Department  of Health and Human Services 
OFFICE  OF 
INSPECTOR  GENERAL 
DRG  79 VALIDATION STUDY  UPDATE: 
RESPIRATORY INFECTIONS  AND 
INFLAMMATIONS 
e  . 
FEBRUARY  1993  OFFICE  OF  INSPECTOR  GENERAL 
The  mission  of the  Office  of Inspector  General  (OIG),  as mandated  by Public  Law 95-
452, as amended,  is to protect  the  integrity  of the  Department  of Health  and  Human 
Services  (HHS)  programs  as well as the  health  and  welfare  of beneficiaries  served  by 
those  programs.  This  statuto~  mission  is carried  out  through  a nationwide  network  of 
audits,  investigations,  and  inspections  conducted  by three  OIG  operating  components: 
the  Office  of Audit  Services,  the  Office  of Investigations,  and  the  Office  of Evaluations 
and  Inspections.  The  OIG  also informs  the  Secretary  of HHS  program  and 
management  problems  and  recommends  courses  to correct  them. 
OFFICE  OF  AUDIT  SERVICES 
The  OIGS Office  of Audit  Services  (OAS)  provides  all auditing  sewices  for HHS, 
either  by conducting  audits  with its own audit  resources  or by overseeing  audit  work 
done  by others.  Audits  examine  the  performance  of HHS  programs  and/or  its 
grantees  and  contractors  in carrying  out  their  respective  responsibilities  and  are 
intended  to provide  independent  assessments  of HHS  programs  and  operations  in 
order  to reduce  waste,  abuse,  and  mismanagement  and  to promote  economy  and 
efficiency  throughout  the  Department. 
OFFICE  OF  INVESTIGATIONS 
The  OIGS Office  of Investigations  (01)  conducts  criminal,  civil, and  administrative 
investigations  of allegations  of wrongdoing  in HHS  programs  or to HHS  beneficiaries 
and  of unjust  enrichment  by providers.  The  investigative  efforts  of 01  lead  to criminal 
convictions,  administrative  sanctions,  or civil money  penalties.  The  01  also  oversees 
state  Medicaid  fraud  control  units which  investigate  and  prosecute  fraud  and  patient 
abuse  in the  Medicaid  program. 
OFFICE  OF  EVALUATION  AND  INSPECITONS 
The  OIGS Office  of Evaluation  and  Inspections  (OEI)  conducts  short-term 
management  and  program  evaluations  (called  inspections)  that  focus  on issues  of 
concern  to the  Department,  the  Congress,  and  the  public.  The  findings  and 
recommendations  contained  in these  inspection  reports  generate  rapid,  accurate,  and 
up-to-date  information  on the  efficiency,  vulnerability,  and  effectiveness  of 
departmental  programs. 
Amy L. Lockwood  of BOTEC  Analysis  Corporation  prepared  this report  with 
direction  from  Janet  W. Knight,  BOTEC  Project  Director,  and  David  C. Hsia,  OIG 
Project  Officer.  Contract  information  and  project  participants  are  listed  in Appendix  1 
to this inspection.  Department of Health and Human Services 
OFFICE  OF 
INSPECTOR  GENERAL 
DRG 79  VALIDATION STUDY  UPDATE: 
RESPIRATORY INFECTIONS  AND 
INFLAMMATIONS 
FEBRUARY  1993  OEI-12-89-00193  EXECUTIVE  SUMMARY

PURPOSE 
This  inspection  reabstracted  on a blinded  basis,  the  International  Classification  of 
Diseases,  Ninth  Revision,  Clinical  Modification  codes  from  a sample  of Medicare 
discharges  billed  as diagnosis-related  group  (DRG)  79:  Respiratory  infections  and 
inflammations.  It compared  the  reabstracted  DRG  to the  hospital-billed  DRG  for 
reimbursement  changes.  The  sample  was nationally  representative  and  covered  all of 
1988, the  most  recent  data  available. 
This  inspection  updated  a previous  Office  of Inspector  General  (OIG)  study.  For 
1985, the  OIG  found  18.4 percent  errors  among  74 reabstractions,  improperly  over-
reimbursing  hospitals  by a projected  $28.4 million.  This inspection  used  a parallel 
methodology  to make  these  studies  statistically  comparable.  Statistical  tests 
determined  whether  numeric  differences  between  1985 results  and  1988 results  were 
real  (statistically  significant)  or could  be  attributed  to random  error. 
FINDINGS 
DRG  79 bihg  emr  redhced 
Of  123 discharges  reabstracted  for this inspection,  11 (8.9 percent)  were  incorrectly 
assigned  to DRG  79.  This was a statistically-significant  improvement  over  the  18.4 
percent  error  rate  for DRG  79 in 1985.  This  rate  also significantly  differs  from  the 
14.7 percent  errors  for all discharges  in 1988. 
Financial impact  of DRG  79 billikg emor not redh.ced @nificantZy 
This inspection  projected  that  discharges  incorrectly  assigned  to DRG  79 over-
reimbursed  hospitals  $22.7 million.  This  result  did not  significantly  differ  from  the 
$28.4 million  over-reimbursement  in 1985.  The  increase  in the  number  of DRG  79 
bills in 1988 offset  the  decrease  in the  proportion  of errors. 
i  TABLE  OF  CONTENTS 
EXECUTIVE  suMMARY 
INTRODUCTION  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  1 
FINDINGS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...4 
S Errors  reduced  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  4 
Most  errors  over-reimbursed  hospitals  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  4 
 
Hospitals  still over-reimbursed  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  4 
 
ENDNOTES  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  6 
   
AGENCY  COMMENTS  7 
  .0..0.  .  .  .  .  .  .  .  .0.,...  .  .  .  .  .  .  .  .0...00  .  ..00..  .0 
APPENDICES 
f%  Project  participants  . . . . . . . . .  A-1 
..0..0  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  ...0  .  .  .  .  .  .  . 
B:  ICD-9-CM  procedure  codes  in DRG79  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  B-1 
c  Sample  representativeness  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  c-1 
D:  DRG79billing  errors,  1985 and  1988..  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  D-1 
E.  DRG79case-mix  index  change,  1985 and  1988  . . . . . . . . . . . . . . . . . . . . . . .  E-1 
F:  Reasons  for DRG79errors,  1985 and  1988 . . . . . . . . . . . . . . . . . . . . . . . . . .  F-1  INTRODUCTION 
Background 
Diagnosis-related  group  (DRG)  79:  Respiratory  infections  and  inflammations; 
includes  168 International  Classification  of Diseases,  Ninth  Revision,  Clinical 
Modification  (ICD-9-CM)  codes.  These  ICD-9-CM  codes  identi~  infectious  diseases, 
particularly  tuberculin  bacillus  exposure  or tuberculosis  infection,  as well as anthrax, 
mycobacterial  infections,  empyema,  abscesses,  and  similar  infectious  conditions. 
Tuberculosis  incidence  had  decreased  with improved  standards  of living and  the 
advent  of antibiotics.  It has recently  become  endemic  again,  primarily  in immigrant 
and  homeless  populations.  This resurgence  may  also affect  Medicare  beneficiaries. 
DRG  79s weight  increased  from  1.7795 in 1985 to 2.0777 in 1988.  Since  1985, the 
Health  Care  Financing  Administration  (HCFA)  altered  DRG  79 to eliminate  age 
over  69 as a complication  code  and  created  DRGs  474 and  475 for ventilator-assisted 
patients.  These  changes  shifted  billings in one  quarter  of the  data  collection  period 
for this inspection. 
In a previous  study, the  OIG  found  that  DRG  79 had  a disproportionately  high 
proportion  of billing  errors.1  Correct  ICD-9-CM  coding  would  have  grouped  18.4 
percent  of its 74 reabstractions  to different  DRGs  in 1985.  These  billing  errors  over-
reimbursed  the  hospitals  a projected  $28.4 million. 
This  inspection  updated  the  previous  study using  1988 data,  the  most  recent  available. 
It used  a parallel  methodology  to make  these  inspections  statistically  comparable. 
Methodology 
This inspection  randomly  selected  123 DRG  79 discharges  from  26 hospitals.  The 
study population  consisted  of 102,561 Medicare-reimbursed  DRG  79 discharges  during 
Calendar  Year  1988.  The  design  excluded  discharges  from  specialty  institutions  such 
as childrens  hospitals,  tuberculosis  units,  and  psychiatric  facilities.  It also  excluded 
discharges  in Maryland  and  New Jersey,  which the  PPS  still exempted  in  1988.  Finally, 
it excluded  bills for pediatric,  obstetric,  and  psychiatric  DRGs  (principally  drug  and 
alcohol  rehabilitation  performed  by a general  hospital).2  Unlike  its 1985 predecessor, 
it included  hospitals  established  since the  advent  of the  PPS in  1983. 
The  OIG  requested  that  hospitals  send  complete  copies  of the  sampled  medical 
records  to the  OIGS contractor,  Baxter-Health  Data  Institute  (HDI)  of Lexington, 
MA.  The  OIG  followed-up  missing records  and  issued  subpoenas  to compel  the 
cooperation  of four  hospitals. 
The  OIG  contracted  with the  American  Medical  Record  Association  (AMR~  now 
named  the  American  Health  Information  Management  Association,  or AHIMA)  to 
1  reabstract  the  charts.  The  AMRA  selected  ICD-9-CM  codes  supported  by the  record, 
determined  the  principal  diagnosis,  and  grouped  to select  the  correct  DRG.  To  assure 
that  the  original  ICD-9-CM  codes  and  DRGs  did not  affect  the  reabstraction,  the 
AMRA  coders  conducted  their  work without  knowledge  of the  original  ICD-9-CM 
codes  and  DRGs.  The  coders  had  instructions  not  to treat  marginal  problems  or 
honest  differences  in judgment  about  appropriate  coding  as DRG  errors.  This 
standard  should  have  produced  a conservative  estimate  of the  proportion  of discharges 
having  DRG  errors.  A series  of reliability  checks  verified  the  reproducibility  and 
accuracy  of the  AMRA  coding.  The  AMRA  also identified  the  reasons  why a 
hospitals  bill differed  from  the  correct  codes. 
BOTEC  Analysis  Corporation  of Cambridge,  Massachusetts  (BOTEC)  edited  the 
AMRA  database,  checked  the  samples  representativeness,  and  conducted  statistical 
analyses  of the  correlates  and  financial  consequences  of DRG  79 miscoding.  It also 
reweighted  the  1985 data  to improve  comparability  with this inspection.  Statistical 
tests  determined  whether  numeric  differences  between  1985 results  and  1988 results 
were  real  (statistically  significant)  or could  be  attributed  to random  error. 
Representativeness 
The  sample  generally  resembled  the  underlying  population  of DRG  79 bills with 
respect  to hospital  and  patient  characteristics.  The  one  exception  to this was the 
distribution  of the  sample  with respect  to hospital  size.  [Appendix  C]. 
2
 Bed size  Teachingstatus 
reteaching 
Nonteating 
sample  Population  Sample  Population 
Location  Control 
Me@@ltan 
-w_ 
(a 
n 
(2 
u 
u 
Nonprofit Nonprofit
sample  Population  sample  Population 
Figure  l:  DRG79sample  representativeness  byhospital  demography,  1988 
Age  Sex 
65-74  Male 
65-74  Male 
75-84  75-84 
+  Female 
Female 
Sample  Population  Sample  Population 
Race 
Q  @;~ 
Sample  Population 
3  FINDINGS 
Errors  reduced 
Peflferit 
Of the  123 sample  discharges,  11 (8.9 
percent)  were  incorrectly  assigned  to 
20 
DRG  79.  This  significantly  improved  1 
upon  the  18.4 percent  error  rate  in  15   
1988 
1985.a  Small  hospitals  billed  more 
10 
accurately  than  in 1985, and  bills for 
patients  less than  65 years  old, and  aged 
5 
75-84, were  more  accurate  than  in 1985. 
[Appendix  D].  0[ 
DRG 79  All DRGs 
The  improvement  in accuracy  in DRG 
79 differed  significantly  from  the  Figure  3: Proportion  of  DRG  79  and  all 
improvement  in all DRGs  from  1985 to  co&ng errors;  1985 &  1988 
1988, from  20.8 percent  in  1985 to  14.7 
percent  in 1988.  This  inspections  8.9 percent  DRG  79 error  rate  also  differed 
significantly  from  the  14.7 percent  of errors  in all DRGs  in  1988.3 
Most  errors  over-reimburse  the  hospitals 
Of the  11 billing  errors,  90.9 percent 
Percent 
over-reimbursed  to the  hospitals.  This 
I  I  I  Emr  direction 
was not  a significant  improvement  upon  o 
Under-reimbursed 
the  100.0 percent  over-reimbursement  Over-reimbursed 
reported  in 1985. 
-50 
Hospitals  still over-reimbursed 
100 
19ss 
The  123 sample  discharges  originally 
carried  Relative  Weights  of 2.0777, 
Figure  4: Direction  of DRG  79 errors,  1985 
equivalent  to $6,478 in metropolitan 
&  1988 
hospitals  and  $5,479 in nonmetropolitan 
hospitals.  The  AMRA  reabstraction,  which  resulted  in  11 discharges  reassigned  to a 
DRG  other  than  DRG  79, reduced  the  case-mix  index  (CMI)  to 2.0057, a statistically 
a. Because  of the  smaller  sample  size that  results  from  DRG-specific  analysis,  estimates 
of coding for specific DRGs  are less precise  than  OIGS national  estimate.  Statistical  tests 
determined  whether  apparent  differences  were  real  (statistically  significant)  or could  be 
attributed  to random  error. 
4  significant  decline  of 0.0720.  This 
reduction  persisted  across  all hospital  $ gikm 
and  demographic  characteristics.  The 
net  CMI  change  in 1988 differed 
significantly  from  the  net  CMI  change 
20-
for DRG  79 bills in 1985.  It also 
differed  significantly  from  the  net  CMI 
change  for  all bills in 1988.  [Appendix 
lo-
E]. 
Extrapolation  of the  1988 CMI  change 
0-
to all  102,561 DRG  79 discharges  1985  1988 
projected  that  billing  errors  over-
reimbursed  hospitals  a statistically 
Figure  5: DRG  79 over-reimbursement  from 
significant  $22.7 million.  This  over-
miscoding,  1988 &  1985 
reimbursement  did not  statistically  differ 
from  the  $28.4 million  the  OIG  previously  reported  for  1985.  The  proportion  of 
errors  decreased  over  time,  but  the  increase  in DRG  79s frequency  completely  offset 
the  improvement  in billing accuracy. 
Reasons  for  errors 
AMRA  identified  only two types  of errors  in the  sample,  misspecification  and 
resequencing.  No miscoding  or other  errors  occurred.  [Appendix  F]. 
MissPecification	 The  attending  physician  wrote  down  the  wrong  narrative  diagnosis 
on the  attestation. 
Resequencing	 The  attending  physician  wrote  the  correct,  narrative,  principal 
diagnosis  on the  attestation,  but  the  hospital  substituted  a 
secondary  diagnosis  for the  principal  diagnosis. 
Misspecification  caused  81.8 percent  of the  11 billing  errors.  This  proportion 
significantly  exceeded  the  54.9 percent  misspecificat~on  errors  in  1985.- It also 
significantly  exceeded  the  63.2 percent  misspecifications  for all DRGs  in 1988. 
Resequencing  caused  18.2 percent  of the  samples  billing  errors.  This  proportion  did 
not  significantly  diffel  from  the  20.0 percent  resequencing  errors  in  1985. 
5
 ENDNOTES

1. Meyers  M,  Kleiman  M,  Stone  D, Lee  F,  Schutte  J, Hsia  D,  & Krushat  M.  DRG  79: 
respiratory  infection.  Washington,  DC: HHS  Office of Inspector  General,  1989.  Publication 
no. OAI-12-88-01190. 
2. Knight J W & Hsia D C, eds.  National  DRG  Validation  Study Update:  Technical  Report. 
Washington,  DC: HHS  Office of Inspector  General,  1992. Publication  no. OEI-12-90-00191. 
3. Knight J W & Hsia D C, eds.  National  DRG  Validation  Study Update:  Summary  Report. 
Washington,  DC: HHS Office of Inspector  General,  1992. Publication  no. OEI-12-90-00190. 
6
 . 
Health  Care 
DEPARTMENTOFHEALTHa  HUMANSERVICES  Financing  Admmwtratlon 
Memorandum 
ax  519W 
%iiii29@ 
Date 
 
9 
From  Acting Administrator 
Office of Inspector  General  (OIG)  Draft Report:  DRG 79 Validation  Study

Subject 
Update:  Respiratory  Infections  and Inflammations,  0EI-12-89-O0193

To  Byan  B. Mitchell

Principal Deputy  Inspector  General

We have  reviewed  the  subject  draft report  which examined the coding accuracy 
of prospective payment  discharges billed as diagnosis related  group (DRG)  79.  In a 
previous study, OIG  sampled  DRG  79 bills on a blinded basis and found upcoding 
that resulted  in overpayment  to hospitals of $28.4 million in 1985. 
In this repor~  OIG  documented  a significant improvement  in coding accuracy 
for DRG 79, from over 81 percent  in 1985 to over 91 percent  in 1988.  Despite  this 
improvement  the financial  impact of DRG  79 billing errors was not reduced 
significantly because  the errors  continue  to result in systematic overpayment to 
hospitals.  In addition,  hospitals  billed a larger number  of discharges to DRG  79 in 
1988. 
This report  contained  no recommendations  for firther  action, though OIG 
noted the findings of this report  support the recommendation  of an earlier  and 
broader  study:  National DRG  Validation  Study Update:  Summary Report, 
0EI-12-89-O0190.  In this earlier  repo~  OIG  recommended  that peer review 
organizations (PROS) continue  their surveillance  of hospital  coding  for DRG 
accuracy. 
We  disagree with tie  characteriution  of certain billing mistakes as coding 
errors in situations  where medical record coders are dependent  on physician 
narratives.  However, we agree with the broad recommendation  about  PROS 
surveillance of hospital bills for accuracy. 
Attached  for your consideration  are our detailed  comments. Thank you for the 
opportunity to review and comment  on this draft report.  Please advise us whether 
you agree with our comments  on the report  at your earliest  convenience. 
Attachment 
7 
s u.S. QOVSRNMENT  PRINTING  OFFICE: 1ss2 -522-060/5182  Comments of the Health  Care Financing Administration  (HCFA) 
on Office of the  Ins~ector General  (OIG)  Draft Report: 
DRG 79 Validation  StudVU~date:Res~iratorv  Infections and 
Inflammations.  OEI-12-89-00193 
General  Comment 
The findings set forth in this report  indicate  that 81.8 percent  (9 out of 11 cases) of 
DRG  79 billing errors uncovered  by the audit were caused by the failure  of the 
attending physician to indicate the principal  diagnosis correctly in the narrative  on the 
attestation.  We would not characterize  these as coding errors because medical record 
coders  use  a physicians  attested-to  narrative  when coding a Medicare  discharge.  Rather, 
this study  points  to problems  with  the  physician  narratives. 
Therefore,  we agree with the broad  recommendation  that peer  review organizations 
continue  their sumeillance  of hospital  bills for accuracy including both physician 
descriptions of diagnoses and procedures,  and the subsequent  coding of narratives  by 
medical record personnel. 
Technical Comments 
Page 1.  ICD-9-CM should be written  out as follows: International  Classification of 
Diseases, Ninth Revision, Clinical Modification. 
Page 2.  In October  1991, The American  Medical Record Association (AMRA)  formally 
changed its name to the American  Health  Information  Management  Association 
(AHIMA).  Even though this audit was conducted  under the auspices of AMRA,  OIG 
may wish to make  mention  of this  change  in the  introduction  of this report.  Suggested 
language  is as follows: 
OIG contracted with the American  Medical Records Association (AMRA)  to 
reabstract  the charts.  That  association  has since changed its name to the 
American Health  Information  Management  Association (AHIMA),  but will 
be referred  to herein  as AMRA. 
. . 
8  APPENDIX  A 
Project  participants 
OIG 
Cathaleen  A. Ahern,  B.A. 
Evan  J. Buckingham,  B.A. 
David  C. Hsia,  J.D.,  M.D.,  M.P.H. 
Thomas  F. Komaniecki,  M.P.A. 
W. Mark  Krushat,  M.P.H. 
Linda  M. Moscoe,  B.A. 
Brian  P. Ritchie,  B.A. 
Barry  L. Steeleyb 
John  M. Traczyk,  B.A. 
HCFA 
Timothy  F. Greene,  M.A.,  M.B.A. 
Stephen  F. Jencks,  M.D. 
Michael  R. McMullan,  M.B.A. 
Harry  L. Savitt,  Ph.D. 
Jeanette  M. Smith,  M.D.,  M.P.H.c 
Malcolm  A. Sneen,  B.S. 
RAND  Corporation 
Haya  P. Rubin,  M.D.,  Ph.Dd 
Baxter-Health  Data  Institutee 
Patricia  J. Baxter,  R.N. 
Patricia  Cassidy-Tsnosas,  R.N. 
Annette  M. Delaney,  R.N.,  M.A. 
Ellen  B. Inghilleri,  R.N. 
Janet  Mathews,  A.R.T. 
Laurie  H. Moore,  R.R.A. 
Claire  Shannon,  A.R.T. 
Michele  A. Wiese,  B.A. 
AMRA 
Margret  K. Amatayakul,  M.B.A.,  R.R.A. 
Mary  Converse,  R.R.A. 
b. Now at Health  Audit  Services,  Ellicott  City, MD. 
c. Now at  the Journal  of the  American  Medical  Association,  Chicago,  IL. 
d. Now at Johns  Hopkins  Medical  Institutions. 
e. Ceased  operations  February  16, 1990. 
A -1  Nicholas  J. Cotsonas,  M.D.f

Linda  Ertl,  R.R.A.

Rita  M. Finnegan,  R.R.A.

Desla  Mantilla,  A.R.T.

Barbara  Manny,  R.R.A.

Sonia  Martyniuk,  R.R.A.

Toula  Nicholas,  A.R.T.

Charlotte  Razor,  R.R.A.

LouAnn  Schraffenberger,  R.R.A.

Lynn Smetko,  R.R.A.

Dawn  Smith,  A.R.T.

Joan  Zacharias,  A.R.T.

BOTEC  Analvsis  Corporation

Geraldine  M. Berenholz,  R.R.A.

Andrew  H. Chalsma,  B.A.

David  P. Cavanagh,  M.A.,  Ph.D.

Janet  W. Knight,  R.N.,  Ph.D.

Amy L. Lockwood,  B.A.

Contract  information 
Contractor

BOTEC  Analysis  Corporation

1698 Massachusetts  Avenue

Cambridge,  MA  02138

Proiect  Officer

David  Hsia,  J.D.,  M.D.,  M.P.H.

Office  of Inspector  General

330 Independence  Avenue

Washington,  D.C.  20201

Contract

HHS-1OO-9O-OO23

Firm-fixed  price  contract

$203,257

f. Outside  contractor. 
A -2  APPENDIX  B 
ICD-9-CM  codes  in DRG  79 
003.22  Salmonella  pneumonia 
006.4  Amebic  lung abscess 
010.0  Primary  tuberculosis  complex 
010.1  Primary  tuberculosis  pleurisy 
010.8  Primary  progressive  tuberculosis  not  elsewhere  classifiable 
010.9  Prima~  tuberculosis  not  otherwise  specified 
011.0  Tuberculosis  lung infiltrative 
011.1  Tuberculosis  lung nodular 
011.2  Tuberculosis  lung with  cavity 
011.3  Tuberculosis  of bronchus 
011.4  Tuberculosis  lung fibrosis 
011.5  Tuberculosis  bronchiectasis 
011.6  Tuberculosis  pneumonia 
011.7  Tuberculosis  meumothorax 
011.8  Pulmonary  tu~erculosis  not  elsewhere  classifiable 
011.9  Pulmonary  tuberculosis  not  otherwise  specified 
012.0  Tuberculosis  pleurisy 
012.1  Tuberculosis  thoracic  nodes 
012.2  Isolated  tracheal  tuberculosis 
012.8  Respiratory  tuberculosis  not  elsewhere  classifiable 
020.3  Primary  pneumonic  plague 
020.4  Secondary  pneumonic  plague 
020.5  Pneumonic  plague  not  otherwise  specified 
021.2  Pulmonary  tularemia 
022.1  Pulmonary  anthrax 
031.0  Pulmonary  mycobacteria 
039.1  Pulmona~  actinomycosis 
052.1  Varicella  pneumonitis 
055.1  Postmeasles  pneumonia 
073.0  Ornithosis  pneumonia 
095.1  Syphilis of lung 
112.4  Candidiasis  of lung 
114.0  Primary  coccidioidomycosis 
115.05  Histoplasma  capsulatum  pneumonia 
115.15  Histoplasma  duboisii  pneumonia 
115.95  Histoplasmosis  pneumonia 
121.2  Paragonimiasis 
122.1  Echinococcus  granulosus  of the  lung 
130.4  Toxoplasma  pneumonitis 
136.3  Pneumocystosis 
482.0  K. Pneumonia  pneumonia 
B-1  482.1  Pseudomonas  pneumonia 
482.4  Staphylococcus  pneumonia 
484.1  Pneumonia  with  Cytomegalif  inclusion  disease 
484.3  Pneumonia  in whoop  cough 
484.5  Pneumonia  in anthrax 
484.6  Pneumonia  in aspergillosis 
484.7  Pneumonia  in other  systemic  mycoses 
484.8  Pneumonia  in infectious  disease  not  elsewhere  classifiable 
507.0  Food/vomit  pneumonitis 
507.1  Oil/essence  pneumonitis 
507.8  Solid/liquid  pneumonitis  not  elsewhere  classifiable 
510.9  Empyema  without  fistula 
511.1  Bacterial  pleurisy  with  effusion  not  tuberculosis 
513.0  Abscess  of lung 
513.1  Abscess  of mediastinum 
519.2  Mediastinitis 
510.0  Empyema  with fistula 
795.5  Tuberculin  test  reaction 
v71.2  Observation  for suspected  tuberculosis 
B-2  APPENDIX 
C

Sample  representativeness 
Number  [percent]  Population  Sample  Chi-square 
Hospital  demogra~hv 
1-99 beds  22,539 [22.0]  37 [30.1]  5.04, 2 df, P= O.081 
100-299 beds  39,061 [38.1]  48 [39.0] 
300+  beds  40,918 [39.9]  38 [30.9] 
Metropolitan  72,185 [70.4]  88 [71.5]  0.06, 1 df, P= O.195 
Nonmetropolitan  30,333 [29.6]  35 [28.5] 
Teaching  37,168 [36.3]  43 [35.0]  0.07, 1 df, P= O.21O 
Nonteaching  65,350 [63.7]  80 [65.0] 
Profit  13,910 [13.9]  16 [13.0]  0.06, 1 df, P= O.199 
Nonprofit  86,303  [86.1]  107 [87.0] 
Patient  demo~ra~hv 
<65  years  8,232 [8.0]  6 [4.9]  3.32, 3 df, P= O.652 
65-74 years  25,384  [24.8]  29 [23.6] 
75-84 years  38,686 [37.7]  56 [45.5] 
85+  years  30,259 [29.5]  32 [26.0] 
Male  54,795 [53.4]  62 [50.4]  0.37, 1 df, P= O.451 
Female  47,766 [46.6]  61 [49.6] 
White  89,424  [87.2]  110 [89.4]  1.38, 3 df, P=0.289 
Black  8,579 [8.4]  10 [8.1] 
Other  1,808 [1.8]  2 [1.6] 
Unknown  2,750 [2.7]  1 [0.8] 
Total  102,561 [100.0]  123 [100.0] 
Note:  Population  frequencies  may not  sum to total  because  of missing  cases. 
c-l
 APPENDIX  D 
DRG  79 billing  erro~  1985 and  1988 
Number  [proportion  1988  1985  t-test 
~ standard  error] 
Hos~ital  demo~ra~hy 
1-99 beds  1 [2.7 ~ 2.7]  24 [33.3 ~ 9.8]  6.37 
100-299 beds  6 [12.5 ~ 4.8]  25 [20.0 ~ 8.2]  1.41 
300+  beds  4 [10.5 t  5.0]  25 [8.0 & 5.5]  0.58 
Metropolitan  10 [11.4 t  3.4]  46 [28.5 f  6.9]  3.09 
Nonmetropolitan  1 [2.9 f  2.9]  28 [12.2 ~ 6.6]  2.39 
Teaching  5 [11.6 f  4.9]  22 [9.3 * 4.7]  0.53 
Nonteaching  6 [7.5 ~ 3.0]  52 [18.3 ~ 5.7]  2.22 
Profit  1 [6.3 ~ 6.3]  7 [13.8 t  8.0]  2.14 
Nonprofit  10 [9.3 t  2.8]  67 [18.8 ~ 4.8]  1.93 
Patient  demo~ra~hv 
<65  years  2 [33.3 * 21.1]  7 [0.0 t  0.0]  6.51 
65-74 years  4 [13.8 A 6.5]  19 [26.2 f  11.7]  2.01 
75-84 years  3 [5.4 * 3.0]  26 [50.8 ~ 15.6]  6.39 
85+  years  2 [6.3 ~ 4.3]  22 [12.9 t  6.4]  1.68 
Male  2 [3.2 ~ 3.2]  40 [13.3 * 4.1]  3.23 
Female  9 [14.8 ?  4.6~  34 [22.3 ~ 9.3]  1.19 
White  10 [9.1 t  2.8] 
Black  o [0.0 t  O.O] 
Other  1 [50.0 t  50.0] 
Unknown  o [0.0 t  0.0] 
Total  11 [8.9 *2.6]  74 [18.4 ~ 4.4]  L97 
D-1  APPENDIX  E

DRG  79 case-mix  index  change,  1985 and  1988 
Relative  weight  f  1988  1985  Difference  t-test 
standard  error 
Hos~ital  demo~raphy 
1-99 beds  -0.0213 ~ 0.0213  -0.2960 f  0.0909  0.2747  6.31 
100-299 beds  -0.1149 t  0.0450  -0.2086 ~ 0.0863  0.0937  1.79 
300+  beds  -0.0672 f  0.0456  -0.0861 t  0.0606  0.0189  0.44 
Metropolitan  -0.0917 t  0.0314  -0.2623 t  0.0669  0.1706  3.25 
Nonmetropolitan  -0.0226 f  0.0226  -0.1278 f  0.0751  0.1052  2.53 
Teaching  -0.1075 ~ 0.0465  -0.0865 t  0.0435  -0.0210  0.52 
Nonteaching  -0.0529 ~ 0.0260  -0.1916 f  0.0654  0.1387  2.72 
Profit  -0.0557 f  0.0557  -0.1401 ~ 0.0817  0.0844  2.60 
Nonprofit  -0.0745 k 0.0257  -0.1834 ~ 0.0488  0.1089  2.29 
Patient  demo~raphv 
<65  years  -0.3657 & 0.2313  0.0000 k  0.0000  -0.3657  6.51 
65-74 years  -0.1182 f  0.0564  -0.2980 t  0.1379  0.1798  2.75 
75-84 years  -0.0230 ~ 0.0223  -0.4640 ~ 0.1486  0.4410  6.73 
85+  years  -0.0608 * 0.0430  -0.1105 t  0.0568  0.0497  1.34 
Male  -0.0271 ~ 0.0190  -0.1288 f  0.0407  0.1017  3.48 
Female  -0.1177 t  0.0426  -0.2245 ~ 0.0988  0.1068  1.67 
Total  -0.0720 f  0.0235  -0.1809 ~ 0.0457  0.1089  2.34 
E-1
 APPENDIX  F 
Reasons  for DRG  79 erro~  1985 and  1988 
Number 
[percent]  Total  1988  Total  1985 
Misspecification  9  [81.8]  6  [54.9] 
Miscoding  o  [0.0]  2  [13.3] 
Resequencing  2  [18.2]  3  [20.0] 
Other  o  [0.0]  4  [26.7] 
Total  11  [100.0]  15  [100.0] 
F -1