National Center for Health Statistics

Statistics on the time interval since last physician visit and the number and percent of persons under 17’years of age with routine physical examinations in past year, by sex~ agel residence8 geographic region, color, fami Iy income, education of the head of the fami Iy, usual activity statusl and mar­ ital status. Based on data CO I Iected in household interviews during the period July 1963-June 1964.


Library of Congress Cataloging in Publication Data
Ranofsky, Abraham L.
Utilization of short-stay hospitals. Statistics in this report provide national esti mates on the utilization of non-Federal shortstay hospitals during 1976. Data .are summarized for the demographic characteristics of the pa tients discharged, characteristics of the hospitals where patients were treated, conditions diag nosed, and surgical operations performed.
The data on discharges from short-stay hos pitals were collected by means of the Hospital Discharge Survey (HDS). This survey has been conducted by the National Center for Health Statistics continuously since the beginning of 1965.
Information for the Hospital Discharge Sur vey is abstracted from the face sheets of the medical records sampled for inpatients dis charged from a national sample of the non-Federal general and special short-stay hospitals. Data for newborn infants are excluded from this report. The sample for 1976 included approxi mately 223,000 medical records from 419 hospi tals that participated in the survey. The survey design, data collection procedures, presentation of the estimates, and reliability of the estimates are described in appendix I. A detailed report on the design of the Hospital Discharge Survey has been published. ' Measurements of hospital utibzation are shown in terms of frequencies, rates of dis charges and of days of care, percent distribu tions, and average lengths of stay. The estimates are presented by age, sex, and color of patients discharged and by geographic region, bed size, and ownership of the short-stay hospitals. Con ditions diagnosed and surgical operations performed are shown by patient and hospital char acteristics. Estimates of 1976 frequencies and rates for selected diagnostic and surgical cate gories are compared with the data for 1970 and 1975. Coding of medical data for patients hospi talized is done according to the Eighth Revision International Classification of Diseases, Adapted for Use in the United States2 (ICDA), with some modifications.
Conditions diagnosed and surgi cal operations performed are grouped by the classes of the ICDA. Within these classes a few diagnoses and operations or groups thereof are shown which were selected primarily because of large frequencies or because they are of special interest. Residual categories of the diagnostic and surgical classes are not shown in the tables. A maximum of five diagnoses and three opera tions is coded for ,each medical record in the sample according to the ICDA.
Familiarity with the definitions used in this report is important for interpreting the data and for making comparisons with statistical data on short-stay hospital utilization which are available from other sources. Definitions of the terms used are presented in appendix II.
Information on short-stay hospital utiliza tion is also collected by another program of the National Center for Health Statistics, the Health Interview Survey. Estimates from the Health Interview Survey are generally smaller for num ber of discharges and longer for. average length of stay than Hospital Discharge Survey estimates because of differences in collection procedures, population sampled, and definitions. Data from the Health Interview Survey are published by the National Center for Health Statistics in Series 10 of the Vital and Health Statistics reports.

UTILIZATION OF SHORT-STAY HOSPITALS BY CHARACTERISTICS OF INPATIENTS AND HOSPITALS
There were an estimated 34.4 million inpa tients, excluding newborn infants, discharged from non-Federal short-stay hospitals during 1976. These patients utilized approximately 260.3 million days of care and their average length of stay was 7.6 days. Patients hospital ized accounted for 163 discharges and 1,236 days of care per 1,000 persons in the civilian noninstitutionalized population.

Sex and Age
Patients discharged from short-stay hospitals during 1976 included 13.8 million males and 20.6 million females (table 1). The estimated rates per 1,000 population were 135 for males and 189 for females, or about 40 percent higher for femaIes than the rate for males. The number and rate of discharges are always higher for fe males than for males primarily because of the large number of women of age group 15-44 years, the childbearing years, hospitalized for deliveries and other obstetrical conditions. Ex cluding deliveries, the rate for females dis charged was 160, or only about 19 percent higher than the rate for males (table 7).
With a few exceptions, notably childrenunder age 1, annual rates of discharges increased consistently with each older age group for males and for females excluding deliveries. However, for females including deliveries the discharge rate for women of ages 15-44 years was higher (2 10 per 1,000 population) than for age group 45-64 years (200 per 1,000 population). Dis charge rates for the oldest age group by sex were about five times higher than for the youngest age group.
In 1976, male patients utilized an estimated 111 .l million days of care in short-stay hospitals compared with 149.2 million days of care uti lized by females (table 2). The number of days of care per 1,000 population was 1,093 for males compared with 1,369 for females, or about 25 percent higher for females than for males, Differences between the rates of days of care for males and females were smaller than for discharges mainly because the average length of stay for about 4 million women hospitalized for obstetrical conditions was only 3.8 days.
The annual number of days of care per 1,000 population increased with advancing age from 317 for patients under age 15 years to 4,164 for age group 65 years and over, or about 13 times (table 2). For the more detailed age groups the days of care rates varied from 230 for age group 5-14 years to 5,705 for age group 75 years and over, or almost 25 times higher. The much higher increase in the rate of days of care than of discharges from the youngest to the old est age group was due to long average lengths of stay for the aged. Average length of stay is longer for the aged because of the greater sever ity of illness. This is indicated by larger propor tions of older than younger patients with in capacitating chronic illnesses, and the highest proportion of any age group with multiple diag noses, both of which result in long average lengths of stay and also high annual rates of days of care.
Average length of stay for all patients in short-stay hospitals was 7.6 days in 1976. Males were hospitalized for an average of 8.1 days compared with 7.2 days for females (table 2). Females who were not hospitalized for deliveries had an average stay of 7.8 days, or only 0.3 day shorter than for males.
With a few exceptions, average length of stay increased with advancing age from 4.4 days for patients under age 15 years to 11.5 days for pa tients aged 65 and older (table 2). Differences by sex were largest during the childbearing years. Hospital days for age group 15-44 years averaged 6.5 days for males and 5.1 days for females.
Almost half (48 percent) of the patients in short-stay hospitals in 1976 were discharged within 4 days of admission (table 3). A smaller proportion of males (46 percent) than of fe males (50 percent) remained in hospitals for fewer than 5 days. The percentage of patients hospitalized fewer than 5 days decreased with each older age group from 73 percent for age group under 15 years to 26 percent for age group 65 years and over. Conversely, the proportion of patients hospitalized for 3 weeks or longer increased from 2 percent for under age 15 years to 13 percent for patients of ages 65 years and older. About 6 percent of all patients were hospitalized for 3 weeks or longer.

Color
Color of patients is presented in this report as "white" and "all other." In 1976, there were 26.2 million patients identified on the face sheets of the medical records as white and 3.8 million as of all other color groups (table 4). However, color was not reported for an addi tional 4.4 million patients, or a larger number than in the "all other" color group. As a result, rates were not computed by color and caution should be used in drawing conclusions from the data by color.
Some demographic characteristics differed between the two color groups. The largest dif ferences between white and all other patients were in the distributions of discharges by age. White patients as a group were older than all other patients. About 50 percent of the white patients were of ages 45 years and over com pared with only 32 percent of all other patients (table 4). Patients under 15 years of age ac counted for 11 percent of all white patients discharged and 6 percent of the days of care, compared with 13 percent and 9 percent, re spectively, for all other patients (tables 4 and 5). On the other hand, for age group 65 years and over white patients utilized 24 percent of the discharges and 36 percent of the days of care compared with 14 percent and 24 percent, re spectively, for all other patients. These patterns of hospital utilization were also evident by color and sex.
Of the white patients discharged, 40 percent were males and 60 percent were females; of the "all other" color group, 36 percent were males and 64 percent were females. The distribution of days of care for patients by sex and color was similar for white and all other patients.
As was mentioned previously, HDS data by color are limited because of the large number of patients for whom color was not identified. Nevertheless, for patients with color not stated the percent distributions by age for discharges (table 4), days of care (table 5), and average lengths of stay (table 6 and figure 1) were more like those of the white patients than of all other patients discharged. These relationships suggest that patients with color not stated were prob ably distributed by color in about the same proportions as those for whom color was identified, since white patients in the civilian noninstitu tionalized population outnumbered the all other patients by almost 7 to 1.

Geographic Region of Hospital
Discharges from short-stay hospitals by geo graphic region in 19 76 ranged from 5.5 million in the West Region and 7.5 million in the Northeast Region to about 10.7 million in the North Central Region and also the South Region (table 7). The regional differences in number of dis charges were mainly due to variations in the re gional population sizes (appendix I, table II) and partly to variations in discharge rates.
The regional discharges per 1,000 population in 1976 were 147 in the West, 154 in the Northeast, 159 in the South, and 187 in the North Central. Among the geographic regions, dis charge rates in the North Central Region were highest for all discharges and for each age group by sex. Higher discharge rates in the North Central Region than in the South Region re sulted in about the same numbers of discharges from both regions even though the population of the South was almost a fifth larger than of the North Central Region.
The rates of days of care ranged from 913 days per 1,000 population in the West Region to 1,476 in the North Central Region (table 8). The rates of hospital days for all age groups and by sex were also smallest in the West Region and highest in the North Central Region.
Average lengths of stay by geographic region were 8.9 days in the Northeast, 7.9 days in the North Central, 7.1 days in the South, and 6.2 days in the West Region (table 9). Hospitaliza tion was longest in the Northeast Region and  Figure 1. Average length of stay for patients discharged from short-stay hospitals, by age and color: United States, 1976 shortest in the West Region for patients of all age groups and by sex. Regional differences in average lengths of stay by age group and sex were largest among the older age groups.

Bed Size of Hospital
The number and percent distributions of dis charges and of days of care for patients dis charged from short-stay hospitals are shown by bed size of hospital and age of patient, according to sex, in tables 10 and 11.
Discharges from short-stay hospitals were about 40 percent male and 60 percent female in every hospital bed-size group, based on the un rounded data for the discharges shown in table 10. However, there were variations in the proportions of male and female by age group. These distributions of sex by age group were also ap proximately the same for every hospital bed-size group. For example, discharges for males under age 15 were within the narrow range of 55 to 58 percent and females, 42 to 45 percent of all discharges among the various hospital bed-size groups.
Days of care by age, sex, and bed size of hospital were distributed in a fashion similar to discharges. However, for all patients and for pa tients aged 15-44 years, by bed size of hospital, males accounted for a larger percentage and fe-, males for a smaller percentage of the days of care than of the discharges. These differences were the result of relatively short average lengths of stay for the large number of women hospital ized for obstetrical conditions during the childbearing years.
There were variations in the distributions by age of patients discharged, by bed size of hospi tal. Patients age 15-44 years accounted for 39 percent of the discharges from hospitals with 6-99 beds and 44 percent in hospitals with 500 beds or more (table 10). In contrast, patients age 65 years and over represented 28 percent of the discharges from the smallest hospitals and only 19 percent of the discharges from the larg est ,hospitals.
There were relatively small changes in the percentages of total discharges by size of hospital for patients of ages under 15 years and 45-64 years. These patterns by age were also applicable to females, but for males the percentages increased with size of hospital for age group 45-64 years, decreased with size of hospital for age group 65 years and over, and re mained about the same for age groups under 15 years and 15-44 years. Computations of per centages for the data in table 13 indicate similar age distribution patterns for discharges and days of care by size of hospital and geographic region.
Percent distributions of days of care for pa tients hospitalized changed by size of hospital in about the same direction as for discharges (table  11). As for discharges, changes were larger for patients aged 15-44 years and patients aged 65 years and over.
Average length of stay for patients of shortstay hospitals in 1976 increased consistently with size of hospital from 6.1 days in hospitals with 6-99 beds to 8.6 days in hospitals with 500 beds or more (table 12). The increase in average stay from the smallest to the,largest hospitals for males was from 6.3 days to 9.4 days and for fe males from 6.0 days to 8.1 days. Excluding deliveries, average length of stay for females increased with bed size of hospital from 6.4 days for the small hospitals to 8.8 days for the large hospitals.
Average lengths of stay by sex, age, and bed size of hospital are shown in table 14 for each geographic region. .

Type of Ownership 6f Hospital
Approximately 7 out of 10 patients of non-Federal short-stay hospitals were discharged from voluntary nonprofit hospitals operated by church and other nonprofit groups during every year the HDS was conducted. In 1976, volun tary nonprofit hospitals provided medical care to an estimated 24.7 million patients, or 72 percent of all patients hospitalized. Hospitals oper ated by State and local governments cared for 7.0 million patients, or 20 percent of ah dis charges, and proprietary hospitals operated for profit cared for 2.7 million patients, or about 8 percent of ah discharges (table 15).
The estimated 260.3 million days of care utilized by patients of short-stay hospitals duri ing 1976 were distributed by ownership of hos : pita1 in the following proportions: voluntary nonprofit, 74 percent; government, 19 percent; and proprietary, 7 percent (table 16).
Average lengths of stay were 7.8 days in voluntary nonprofit hospitals, 6.9 days in gov ernment hospitals, and 7.0 days in proprietary hospitals (table 17).

HOSPITAL UTILIZATION BY DIAGNOSIS
Diseases of the circulatory system ranked first in 1976 among the ICDA diagnostic classes as a principal or first-listed diagnosis among pa tients discharged from non-Federal short-stay hospitals (table 18). These conditions accounted for an estimated. 4.6 million discharges. Other leading ICDA diagnostic classes were diseases of the digestive system (4.2 million discharges); complications of pregnancy, childbirth, and the. puerperium (4.0 million discharges); accidents, poisonings, and violence (3.6 million discharges); diseases of the respiratory system (3.5 million discharges); and diseases of the genitourinary system (3.4 million discharges). These six ICDA classes included about 68 percent of the patients discharged from non-Federal short-stay hospitals.
The diagnostic categories presented in this summary report were selected because of their large frequencies as principal or first-listed diag noses or because the conditions are of special interest.
Some conditions such as malignant neoplasms, benign neoplasms, diseases of the urinary system, and fractures are presented as single categories without showing the specific diagnostic inclusions.
The number and rate of discharges and average length of stay for selected first-listed nonob stetrical diagnoses in 1976 are shown by sex in table A. The diagnostic categories of ischemic heart disease, mahgnant neoplasms, fractures, diseases of the urinary system, and benign neo plasms accounted for about one out of five (19 percent) patients discharged.
The number and rate of discharges and average length of stay for selected diagnostic cate gories in 1976 are compared with 1970 and 1975 in table B. The conditions selected for this  table account for about a third of the discharges from short-stay hospitals during 1976.
There were changes in the estimates of num bers and rates of discharges for some diagnostic categories from 1970 to 1976. For example, the rate per 1,000 population increased for ischemic - The total estimated rates of discharge from short-stay hospitals were higher for each older age group. Diagnostic classes with higher dis charge rates for older age groups included dis eases of the circulatory system, diseases of the digestive system, and diseases of the genitouri nary system (table 18). For infective and para sitic diseases and for diseases of the respiratory system, however, the youngest and oldest age groups had the highest discharge rates. Patients hospitalized for complications of pregnancy, childbirth, and the puerperium were almost all (over 99 percent) between the agesof 15 and 44 years.
Discharge rates increased with age for some conditions such as malignant neoplasms and acute myocardial infarction, but for other cate gories, as hypertrophy of tonsils and adenoids and for appendicitis, rates were higher for the younger than for the older age groups. Another variation by age group was seen in highest rates for the youngest and oldest ages for some condi tions-pneumonia and acute upper respiratory infections. However, rates were lowest for the youngest and oldest age groups for other condi tions-disorders of menstruation and displace ment of intervertebral disk.
The leading ICDA classes for each age group are presented in figure 2. The three leading classes for each age group represented from 46 percent of the discharges for age group 45-64 years to 57 percent for ages 15 years and under. Diseases of the respiratory system and diseases of the digestive system were among the five lead ing diagnostic classes of every age group. Never theless, among the selected diagnostic categories shown in table 18, for diseases of the respiratory  system by diagnostic category and age, the dis  charge rates for age groups under 15 years and  15-44 years were highest for hypertrophy of  tonsils and adenoids and for age groups 45-64 years and 65 years and over were highest for pneumonia. Among diseases of the digestive sys tem, appendicitis and inguinal hernia, with the same discharge rates, were the leading diagnoses for age group under 15 years. Appendicitis was also the leading digestive system diagnosis for age group 15-44 years. For age groups 45-64 years, and 65 years and over, discharge rates were highest for cholelithiasis.
The leading ICDA classes for patients under 15 years of age, measured by discharge rates per 1,000 population, were diseases of the respira tory system (22); accidents, poisonings, and violence (11); and diseases of the digestive sys tem (7). For the more detailed diagnostic cate gories, discharge rates were highest for hypertrophy of tonsils and adenoids (9), pneumonia (4), and fractures (4). Average lengths of stay for these conditions were 1.8 days, 5.5 days, and 6.0 days, respectively (table 18).
The leading diagnostic classes for age group 15-44 years and the corresponding discharge rates per 1,000 population were complications of pregnancy, childbirth, and the puerperium (43); accidents, poisonings, and violence (18); and diseases of the genitourinary system (18). Some of the leading nonobstetrical diagnostic categories were diseases of the urinary system (5), fractures (4), and benign and unspecified neoplasms (4). Average lengths of stay for these categories were 5.4 days, 8.3 days, and 5.2 days, respectively.
For age group 45-64 years, discharge rates per 1,000 population were highest for the ICDA classes diseases of the circulatory system (38), diseases of the digestive system (3 l), and dis eases of the genitourinary system (21). The diagnostic categories with the highest discharge rates for this age group were malignant neo plasms (15), chronic ischemic heart disease (1 l), and diseases of the urinary system (7). The cor responding average lengths of stay were 13.0 days, 8.7 days, and 8.0 days, respectively. Discharge rates for age group 65 years and over were highest per 1,000 population for the ICDA classes diseases of the circulatory system (107), diseases of the digestive system (47), and neoplasms (39). Some of the diagnostic cate gories with high discharge rates were malignant neoplasms (35), chronic ischemic heart disease (33), and cerebrovascular disease (2 1). The rates for these conditions for patients 65 years and over compared with age group 45-64 years were more than double for malignant neoplasms, about three times greater for chronic ischemic heart disease, and six times greater for cerebro vascular disease.
Average lengths of stay for patients aged 65 years and over varied among the selected diag nostic categories from 3.7 days for disorders of menstruation, 5.0 days for cataract, and 5.1 days for diseases of the ear and mastoid process to 16.6 days for fractures, 15.3 days for diseases of the central nervous 'system, and 14.3 days for acute myocardial infarction. Average length of . stay for patients age 65 and over was longest for fractures, because about 42 percent of these were for fractures of the neck of the femur for which patients were hospitalized an average of 21.3 days in 1976.

\
The number and rate of inpatients dis charged from short-stay hospitals and average length of stay, by ICDA classes and selected diagnostic categories, are presented by sex for 1976 in table 19.
The diagnostic classes with the largest num bers of principal, or first-listed diagnoses, for males in 1976 were diseases of the circulatory system (2.3 million discharges), diseases of the ' digestive system (2.0 million discharges); and accidents, poisonings, and violence (2.0 million discharges). For females, the leading ICDA classes were complications of pregnancy, childbirth, and the puerperium (4.0 million dis charges); diseases of the genitourinary system (2.4 million discharges); and diseases of the,,cir culatory system (2.3 million discharges). Ap proximately 46 percent of the first-listed diag noses for males and 42 percent for females were in the three leading ICDA classes for each . sex* S .' .
The diagnostic categories with the highest frequencies in 1976 are shown by sex in table A. Annual rates of discharge per 1,000 population for males were highest for the diagnostic cate gories of ischemic heart disease (ll), malignant neoplasms (7), fractures (6), diseases of the uri nary system (5), and inguinal hernia (4). For fe males, some of the diagnostic categories with high discharge rates were malignant neoplasms (8), ischemic heart disease (8)) diseases of the urinary system (6), benign and unspecified neo plasms (6), and disorders of menstruation (5).
Discharge rates for some diagnostic cate gories were much higher for one sex than for the other. Rates were higher for males than for fe males with first-listed diagnoses of inguinal hernia, alcoholism, and acute myocardial infarc tion. The rates for females were higher than for males with benign neoplasms, cholelithiasis, and diabetes mellitus.
Average length of stay by the ICDA diag nostic classes varied for males from 4.4 days for symptoms and ill-defined conditions and 6.1 days for diseases of the nervous system and sense organs to 12.0 days for certain causes of perinatal morbidity and 11.6 days for neoplasms (table 19). Average hospital stays for females ranged from 3.8 days for complications of preg nancy, childbirth, and the puerperium and 4.8 days for symptoms and ill-defined conditions to 14.5 days for certain causes of perinatal morbid ity and 10.9 days for diseases of the circulatory system. Average lengths of stay for the selected diagnostic categories were shortest for males and females with hypertrophy of tonsils and ade noids and with diseases of the ear and mastoid process. Average hospital stays for males and females were longest for acute myocardial in farction and for cerebrovascular disease.

Color
Data on discharges and average length of stay for patients for whom color was identified are presented in table 19 by diagnostic classes and selected categories of first-listed diagnoses. Discharge rates were not computed because of the large number of patients (4.4 million) for whom color was not identified. Among the leading ICDA diagnostic classes for both white and all other patients, but not in the 'same order, were diseases'of the circulatory system; diseases of the digestive system; compli cations of pregnancy, childbirth, and the puer perium; accidents, poisonings, and violence; and diseases of the respiratory system. Measured as percentages of total discharges, the largest dif ference by color was for complications of preg nancy, childbirth, and the puerperium which accounted for 10 percent of all white patients discharged compared with 19 percent of all other patients discharged. Other large differ ences in the proportions of total discharges by ICDA class and color were for diseases of the circulatory system which represented 14 percent of the discharges for white patients and 10 percent for all other patients and for diseasesof the digestive system which represented 13 percent of the white patients discharged and 10 percent of all other patients.
The number and percent of total discharges and average length of stay are shown by color of 10 patients for selected diagnostic categories in table C. Discharges of white patients with firstlisted diagnostic categories such as ischemic heart disease, malignant neoplasms, and chole lithiasis as percentages of ail discharges were higher ,than for all other patients. For all other patients the proportions of total discharges with first-listed diagnoses of diabetes mellitu's, benign neoplasms, and alcoholism were highef than for white patients.
Average lengths of stay for almost all the ICDA classes and the selected diagn&t@ c&e gories were shorter for white than for all other patients (tables 19 and C).

Geographic Region of Hospital
Diseases of the circulatory system were high est in number of first-listed diagnoses in every geographic region (table 20). Complications of pregnancy, childbirth, and the puerperium and diseases of the digestive system ranked either second or third among the ICDA classesin each geographic region except in the West Region where accidents, poisonings, and violence ranked third and diseasesof the digestive system ranked fourth.
The number of discharges per 1,000 in 1976 ranged from 147 in the West Region to 187 in the North Central Region. The smallest fluctu ations in the discharge rates per 1,000 popula tion among. the geographic regions were for appendicitis for which the rates ranged from 1.3 in the Northeast to 1.5 in the North Central, for lacerations from 1.4 in the Northeast to 1.7 in the West, and for hyperplasia of the prostate from 1.0 in the South to 1.3 in the North Cen tral.
Some of the diagnostic categories for which there were large variations in rates among the regions were diabetes mellitus for which the discharge rate ranged from 1.6 in the West Re gion to 3.2 in the North Central Region, for acute upper respiratory infections from 0.8 in the West Region to 1.8 in the South Region, and for displacement of intervertebral disk from 1.2 in the Northeast Region to 2.5 in the West Region.
As during previous years, there were differ ences among the geographic regions in the average lengths of stay for patients in short-stay hospitals. In 1976, the average length of stay ranged from 6.2 days in the West Region to 8.9 days in the Northeast Region (table 20). Short hospital stays in the West Region and long stays in the Northeast Region were also evident for most of the diagnostic classes and the selected diagnostic categories.

Bed Size of Hospital
The number of patients discharged from short-stay hospitals during 1976 and average length of stay are shown by bed size of hospital and diagnostic category in table 2 1. Approxi mately 51 percent of the discharges were from hospitals with fewer than 300 beds and 49 percent from hospitals with 300 beds or more (table D). The proportion of different diagnostic con ditions treated in hospitals varied by size of hos pital, As is shown in table D, greater proportions of patients were treated in hospitals with fewer than 300 beds for infective and parasitic diseases, diseases of the respiratory system, and diseases of the digestive system than in hospitals with 300 beds or more. Greater proportions of the discharges were from the larger than from the smaller hospitals for neoplasms, congenital anomalies, and certain causes of perinatal mor bidity.
Average length of stay increased with size of hospital from 6.1 days for patients discharged from hospitals with fewer than 100 beds to 8.6 days for patients from hospitals with 500 beds or more. This relationship of average length of stay to size of hospital occurred for most of the ICDA classes and diagnostic categories presented in table 21.

All-Listed Diagnoses
An estimated 65.9 million diagnoses were recorded for the 34.4 million inpatients of non-Federal short-stay hospitals in 1976 (table 22) for an average of 1.9 diagnoses per patient. The average number of diagnoses per discharge was    (table G). While these rates for males also increased with advancing age, for females the an nual rates of operations per 1,000 population were about the same for age groups 15-44 years (140), 45-64 years (141), and 65 years and over (138). The surgical rate for women aged 15-44 years was as high as for older women because of the large number of women operated on for ob stetrical and gynecological conditions in the 15-44-year group.
The surgical operations are grouped in the detailed tables of this report by the 17 ICDA surgical classes, including biopsy. Operations within these classes are presented by surgical categories. Although biopsy is shown as a surgi cal class, it is treated as a surgical category in this report.
The surgical categories shown in table 23 were highest for biopsy (1,116,OOO procedures), diagnostic dilation and curettage of uterus (983,000 procedures), hysterectomy (678,000 13 procedures), tonsillectomy (629,000 proce dures), and repair of inguinal hernia (507,000 procedures). These were also the leading surgi cal categories in 1975 and in the same order of frequency.3 The estimated numbers and rates for select ed surgical categories in 1976 are compared with the data for 1970 and 1975 in  14 to 3. Surgical rates remained about the same during this period for many of the surgical cate gories, as, for example, prostatectomy and hemorrhoidectomy.

Sex and Age
The Abdominal surgery, orthopedic surgery, and otorhinolaryngology were among the five lead ing surgical specialties for males and females (figure 3). Rates per 1,000 population for these surgical specialties varied slightly by sex. In addition, urological surgery and vascular and car diac surgery for males and gynecological surgery 362   I  I  I  I  I  I  I  I   0  5  10  15  20  25  30  35  40 NUMBER OF OPERATIONS PER l,OW PERSONS PER YEAR Figure 3. Rate of all-listed operations for patients discharged from short-stay hospitals, by the leading ICDA surgical classes and sex: United States, 1976 and obstetrical procedures for females were also among the five leading specialties. The number of operations per 1,000 popula tion for males was highest for the surgical cate gories repair of inguinal hernia (4), biopsy (4), and tonsillectomy (3). The rates for females were highest for diagnostic dilation and curet tage of uterus (9), biopsy (7), and hysterectomy (6). Rates per 1,000 population were higher for males than for females operated on for repair of inguinal hernia (4 compared with less than l), and closed reduction of fracture without fixa tion (2 compared with 1). Rates for females were higher than for male patients for some surgical categories as mastectomy (3 compared with less than I), cholecystectomy (3 compared with l), and biopsy (7 compared with 4).
The surgical categories with the largest fre quencies for patients of ages 15 years and over were biopsy (1,084,OOO operations), diagnostic dilation and curettage of uterus (980,000 opera tions), hysterectomy (675,000 operations), oophorectomy and salpingo-oophrectomy (448,000 operations), and cholecystectomy (442,000 operations). Patients of age group 15 years and over accounted for about 89 percent of all the operations performed in non-Federal short-stay hospitals during 1976.

Color
The five leading surgical classes for white pa tients and also for all other patients included gynecological, abdominal, orthopedic, and uro logical surgery. In addition, for white patients otorhinolaryngology ranked fourth and for all other patients obstetrical procedures ranked sec ond (table 23).
The largest difference by color was for ob stetrical procedures which accounted for only 6 percent of all surgical procedures for white pa tients compared with 13 percent for all other patients. The proportions of total operations for white patients were smaller than for all other patients with operations in the surgical cate gories cesarean section, dilation and curettage after delivery or abortion, and repair of obstetri cal laceration. The proportions of total opera tions were larger for white than for all other pa tients with operations in the surgical categories repair of inguinal hernia, cholecystectomy, and prostatectomy.

Geographic Region of Hospital
The number of operations for patients dis-,, charged from short-stay hospitals by surgical class, surgical category, and geographic region are presented in table 25. The corresponding surgical rates are shown in table 26. The num ber of operations per 1,000 population was low est in the South Region (84) and was highest in the North Central Region (110).
Surgical rates in all regions were highest for the four surgical classesof gynecological surgery, abdominal surgery, orthopedic surgery, and otorhinolaryngology.
Urological surgery ranked among the five leading specialties in all regions .' except the Northeast Region, where obstetrical procedures ranked fifth.
There were differences in the rates for the surgical classes among the geographic regions. Some examples are dental surgery for which the rates per 1,000 population ranged from less than 1 per 1,000 population in the West Region to 3 in the Northeast Region, otorhinolaryngology which ranged in rates from 6 in the South Region to 11 in the North Central Region, and for ophthalmology the range was 'from 3 in the . South Region to 5 in the North Central Region (table 26).
Operations performed in large numbers in all geographic regions included the surgical cate gories of biopsy, diagnostic dilation and curet tage of uterus, hysterectomy, tonsillectomy, repair of inguinal hernia, and cholecystectorny. Some examples of regional differences in the rates of operations per 1,000' population by surgical category are biopsy which ranged. from 4 in the South Region to 6 in the North Central Region; diagnostic dilation and curettage of uterus, from 3 in the West Region to 6 in the Northeast Region; and hysterectomy, from 2 in the Northeast Region to 4 in the South Region.

Bed Size of Hospital
The number .of operations patients underwent in short-stay hospitals in 1976 is presented, in table 27 for each surgical class and category by bed size of hospital where the surgery was performed. The percent distributions of opera tions and of discharges by bed size of hospital are shown in table J.
Hospitals with fewer than 200 beds ac counted for a smaller percentage of the total 16 -- number of operations performed (28 percent) than of the total discharges (36 percent). The proportions of total operations and of dis charges in hospitals with 200-299 beds were about the same. Hospitals with 30b beds or more accounted for 55 percent of all operations performed in short-stay hospitals compared with 49 percent of the patients discharged.
Greater proportions of all operations were performed in hospitals with 300 beds or more than in hospitals with fewer than 300 beds. Al-. though hospitals with 300 beds or more treated an estimated 49 percent of the patients hospi talized in short-stay hospitals during 1976, the proportions of total operations for the surgical~ specialties varied from 50 to 74 percent (table K). The proportions of total operations were about equally divided between the. smaller and larger hospitals for the specialties plastic surgery, abdominal surgery, proctological surgery, and gynecological surgery. Specialties 'with the larg est percentages of the operations performed in hospitals with 300 beds or more were vascular and cardiac surgery (74 percent), neurosurgery (66 percent), thoracic surgery (65 percent), and oral and maxillofacial surgery (64 percent).

R O M N O N F E D E R A L S H O R T -S T A Y HOSPITALS. E X C L U D E S N E W B O R N INFANTS) N O R T H E A S T N O R T H C E N T R A L S O U T H I W E S T , S E X A N D A G E T O T A L
loo-5 0 0 lo o5 0 0 -6-99 4 9 9 B E D S 6-99 4 9 9