % 25
Prevalence Race per 1,000 737 8S ABB HALLS TL 20,8 BEL 1
Path Freq v8 48 os 1% 68 46 28 v 2 2 379
Non-Crieical Path Freq 7 a 7 2 18 a B 3 3 a wr
‘Total Cel! Frequency me 4B 6 o 96 86 67 a 20 5 3 526
Prevalence Rate per 1,000 he dS LT EBD
Miscellaneous Conditions
Critical Path Freq > oR 26 Pe en ee) ou 2 1 4 490
Non-crsescet Fath Freq oa a SO ae a 8 4,200, 1
‘Total Cell Frequency 38 jue S76 ISHED SST 2G 108 35 B 3690
Prevalence Rate per 1,000 Price Oe eA Oe CE 1
ona
Geteteal Path Freq 367227733 tOH GSD MHD 64 6,713 2
Non-Cricieal Path Freq 1,315 3,601 3,935 4,746 5,167,281 4,437 -2,238 to? 35 213 33,533, ue
‘otal Freq for Age Group Ties) 47323, 672 Si579 Gale 74445 5435924785 L490 875277 40,246
Prev. Rate for Age Group
per 1,000 96.6 VOL 103.1 123-9—138.5 150.2 168.9 BBL 21262252 243.2 n
NOTES:

‘Age was computed as of the date of first examination during 1965 to last birthday and represents age at entry.

prevalence {5 defined #2 that pathology present on the first exanination during 1965. Critical and non-critieal codes are identified in the Appendix.

how totals represent the prevalence of pathology, by body systen, anong all 1965 applicants. Only categories within a systen are mutvally exclusive, ie.»
aoe seers ceerereical, emus row totals for the different syatens are Rot additive downward, Multiple prevalence within a systen or category {# counted om

sicording to category.” The row total for a body systen does represent airmen,

coluan totals represent prevalence of soy pathology regardless of eysten recorded on the first examination during 1965 by age interval and category. | Indty:
cosa trees seeraet sdbitive downward, hewover, colunn totals do reflect prevalence of eritical, non-critical, and total for the age interval and are add

for prevalence of critical, nonceritieal, and total for the population, Column totals do represent airnen,

Source: Civil Aevonedical Institute, Aeronedical Cortification Branch, Medical Statistical Section?

8



E. Distribution of Attrition and Still. Active
Sub-Groups by Most Recent Class of Medical
Certificate

Tables XIV and XV provide further evidence
that attrition is due primarily to factors other
than medical. While Table XIV strongly sug-
gests that medical factors are an important cause
of attrition for those airmen who provided fol-
low-up examination data and could conceivably
have been important for those with non-critical
pathology, Table XIV also clearly indicates that
about 86% of the attrition sub-group had no
recorded disease and, therefore, probably no med-
ical factors motivating their attrition. Further,
one would not expect to observe the proportional
relationships found in Table XV if medical fac-
tors were primary contributors to attrition; in
fact, a reverse relationship would be anticipated
under such a premise since Class I applicants
must meet more vigorous medical standards. The
disproportionate findings with respect to class of
medical certificate last held for the attrition sub-
group versus the still active sub-group suggest
the importance of other factors as principal moti-
vators for attrition.

IV. Summary

Cause-specific prevalence of disease among the
study group was highest for abdominal condi-
tions. Eye conditions were the most prevalent
critical pathology. As expected, disease preva-

lence generally increased with age in total and
sub-group comparisons. However, disease preva-
lence was highest for the attrition sub-group even
though they were slightly younger.

Frequency of examination by age approaches
symmetry with the higher frequencies of exami-
nation in the middle age intervals, Cause-specific
incidence of disease increased with frequency of
examination up to a frequency of 6-7 examina-
tions during the 5 year interval and decreased
beyond that point. Abdominal and cardiovas-
cular diseases represented the greatest incidence
for the total study group and the still active sub-
group. Miscellaneous conditions, i.e., skin dis-
eases, endocrinopathies, allergies, and general
systemic conditions, were slightly more important
than abdominal and cardiovascular disease among
the attrition sub-group.

The attrition sub-group demonstrated the
highest prevalence and incidence of disease for
the study period. Findings of this study expand
data available through a previous FAA effort of
a similar nature to appraise the contribution
of medical factors to attrition While this re-
lationship between airmen involved in attrition
and still active airmen existed with respect to
disease prevalence and incidence, 86% of the
attrition sub-group still had no recorded disease,
thus diminshing the apparent importance of
medical factors as motivators for attrition. Class
of medical certificate data also suggest other
causes as principal motivators for attrition.

REFERENCES

1. Booze, C. F., Jr: Attrition From Active Airman Status
During 1970. FAA-AM-72-13, Office of Aviation
Medicine, Federal Aviation Administration, March
1972.

2. MacMahon, Brian, et al. Hpidemiologic Methods, Little
Brown, 1970.

3, Vital Statistics of the United States. Vol, I, pp.
28-29, U.S. Department of Health, Education, and
Welfare, Public Health Service, Washington, D. C.,
1950.

4. Fox, John P., et al. Hpidemiology, Man and Disease.
The Macmillian Company, 1970.



Ill. Findings and Discussion

Some explanatory comments are appropriate
before commencing a discussion of findings.
Conventional epidemiologic terminology and defi-
nitions‘ apply to the discussion which follows.
However, due to critical and non-critical cate-
gories within each body system, cause-specific
rates are broken down into critical cause-specific,
non-critical cause-specific, and total cause-specific
rates, Age-specific and age/cause-specific cell
frequencies are similarly broken down. Only
total rates were, however, computed for age-
specific and age/cause-specific cell data.

To reiterate, significance tests were performed
on total cause- and age-specific rates only. While
much useful information may be available from
the multitude of possible within-category-sig-
nificance comparisons, the interest in this study
centers on the overall relationship of total preva-
lence and incidence and the resulting impact on
attrition.

A. Prevalence of Disease

1, Prevalence of Disease Among All 1965 Cer-
tified Applicants (Table II). Total cause-spe-
cific prevalence was highest for abdominal
(esophagus and stomach, intestines, spleen, liver,
pancreas, gall bladder, and genitourinary and
gynecological) disease (57.0 per 1,000 airmen) ;
eye conditions were second highest (19.4 per
1,000 airmen). Age/cause-specifie total preva-
lence was also highest for abdominal conditions
(ranging from 21.9 to 139.6 per 1,000 airmen
as age increases) except for persons less than 20
years old, for whom eye conditions and miscel-
laneous conditions (skin, drugs, endocrinopathies,
allergies, and general systemic conditions) were
highest (both rates were 22.3 per 1,000 airmen).
Critical cause-specifie pathology prevalence was
highest for eye conditions for the total study
group (11.1 per 1,000 airmen).

As expected, age/cause-specific prevalence gen-
erally increased with age, with the exceptions of
neuropsychiatric and the miscellaneous condi-
tions. Prevalence patterns for the latter condi-
tions peaked earlier in the age distribution and
tapered off as age increased. Total age-specific
rates for all disease prevalence also increased
with age (last row).

2. Prevalence of Disease for Airmen Still Ac-
tive (Table TIL). Disease prevalence findings
among airmen still active as of 31 December

4969 cut-off date for the study paralleled findings
for the total study group. Some minor excep-
tions were noted in comparison of cell preva-
lence; however, cause-, age/cause-, and age-
specific prevalence rates were comparable with
respect to trend but lower than total study group
prevalence rates. Table V contains summary
rate data for the total study group and the still
active and attrition sub-groups. Total cause-
specific rate differences between the total study
group and the airmen still active sub-group were
significant except for ear, nose, throat and mouth
disease which was not significant and muscle
disease which was significant at the .10 level.
Total age-specific rate differences were significant
with the exception of age intervals greater than
55 years. Similar patterns were observed for
these older age intervals; however, the limited
number of observations resulted in statistical
non-significance. .

3. Prevalence of Disease Among Airmen De-
fined as Attrition (Table IV). Disease preva-
lence findings for the attrition sub-group paral-
leled findings for the total study group. Cause-,
age/cause-, and age-specific rates were compa-
rable with respect to trend but were higher than
either the total study group prevalence rates or
the airmen still active prevalence rates (see Table
V). Total cause-specific rate differences between
the total study group and the attrition sub-group
were significant except for the ear, nose, throat
and mouth disease category which was sig-
nificant at .10 level. When attrition versus still
actives were compared, both total cause-specific
and total age-specific rate comparisons indicated
significant differences for all but one age-specific
category (greater than 65 years). Total age-
specific rate differences for the total study group
and the attrition sub-group were significant ex-
cept for the less than 20 years interval. The
55-59 and 60-64 age intervals were significant at
-10.

B. Age and Frequency of Examination

1, Age and Frequency of Examination for All
1965 Certified Applicants (Table VI). The
mean age of all 1965 certified applicants selected
for the study was 35.0 years. Median age was
also approximately 35.0. Average frequency of
examination for all study group members was
3.1 for the 5-year interval. Average frequency
of examination by age approached symmetry


‘Table XIE

INCIDENCE OF CRITICAL AND NON-CRITICAL PATHOLOGY
‘AMONG ATTRITION GROUP BY AGE AND BODY SYSTEX

er
Age At Entry Frequency of Incidence Rate Por
Rody Systen IE IE EES TS_ “Occurrence _ 10,000 Person Yr
xe
Exicicat path Freq an so 3 w wv 6 6 316
NonsGritical Path Freq Fr re rr 3 2% 10 3 5 257 33.2
Total Cell Frequency “6? at 37 0 38S 3900 rr uw sn 73.7
Ears, Nose, Throat & Houth
Critical Path Freq : 1 1 1 . 2 2 2 + 1 + 10 13
Non-Critseal Path Freq $0 36 a ess von 1B 2 3 27 337
Total Cell Frequency, 5 OR 7 383 3B 15 3 3 287 37.0
espica
Critical Path Freq : . : - 1 3 2 2 3 2 : Bb 17
Non-Ceieical Path Freq 5 ow wo iB OR 38 2 0 6 a 164 a
Total Cell Frequency 5M 6 6 23 7 BoB 8 1 m7 nis
Cardiovascular
Critical Path Freq 14 now n 700 50.3
Non-Crieteal Path Freq 3 MTL 8 ro 75 3305
‘Total Cell Frequency OBO 38HS283 82H 5080 1,425, 183.8
Abdominal
Critical Pach Freq - 4 6 5 7 v Bow 5 2 3 n 93
Non-Ceitical Path Freq 52 100=adsa#C“‘ié‘és:= QDMA 8 3 1,386 178.5,
Total Cell Frequency 3 toe 28S 226289239 6 1456 1e78
Critical Path Freq poo a n nr nes ” 6 “ L 19 aa
Non-Crietcal Path Freq wR 38 BF rr re 16 4 3 546 70:4
Total Cell Frequency 5a SC 8 4 ns 9303
jones and Joint
Eritical Path Freq 1 5 7 2 6 BOB ? 2 5 1 on 7
Non-Crieteal Path Freq we BH sr ed % 4 1 an 35.0
Total Cell Frequency Fr a: a wo 16 8 2 362 467
wesc
Critical Path Freq 2 1 6 6 : 2 : - 28 3.6
Non-Critical Path Freq 2 1 3 ‘ 6 ‘ 2 1 3 1 27 35
Total Cell Frequency 3 4 1% 10 2 3 3 i 33 Ta
isceltaneous Conditions
Critical Fath Freq 2 5 un ww 16 9 3 5 164 erat
Non-ritieal Pach Freq om aH Boon 7 1,416 182.7
Total Cell Frequency e223 588626308235 m2 11580 203.8
‘TOTAL
Eriticat path Freq Pome > OS 1,507 195.7
Non-Crseteal Path Freq ae at2 S24 6383 S66 309M 43200 5418
‘Total Frequency for Age Group 22949254 SK RG, 8828128 70 3,717 73765

ores:

‘Age was couputed as of the date of first exantnation during 1965 to La

birthday and represents age ar entry.

incidence of disease is defined as the occurrence of pathology other than that recorded on the first exaatnation during 1965. Critical and non-criticel codes
are identified in the Appendix.

cAterition includes those originally Lenved in 1965 whose most recent examtnation was over 24 calendar months ago as of 1 January 1970; aléo, includes those
denied subsequent to their examination in 1965.

nov totale represent the incidence of pathology by body systen anong the attrition group. Only categories within s syaten are sutually exclusive, 16,1
Row fotle rerrettical, thus tov totale for the different syotens are not aéditive downward, Multiple incidence within « system ts counted once according
fo category, The cow total for 2 systen does represent airmen,

column totals represent the incidence of pathology, regardless of aysten, by category, recorded since the first examination during 1965, by age interval,
coe eter ecitlon groups, Individual column valucs are not additive gomwerd; however, colum totsls are additive across for incidence by category of
pathology during the interval, Colum totals do represent airmen.

Source: Civil Aeromedical Institute, Acrmedical Certification Branch, Medical Statistical Section.

18







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ACKNOWLEDGEMENT

The author wishes to express appreciation to Richard H. Rice of the
Medical Statistical Section, Civil Aeromedical Institute, and Dr. Paul S.
Anderson of the O. U. Medical School, Department of Biostatistics and
Epidemiology, for their comments and suggestions. Appreciation is also
extended to Shirley Dark and Judy Toberman for their assistance in data
accumulation and preparation of this study.







Table 111
PREVALENCE OF CRITICAL AND NON-CRITICAL PATOLOGY

AMONG AIRMEN STILL ACTIVE BY AGE AND BODY SYSTEM.

Age At Ente Frequency of Prevalence Rate

Rody Syste S20 DORE F529 9G HIGGS FOO B5__occurrence per 1,000 Adtmer
Be
Critical Pach Freq se 72am ew Bon 4772 9.7
Nou-Crittcal Path Freq 7 Me tes 2828208 20 3 irs m8
Total Cell Frequency 125 ue? asa 528 taht 34 31196
Prevatence Rate per 1,000 1.7 16.9 15.3158 1k 16.2.9 e699 5

Nose, Throat & Mouth
Critical Path Freq : A 3 7 2 ‘ ° 3 ‘ 2 : 38 0.2
Nou-Crittcal Path Freq 135 ask ws 10 7 1,286 ro
Total Cell Frequency, 19538 ats 203 ages 2 7 1326
Prevatence Rate per 1,000 28 37 5A 73 7.2 BS 0? ewe 12
Respiratory
Critical Path Freq : : 5 3 3 4 4 1 : : 20 on
Non-Critical Path Freq n 8 seas 2 18 4 2 el 34
Total Cell Frequency u Cee ee a it ‘ 2 ea
Prevalence Rate per” 1,000 16 B20 38 6S ww 35
Gardtovascolay
Gritteat Path Freq 1 6 3 2 wt ns 38 n 3 354 2.0
Noo-Crieical Path Freq % 261-268 25k 293369 ask 10g 2 2,049, ne
Total cell Frequency % 267 77 oss 382 8st u 2,003
Prevalence Rate per’ 1,000 M2130 10,3 1.112.037 15,8 20.2 2k 258 a8 13.2
Abdaninal
Critical Pach Freq 1 ° bw 33 ae Bas 19 2 3 325 Le
Non-Crittcal Path Freq iso 363 gu 1438214542 2,086 14950 ge) 9,760, 334
‘Total Cell Frequency. 17372956 sta ys732fU72 leas Sok weed 25 10,085
Prevalence Rate per 1,000 21.9 27.9 35,6 6.25.8 6.873933 node 55.2
leuropsychta
Critical Path Freq so 1% 23 7 5 2 : 129 7
Non-Criticat Path Freq Ss? zk 75892533 3 5 1,427 x
‘otal Cell Frequency Ce Cc 7 338206, a 3 n 5 1,556
Prevalence Rate per 1,000 BL 6370 70881 85
ones and Joints
Critical Path Freq om n swan Comer 13 2 396 3.2
Won-Crittcal Path Freq 46 163 sh 243278306 % 16 4 1,875 10.3
‘Total Cell Frequency 32 7236 31e 367 5870s St? 29 6 zur
Prevalence Rate per” 1,000 18 91 BB 10.2 3018.38.92? 20.2. 135
Critical Path Freq 6 Bp 2 2% at 27 w 10 1 : 205 La
Non-Crittcat Path Freq 2 0 2 Bb 5 10 ° re 6 2 1 : 25 04
Total Cell Frequency 125 3 aa 30 ae 26 2 2 > 280
Prevalence Rate per 1,000 MS 2 3 oe? stoke : Ls
Miscellaneous Conds tions
critica - 6 Bb 8 Boss ot 26 10 6 1 249 13
Non-Critceal Path Freq ais 2622502987299 aaa a7 2 5 2 1,878 10:3
‘Total Cell Frequency Ns 278263 326330334283 38 nu 3 227
Prevalence Rate per 1,000 W636 9.8 105 9a aw we
ort
Critica Pach Freq os 30056 ag? sats g59 st 3 36 3,610 13.8
Non-Critteal Path Freq asl 1,520 2,049 2,692 2,909 3,780 2,700 1,361 60a 3 185470 ror
Total Freq for Age Group 585 1y820 2,405 3/179 Baan 45331259 L677 Bab 288 as 22,080
Prev. Race for Age Group
per 1,000 87-3 88.9 89.5 102.8 121.5 196.6 155.6 179.6 199.2 206.1 2178 120.9
nores:

‘Age was computed as of the date of first examination during 1965 to last birthday and represents age at entey.
Prevalence { defined ay that pathology present on the first examination during 1965.

‘An airman {s considered currently active {£ his gost recent exaai

a5 weeting medical standards.

Row cotal
critical,

once according to category.

Column cotals represent prevalence of a
column values are aot additive dowuard, however

for prevai

Source;

18 represent the

ny pathology regardless of system recorded on the first
‘colun totais do reflect prevalence of critical

ence of critical, non-critical, and total for the population.

Civil Aeromedical Institute, Aeramedical Certififeation Branch, Medical Statistical Sections

valence of pathology, by body systen, among atrmen still active.
honverstical, thus row totale for the different systeas are not additive dowward,
The row total for a body system does repr

Critical and non-eritical codes are i

ntitied in the Appendix.

ination was vithin the preceding 24 calendar months as of 1 January 1970 and wes certified

Only categories within 9 systen are autually exclusive, f.e.,
Multiple prevalence within a systes or category 1s counted

‘Colunn totais do represent airmen.

cannation during 1965 by age interval and category. Todividual
» nonveritical, and total for the age interval and are additive



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