NCHS Data Brief ■ No. 32 ■ March 2010

u.s. department of health and human services

Centers for Disease Control and Prevention

National Center for Health Statistics

Health Care Utilization Among Adults Aged 55–64 Years:

How Has It Changed Over the Past 10 Years?

Virginia M. Freid, M.S., and Amy B. Bernstein, Sc.D.

Key findings

• The percentage of physician 

office and hospital outpatient 

department (OPD) visits during 

which an MRI/CT/PET scan 

was ordered doubled, to 4%, 

and the percentage of hospital 

emergency department visits 

with an MRI/CT scan more 

than tripled, to 16%.

• The percentage of physician 

office and OPD visits with at 

least five drugs prescribed more 

than doubled, to 25%.

• Inpatient hospitalization 

rates were similar in 2006 

and 1996, but the types of 

procedures and surgeries 

performed have changed. 

Hospitalization rates for 

coronary artery stent insertions, 

hip replacements, and knee 

replacements rose sharply, 

while rates for some other 

procedures declined. 

• Ambulatory surgery visit 

rates were almost twice as 

high in 2006 as in 1994–1996, 

and for some types of 

ambulatory procedures, such as 

colonoscopies, the increase was 

even greater.

Between ages 55 and 64, chronic illnesses become more common and the use 

of ambulatory and inpatient health care increases, compared with younger 

ages (1). This segment of the population is projected to grow rapidly during 

the next 10 years, driven by the aging of the baby boom generation (2). 

The current group of persons aged 55–64 years differs in health status and 

prevalence of disease risk factors from past cohorts of adults aged 55–64. 

Adults aged 55–64 in 2006 were more likely to be obese and hypertensive 

than their counterparts about a decade earlier (1), but both cohorts were 

equally likely to exercise regularly, and the 2006 cohort was slightly less 

likely to smoke cigarettes (3). Because of continuing advances in medicine, 

the 2006 cohort has had more opportunity to utilize drugs, tests, imaging, 

procedures, and surgeries than its 1996 counterpart. This brief examines how 

health care utilization has changed for persons aged 55–64—a group that is 

about to enter the Medicare program and that has been a recent focus of the 

health care policy debate. Examining the utilization patterns for this large and 

growing group may provide insight into policy debates and into future health 

care utilization by Medicare beneficiaries. 

Keywords: medical technology • ambulatory • inpatient

Between 1996 and 2006, for persons aged 55–64 years, 

ambulatory visit rates of all types increased. 

0 50 100 250 300 350 400 450 500

Inpatient hospital

discharges

Ambulatory

surgery visits1

ED visits1

Physician office/

OPD visits1

1

Statistically significant difference (p < 0.05) between 1996 (or 1994–1996) and 2006.

NOTES: OPD is outpatient department; ED is emergency department. Ambulatory surgery visits were for 1994–1996.

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, National Hospital Ambulatory Medical Care Survey, National 

Survey of Ambulatory Surgery, and National Hospital Discharge Survey.

Figure 1. Ambulatory care visits, ambulatory surgery visits, and inpatient hospital discharges 

among adults aged 55–64 years: United States, 1996 and 2006

1996

2006

Number per 100 population

385.0

433.3

26.3

31.2

12.2

20.3

15.2

14.2
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■  2  ■

• Physician office and hospital outpatient department (OPD) visit rates were 13% higher in 

2006 than in 1996 (Figure 1).

• Hospital emergency department (ED) visit rates were 19% higher in 2006 than in 1996.

• Ambulatory surgery visit rates were 66% higher in 2006 than in 1994–1996. 

• Inpatient hospitalization rates were similar in 2006 and 1996.

Over the same period, use of ultrasound or MRI/CT/PET scans by those 

aged 55–64 years increased substantially in ambulatory settings.

0 10 20 30 40 50 60 70 80 90 100

MRI/CT1

Ultrasound1

X-ray

Any blood test1

MRI/CT/PET1

Ultrasound1

X-ray1

Any blood test

1

Statistically significant difference (p < 0.05) between 1996 and 2006.

NOTE: OPD is outpatient department; ED is emergency department; MRI is magnetic resonance imaging; CT is computed tomography; PET is positron emission 

tomography.

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey.

Figure 2. Ambulatory care visits with selected tests or imaging ordered or provided among adults aged 55–64 years: 

United States, 1996 and 2006

1996

2006

Percent of visits

Physician office/OPD visits

ED visits

20.4

22.2

10.1

7.0

1.4

2.7

1.8

3.9

39.9

57.4

44.8

46.4

1.2

3.0

4.4

15.8

• The percentage of physician office and OPD visits with an ultrasound or a magnetic 

resonance imaging (MRI)/computed tomography (CT)/positron emission tomography 

(PET) scan ordered or provided during the visit was higher in 2006 than in 1996, while 

the percentage of these visits with an x-ray ordered or provided during the visit was lower 

(Figure 2).

• A greater percentage of ED visits had a blood test, ultrasound, or MRI/CT scan ordered or 

provided during visits in 2006 than in 1996. 
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The percentage of physician office and OPD visits for 55–64 year-olds in 

which drugs were prescribed also grew, with major increases in the share 

of visits with multiple drugs prescribed. 

0 10 20 30 40 50 60 70 80 90 100

At least five drugs

At least three drugs

At least one drug

At least five drugs1

At least three drugs1

At least one drug1

1

Statistically significant difference (p < 0.05) between 1996 and 2006.

NOTES: OPD is outpatient department; ED is emergency department. Drugs are prescription or over-the-counter. 

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey.

Figure 3. Ambulatory care visits with drugs ordered, provided, or continued among adults aged 55–64 years:

United States, 1996 and 2006

Percent of visits

Physician office/OPD visits

ED visits

65.0

76.4

23.1

43.1

8.9

24.8

77.1

78.8

29.0

31.3

9.6

8.5

1996

2006

• The percentage of physician office and OPD visits with at least one drug ordered, provided, 

or continued during the visit was 18% higher in 2006 than in 1996. The percentage with 

at least three drugs recorded during the visit was nearly twice as high in 2006; and the 

percentage with at least five drugs recorded was nearly three times as high (Figure 3).

• In contrast, the percentage of visits to EDs with at least one, at least three, or at least five 

drugs ordered, provided, or continued during the visit was similar in 2006 and 1996.

The share of adults aged 55–64 years who used multiple prescription drugs 

in the month before interview was much higher in 2003–2006 than in 

1988–1994. 

0 10 20 30 40 50 60 70 80 90 100

At least five

prescription drugs1

At least three

prescription drugs1

At least one

prescription drug1

1

Statistically significant difference (p < 0.05) between 1988–1994 and 2003–2006.

SOURCE: CDC/NCHS, National Health and Nutrition Examination Survey.

Figure 4. Prescription drug use in the month before interview among adults aged 55–64 years: United States,

1988–1994 and 2003–2006

Percent of persons

61.7

72.1

25.3

46.4

9.6

24.9

1988–1994

2003–2006
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• The percentage of adults with any prescription drug use in the month before interview was 

17% higher in 2003–2006 than in 1988–1994. The percentage with at least three prescription 

drugs was nearly twice as high, and the percentage with at least five prescription drugs was 

more than twice as high (Figure 4).

Between 1996 and 2006, rates for some types of inpatient procedures 

increased for 55–64 year-olds, while others remained steady or declined.

0 10 20 30 40 50 60 70 80 90 100

Upper endoscopy

(EGD)

Colonoscopy

Gallbladder

removal

Coronary artery

bypass graft

Total hip

replacement

Total knee

replacement

Coronary artery

stent insertion

1

Statistically significant difference (p < 0.05) between 1996 and 2006.

NOTES: Selected procedures were any-listed. EGD is esophagogastroduodenoscopy. 

SOURCE: CDC/NCHS, National Hospital Discharge Survey.

Figure 5. Inpatient hospital discharges with selected procedures performed among adults aged 55–64 years:

United States, 1996 and 2006

Number per 10,000 population

Rates were significantly higher in 2006 than in 19961

Rates were significantly lower in 2006 than in 19961

Rates were similar in 2006 and in 1996

23.4

54.6

19.6

45.2

9.2

17.7

44.8

22.5

31.9

19.7

25.2

24.5

52.1

51.3

1996

2006

• Inpatient hospitalization rates were about twice as high for coronary artery stent insertions, 

total knee replacements, and total hip replacements in 2006 as in 1996 (Figure 5). 

• Inpatient hospitalization rates were lower for coronary artery bypass surgery and gallbladder 

removal in 2006 than in 1996. 

• Inpatient hospitalization rates were similar in 2006 and 1996 for colonoscopies and upper 

endoscopies.
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The growth of ambulatory surgery between 1994–1996 and 2006 for 55–64 

year-olds was particularly pronounced for certain procedures.

0 100 200 300 400 500

Insertion of

eye lens

Gallbladder

removal 

Arthroscopy of

knee

Upper endoscopy

(EGD)

Colonoscopy

1

Statistically significant difference (p < 0.05) between 1994–1996 and 2006.

NOTE: EGD is esophagogastroduodenoscopy. 

SOURCE: CDC/NCHS, National Survey of Ambulatory Surgery.

Figure 6. Ambulatory surgery visits among adults aged 55–64 years: United States, 1994–1996 and 2006

Number per 10,000 population

Rates were significantly higher in 2006 than in 1994–19961

Rates were similar in 2006 and in 1994–1996

142.3

109.8

223.3

37.8

64.8

85.3

119.9

15.2

29.0

460.4

1994–1996

2006

• Ambulatory surgery visit rates for colonoscopies tripled between 1994–1996 and 2006 

(Figure 6). 

• Ambulatory surgery visit rates for upper endoscopies and gallbladder removals doubled 

between 1994–1996 and 2006.

• Knee arthroscopy rates performed in ambulatory surgery centers increased 71% during this 

time period.

Summary

Over a relatively short period, from 1996 through 2006, utilization of ambulatory services among 

adults aged 55–64 years increased significantly. During this period, physician office and OPD 

visits became more “medication intensive,” with a greater percentage of these visits involving the 

prescription and management of drugs—in many cases multiple drugs. Utilization of advanced 

imaging technologies also increased for this age group. The percentage of physician office and 

OPD visits during which an MRI/CT/PET scan or ultrasound was ordered or provided grew, 

while the percentage of these visits ordering or providing x-rays declined. ED visits were more 

than three times as likely to include advanced imaging scans such as MRI/CT in 2006.

The overall hospital discharge rate was unchanged during the period examined, although the 

hospital days of care rate declined, reflecting shorter average lengths of stay (1). The types of 

inpatient procedures performed also differed. Some inpatient procedure rates declined because 

newer procedures were being substituted for older ones (e.g., coronary artery stent insertions 

replacing coronary artery bypass surgery) (4). Other types of inpatient procedure rates declined 

because the procedures shifted from inpatient to outpatient settings (e.g., gallbladder removal) 

(5). In contrast, several types of inpatient procedures demonstrated substantial growth over the 
NCHS Data Brief ■ No. 32 ■ March 2010

■  6  ■

10-year period because of technological improvements that made the procedures easier 

to perform, with shorter recovery periods and more successful outcomes (e.g., total knee 

replacements and total hip replacements) (6,7). 

Trends in health care utilization among those aged 55–64 years reflect a general trend in the 

increasing use of ambulatory care, newer technologies, imaging, procedures, and drugs (1). A 

similar shift to greater use of ambulatory care has been reported for care for chronic conditions 

(8). In one decade, the shift of the locus of care from inpatient to ambulatory settings has been 

dramatic. These findings demonstrate the rapid evolution of the health care system, which has 

affected the care received by persons aged 55–64, as well as those in other age groups.

Definition

Procedures: Defined based on the following International Classification of Diseases, Ninth 

Revision, Clinical Modification (ICD–9–CM) codes: 

• Coronary artery stent insertion: 36.06, 36.07

• Total knee replacement: 81.54

• Total hip replacement: 81.51

• CT/MRI scans: 87.03, 87.41, 87.71, 88.01, 88.38, 88.91–88.97

• Coronary artery bypass graft: 36.1

• Gallbladder removal: 51.2

• Colonoscopy: 45.23, 45.25

• Upper endoscopy or esophagogastroduodenoscopy (EGD): 45.13, 45.16

• Knee arthroscopy: 80.26

• Insertion of eye lens: 13.7

Data sources and methods

Estimates in this brief are based on data from five national surveys conducted by the National 

Center for Health Statistics: 

• National Hospital Discharge Survey (NHDS) data were used to estimate inpatient 

hospitalizations. NHDS collects information from a national sample of inpatient stays in 

nonfederal, short-stay hospitals in the United States. Patient information is collected from medical 

records and automated data files and includes demographics, length of stay, diagnoses, and up to 

four procedures. Any-listed procedure rates count a specific procedure only once, regardless of 

the number of times it was performed. For more information, visit the NHDS website at:

http://www.cdc.gov/nchs/nhds.htm.

• National Ambulatory Medical Care Survey (NAMCS) data were used to estimate physician 

office visits. NAMCS collects information from a national sample of visits to office-based 

physicians in the United States. Patient information is collected from medical records and 

includes diagnoses; number of drugs (over-the-counter and prescription) ordered, provided, or 

continued during the visit; and selected procedures and tests ordered or performed during the 

visit. Data on scans ordered or performed during the office visit were collected using checkboxes 

and a write-in procedure field. In 1996, there were separate checkboxes for MRI and CT scans; 

in 2006, there was a combined checkbox for MRI, CT, and PET scans. Some of the increase in 
NCHS Data Brief ■ No. 32 ■ March 2010

■  7  ■

advanced imaging scans noted during the period examined is due to improved questionnaire 

design and editing procedures that better captured PET scans. Data for physician office visits 

were combined with data from OPDs to provide a summary measure of ambulatory care 

utilization. For more information, visit the Ambulatory Health Care Data website at:

http://www.cdc.gov/nchs/ahcd.htm.

• National Hospital Ambulatory Medical Care Survey (NHAMCS) data were used to 

estimate OPD and ED visits. NHAMCS collects information from a national sample of visits to 

OPDs and EDs. Patient information is collected from medical records and includes diagnoses; 

number of drugs (over-the-counter and prescription) ordered, provided, or continued during the 

visit; and selected procedures and tests ordered or performed during the visit. In OPD settings, 

data on scans ordered or performed during the visit were collected using checkboxes and a 

write-in procedure field. In 1996, there were separate checkboxes for MRI and CT scans; in 2006, 

there was a combined checkbox for MRI, CT, and PET scans. Some of the increase in advanced 

imaging scans noted during the period examined is due to improved questionnaire design and 

editing procedures that better captured PET scans. In ED settings, data were collected on MRI 

and CT scans by using a checkbox. For more information, visit the Ambulatory Health Care Data 

website at: http://www.cdc.gov/nchs/ahcd.htm.

• National Survey of Ambulatory Surgery (NSAS) data were used to estimate ambulatory 

surgery visit rates. NSAS is a national survey of ambulatory surgical care in hospital-based and 

freestanding ambulatory surgery centers. NSAS was conducted from 1994 to 1996 and again in 

2006. The 2006 survey included pain block locations, whereas the earlier surveys did not. Patient 

information is collected from medical records and includes diagnoses and up to six procedures 

performed during the visit. The small number of persons who had an ambulatory surgery visit 

and were subsequently admitted to an inpatient facility were omitted from NSAS estimates to 

avoid potential double counting. For more information, visit the National Survey of Ambulatory

Surgery website at: http://www.cdc.gov/nchs/nsas.htm.

• National Health and Nutrition Examination Survey (NHANES) data were used to estimate 

the percentage of the population with prescription drug use in the past month. NHANES provides 

estimates of the health status of the civilian noninstitutionalized population of the United States. 

The survey includes clinical examinations, selected medical and laboratory tests, and selfreported data. For more information, visit the NHANES website at: http://www.cdc.gov/nchs/

nhanes.htm.

Civilian population estimates from the U.S. Census Bureau were used to calculate inpatient 

hospitalization and ambulatory surgery visit rates. Civilian noninstitutionalized population 

estimates were used to calculate physician office, OPD, and ED visit rates.

Differences between subgroups were evaluated using the univariate t-statistic. All significance 

tests were two-sided, using p < 0.05 as the level of significance. All comparisons reported in the 

text are statistically significant unless otherwise indicated. Data analyses were performed using 

SAS version 9.1 (SAS Institute, Cary, N.C.) and SUDAAN version 9.0 (RTI, Research Triangle 

Park, N.C.). 

About the authors

Virginia Freid and Amy Bernstein are with the Centers for Disease Control and Prevention’s 

National Center for Health Statistics, Office of Analysis and Epidemiology. 
NCHS Data Brief ■ No. 32 ■ March 2010

References

1. National Center for Health Statistics. Health, United States, 2009: With 

special feature on medical technology. Hyattsville, MD. 2010. Available 

from: http://www.cdc.gov/nchs/hus.htm.

2. U.S. interim projections by age, sex, race, and Hispanic origin: 2000–

2050 [online]. U.S. Census Bureau Population Projections. Available from: 

http://www.census.gov/population/www/projections/usinterimproj/.

3. CDC/NCHS, National Health Interview Survey, unpublished analysis.

4. Baim DS. Percutaneous coronary intervention. In: Fauci AS, Brauwald 

E, Kasper DL, et al., eds. Harrison’s Principles of Internal Medicine, 17th ed, 

ch 240. New York, NY: McGraw-Hill; 1544–8. 2008.

5. Ellison EC, Carey LC. Lessons learned from the evolution of the 

laparoscopic revolution. Surg Clin North Am 88(5):927–41. 2008.

6. Learmonth ID, Young C, Rorabeck C. The operation of the century: Total 

hip replacement. Lancet 370(9597):1508–19. 2007.

7. Branson JJ, Goldstein WM. Primary total hip arthroplasty. AORN J 

78(6):947–74. 2003.

8. Decker SL, Schappert SM, Sisk JE. Use of medical care for chronic 

conditions. Health Aff (Millwood) 28(1):26–35. 2009.

Suggested citation

Freid VM, Bernstein AB. Health care 

utilization among adults aged 55–64 years: 

How has it changed over the past 10 years? 

NCHS data brief, no 32. Hyattsville, MD: 

National Center for Health Statistics. 2010.

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Health & Human Services

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