National Institute on Alcohol Abuse and Alcoholism
Division of Epidemiology and Prevention Research
Alcohol Epidemiologic Data System

SURVEILLANCE REPORT #80

TRENDS IN ALCOHOL-RELATED MORBIDITY
AMONG SHORT-STAY COMMUNITY HOSPITAL
DISCHARGES, UNITED STATES, 1979–2005

Chiung M. Chen, M.A.
Hsiao-ye Yi, Ph.D.

CSR, Incorporated¹
Suite 1000
2107 Wilson Boulevard
Arlington, VA 22201

August 2007

U.S. Department of Health and Human Services
Public Health Service
National Institutes of Health

¹ CSR, Incorporated, operates the Alcohol Epidemiologic Data System (AEDS) under Contract No. N01AA32007 for the Division of Epidemiology and Prevention Research, National Institute on Alcohol Abuse and Alcoholism (NIAAA). Dr. Rosalind A. Breslow serves as NIAAA Project Officer on the contract and oversaw the preparation of this report.

HIGHLIGHTS

This surveillance report, prepared annually by the Alcohol Epidemiologic Data System (AEDS), National Institute on Alcohol Abuse and Alcoholism (NIAAA), presents data on alcohol-related morbidity in the United States from 1979 to 2005. AEDS compiles these statistics on alcohol-related inpatient stays based on a national sample of hospital discharge episodes from the National Hospital Discharge Survey (NHDS), conducted annually by the National Center for Health Statistics (NCHS). Civilian population data estimated by the U.S. Census Bureau are used as the denominators to calculate rates. The following are highlights of general trends and notable findings:

Alcohol-Related Hospital Discharges in 2005

• Approximately 441,000 hospital discharge episodes for persons ages 15 and older had a principal (first-listed) alcohol-related diagnosis, and approximately 1.6 million discharge episodes had an any (all-listed) alcohol-related diagnosis. These figures represent 18.8 principal (first-listed) and 69.7 any (all-listed) alcohol-related discharges per 10,000 population, about the same in the principal (first-listed) alcohol-related discharge rate and a slight decrease in the any (all-listed) alcohol-related discharge rate compared with the 2004 rates (18.7 and 71.2, respectively).

• For the first time, alcoholic psychoses surpassed alcohol dependence syndrome and became the largest group (36 percent) of principal (first-listed) diagnoses, followed by alcohol dependence syndrome (30 percent), cirrhosis of the liver (26 percent), and nondependent abuse of alcohol (8 percent).

• A substantial difference exists between rates based on principal (first-listed) and any (all-­listed) diagnoses. As much as three-quarters (73.0 percent) of alcohol-related morbidity episodes did not appear as a principal (first-listed) diagnosis.

• Alcohol-related diagnoses in decreasing order of severity, as measured by average length of hospital stay, were cirrhosis (5.9 days, with 5.8 days for alcoholic cirrhosis), alcohol dependence syndrome (4.7 days), alcoholic psychoses (4.6 days), and nondependent abuse of alcohol (2.4 days).

General Trends

• Hospital discharge rates showed a clear upward trend for both principal (first-listed) and any (all-listed) alcoholic psychoses as well as all chronic liver disease and cirrhosis, and for any (all-listed) nondependent abuse of alcohol during 1988 to 2005. In contrast, there was an downward trend for both principal (first-listed) and any (all-­listed) alcohol dependence syndrome between 1995 and 2005.

• For all alcohol-related diagnoses, except cirrhosis without mention of alcohol, hospital discharge rates continue to be higher for males than for females. Persons ages 45 to 64 generally have the highest principal (first-listed) as well as any (all-listed) alcohol-related morbidity rates, and persons ages 15 to 24 have the lowest alcohol-related morbidity rates.

• In terms of percentage shares, alcohol dependence syndrome was the largest group of principal (first-listed) alcohol-related diagnoses prior to 2005. However, its percentage share declined substantially from more than 70 percent in 1979 to 30 percent in 2005. The percentage shares of diagnoses for alcoholic psychoses and any cirrhosis increased during the 27-year study period. Alcoholic psychoses outnumbered any cirrhosis since 1994 and surpassed alcohol dependence syndrome as the largest principal (first-listed) alcohol-related diagnoses in 2005.

• On average, principal (first-listed) alcohol-related diagnoses accounted for slightly over one-third (37 percent) of all alcohol-related diagnoses over the 27-year study period.

• While there has been relatively little change in the percentage of hospital discharges with principal (first-listed) mention of an alcohol-related diagnosis, the proportion of hospital discharges with any (all-listed) mention of an alcohol-related diagnosis has increased.

• For alcohol dependence syndrome and cirrhosis, reductions in average length of stay were observed since 1988 but leveled off in the past few years.
  

INTRODUCTION

This is the fifteenth surveillance report on trends in alcohol-related morbidity among patients discharged from short-stay community hospitals in the United States. Prepared by AEDS, NIAAA, the report updates the trends published in earlier surveillance reports. The findings are intended to be useful to policymakers, health care providers, researchers, and other individuals concerned about the health effects of alcohol abuse.

Data are presented by age and sex, including numbers and population-based rates for hospital discharges with principal (first-listed) mention or any (all-listed) mention of specific diagnoses for chronic diseases resulting from alcohol abuse. Also included are data on the average length of hospital stay for alcohol-related discharge episodes. Race-specific data are not reported because a large proportion of discharges do not include race information.

AEDS uses variance estimation procedures recommended by NCHS to develop 95 percent confidence intervals for each estimate shown in figure 5 through figure 9 based on relative standard errors. The values of all estimates are presented in tables.

DATA

Sources

Hospital discharge data for the report are obtained from the NHDS, conducted annually by NCHS since 1965. These data are processed by NCHS and made available on public use computer files. The report begins with 1979, the year in which the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) was implemented. ICD-9-CM is a diagnostic coding scheme published by the Commission on Professional and Hospital Activities (1978) and is based on the World Health Organization’s ninth revision of the ICD (1977). The Tenth Revision of ICD (ICD-10) was implemented for mortality data beginning with data year 1999; the implementation of ICD-10-CM for morbidity data has not yet been determined (NCHS 2007).

The NHDS collects data from a sample of non-Federal, short-stay hospitals with six or more beds and an average length of stay fewer than 30 days. The sample is stratified by geographic region and hospital size. The probability of selecting a hospital is directly proportional to its size. Discharge episodes are sampled randomly at each participating hospital; the episode sampling ratio within an individual hospital varies inversely with the probability of hospital selection. NCHS calculates appropriate weights and includes them in the data files to project national estimates from the sample. Descriptions of the NHDS sampling design, data collection procedures, and data collection instruments used during the 1979–1987 period are published elsewhere by NCHS (1977, 2004, 2005, 2006, 2007).

In 1988 NCHS implemented a new sample design to (1) provide geographic sampling comparability with other surveys conducted by NCHS, (2) update the sample of hospitals selected for the survey, and (3) maximize the use of data collected through automated systems. This change in the sample design may affect trend data because some differences between NHDS statistics based on the earlier sample (1979–1987) and statistics based on the 1988 sample may be due to sampling variability rather than changes in patterns of hospital utilization (NCHS 2004, 2005, 2006, 2007). For example, NCHS compared the old survey results with the new results and produced significantly lower estimates of principal (first-listed) and any (all-listed) diagnoses of alcohol dependence in the new series (Haupt and Kozak 1992).

For each hospital discharge episode in the sample, the following items are provided: the patient’s age, sex, race, marital status, and length of stay; the hospital’s size and regional location; and codes for up to seven diagnoses and up to four surgical procedures.

Civilian population data used in calculating hospital discharge rates were estimated by the U.S. Census Bureau and provided by the NCHS.

Limitations

Estimates of alcohol-related morbidity based on the NHDS sample may underestimate the overall prevalence of such morbidity in the general U.S. population. For example, the NHDS sample does not include Veterans Administration and other Federal hospitals or hospitals where the average length of stay is 30 days or longer. Morbidity among individuals who are not hospitalized (i.e., those who seek outpatient treatment or no treatment) also is not reflected in the NHDS data. Furthermore, the stigma associated with alcohol abuse may lead to some reluctance by health professionals to report an alcohol-related diagnosis.

To properly interpret the data, the following characteristics of the NHDS should be understood:

• The NHDS provides a record for each sampled hospital discharge episode, not for each individual patient; therefore, an unknown portion of discharge episodes may reflect multiple hospital episodes for a single patient in a given year. Because no patient identifiers appear in the NHDS public use data files, it is not possible to identify records for different hospital episodes involving the same patients. Consequently, the numbers and rates reported here reflect the incidence of alcohol-related hospital discharge episodes and not the prevalence of alcohol-related diagnoses among individual patients.

• Because NHDS data are obtained from a sample of hospital discharge episodes, any resulting estimates are subject to sampling error. The reliability of estimates is a function of sample size. NCHS guidelines, based on the NHDS sampling plan, require a minimum of 30 unweighted cases for even marginally acceptable reliability. In this report, data based on fewer than 30 NHDS records (population estimates in the range of 5,000 to 6,000 after weights are applied) are not displayed for table cells. Estimates below 10,000 may be only marginally reliable.

• The NHDS methodology allows for coding up to seven different diagnoses for each hospital discharge record. The first of these code positions contains a code for the principal (first-listed) diagnosis. The remaining six positions can be used to code additional diagnoses identified during the patient's hospital stay. In this report, an any (all-listed) diagnosis is a diagnosis that appears in any one of the seven possible code positions for each record; counts of an any (all-listed) diagnosis are described as counts for any mention of the particular diagnosis. The principal (first-listed) diagnosis need not be the most serious diagnosis recorded on a discharge record, nor is it necessarily the diagnosis that accounts for the overall length of a patient's hospital stay.

• Numbers and rates based only on principal (first-listed) diagnoses can be misleading because these data overlook other morbidity that may be diagnosed during the patient's hospitalization. Therefore, numbers and rates are presented for principal (first-listed) and any (all-listed) mentions of alcohol-related diagnoses. Principal (first-listed) diagnoses constitute a subset of any (all-listed) diagnoses. While diagnostic categories based on principal (first-listed) diagnoses are mutually exclusive, a given discharge may appear in more than one category based on any (all-listed) diagnoses. However, a hospital discharge with multiple diagnoses in the same category is not counted more than once. For example, one diagnostic category is alcoholic psychoses (ICD-9-CM code 291). Under this category are eight subclassifications. A discharge with diagnoses of both alcohol withdrawal delirium (code 291.0) and alcohol withdrawal hallucinosis (code 291.3) would be counted only once under the overall alcoholic psychoses classification even though more than one type of alcoholic psychosis appears on the record.

• Two data collection procedures have been used since 1985 in conducting the survey: (1) a manual system of sample selection and data abstraction and (2) an automated method that involves the purchase of data files from abstracting service organizations. An increasing proportion of respondent hospitals have employed the automated method. Prior to 1985, all data were collected manually. In 1987 approximately one-sixth (17 percent) of sample hospitals used the automated method. By 2005 44 percent of these hospitals were using the automated method (DeFrances and Hall 2007). The variability in data collection procedures may have systematic effects on morbidity trend data.

• The change in sample design implemented in 1988 implies a discontinuity in time-series data. Therefore, the reader must use caution when interpreting trends across the old and the new sample periods.

METHOD

Definitions

A major methodological issue of this report is the specification of the categories of alcohol-related diagnoses. The level of diagnostic detail defined in the ICD-9-CM and available in the NHDS is so great that the most detailed classification of morbidity results in diagnostic categories with very few observations. To minimize the problem of small cell sizes, detailed diagnostic classifications from the NHDS are reported under four major alcohol-related categories, with three subcategories for chronic liver disease and cirrhosis. These categories (and the associated specific alcohol-related diagnoses) are listed in the table of definitions below. The categories are consistent with the diagnostic categories used in previous AEDS publications on alcohol-related morbidity.

Definition of Alcohol-Related Diagnoses

Category Used in Report	Classification in ICD-9-CM
Alcoholic psychoses	291.0 Alcohol withdrawal delirium 291.1 Alcohol amnestic syndrome 291.2 Other alcoholic dementia 291.3 Alcohol withdrawal hallucinosis 291.4 Idiosyncratic alcohol intoxication 291.5 Alcoholic jealousy 291.8 Other specific alcoholic psychosis 291.9 Unspecified alcoholic psychosis
Alcohol dependence syndrome	303.0 Acute alcohol intoxication 303.9 Other and unspecified alcohol dependence 265.2 Pellagra 357.5 Alcoholic polyneuropathy 425.5 Alcoholic cardiomyopathy 535.3 Alcoholic gastritis
Nondependent abuse of alcohol	305.0 Alcohol abuse
Chronic liver disease and cirrhosis: Alcoholic cirrhosis of the liver Other specified cirrhosis of the liver without mention of alcohol Unspecified cirrhosis of the liver without mention of alcohol	571.0 Alcoholic fatty liver 571.1 Acute alcoholic hepatitis 571.2 Alcoholic cirrhosis of liver 571.3 Alcoholic liver damage, unspecified 571.4 Chronic hepatitis 571.6 Biliary cirrhosis 571.8 Other chronic nonalcoholic liver disease 572.3 Portal hypertension 571.5 Cirrhosis of liver without mention of alcohol 571.9 Unspecified chronic liver disease without mention of alcohol

For chronic liver disease and cirrhosis, the ICD-9-CM allows for a distinction between diagnoses with and without mention of alcohol. AEDS has chosen not to emphasize this distinction and has reported all liver cirrhosis in analyses of alcohol-related morbidity and mortality. This practice was adopted at the recommendation of health professionals and epidemiologists who attended a conference sponsored by AEDS in 1979. In keeping with this practice, this report includes an overall category of chronic liver disease and cirrhosis that does not distinguish between cirrhosis with and without mention of alcohol. For consistency with causes of death reported in other AEDS publications on cirrhosis mortality (Yoon and Yi 2007), this report also includes three subcategories of cirrhosis: (1) alcoholic cirrhosis of the liver, (2) other specified cirrhosis of the liver without mention of alcohol, and (3) unspecified cirrhosis of the liver without mention of alcohol.

This report presents data for the U.S. population ages 15 and older in the following age categories: 15 to 24, 25 to 44, 45 to 64, and 65 and older. Age 15 is below the minimum legal drinking age in all 50 States and the District of Columbia, but survey results show that a large number of adolescents drink alcoholic beverages. For example, data from the NIAAA 2001–2002 National Epidemiologic Survey on Alcohol and Related Conditions indicate that 12.2 percent of current drinkers ages 18 and older in the United States began drinking at age 15 or younger (Alcohol Epidemiologic Data System 2004).

Exclusions

In assessing alcohol-related diagnoses, discharges of females with deliveries should be excluded because childbirth is not an illness. In a typical year, approximately 12 to 13 percent of all hospital discharges are for delivery. In 2005 this category accounted for 11.6 percent of all discharges (DeFrances and Hall 2007). Accordingly, to examine the share of all discharges associated with a principal (first-listed) or an any (all-listed) alcohol-related diagnosis in figure 4, the percentages were calculated after excluding from both the numerator and denominator all records coded in the principal (first-listed) diagnosis as V27, a supplementary ICD-9-CM classification for females delivering babies.

Assessment of Statistical Significance

Because data on hospital discharges are based on a sample of all discharges, there is some sampling error in the estimates presented in this report. To assess the statistical significance of apparent differences in the estimates presented, we have used variance estimation procedures recommended by the NCHS to develop confidence intervals for each estimate.

The confidence intervals presented in figures 5–9 are based on relative standard errors (RSEs), which are standard errors expressed as a percentage of the estimate. NCHS provides a method for obtaining RSEs in the technical documentation of the annual National Hospital Discharge Survey summary report for principal (first-listed) and any (all-listed) diagnoses and for length of stay (NCHS 2004, 2005, 2006, 2007). To obtain a 95-percent confidence interval, the RSE value was multiplied by the estimate and by 1.96, and the resulting value was then added to and subtracted from the estimate.

REFERENCES

Alcohol Epidemiologic Data System. Unpublished data from the 2001–2002 National Epidemiologic Survey on Alcohol and Related Conditions, National Institute on Alcohol Abuse and Alcoholism, 2004.

Commission on Professional and Hospital Activities. The International Classification of Diseases, Ninth Revision, Clinical Modification. Ann Arbor, Michigan, 1978.

DeFrances, C.J., and Hall, M.J.. 2005 National Hospital Discharge Survey. Advance Data, Number 371. Hyattsville, MD: National Center for Health Statistics, 2007.

Haupt, B.J., and Kozak, L.J. Estimates From Two Survey Designs: National Hospital Discharge Survey. National Center for Health Statistics. Vital and Health Statistics, Series 13, No. 111. Washington, DC: U.S. Government Printing Office, 1992.

National Center for Health Statistics (W.R. Simmons and G.A. Schnack). Development of the Design of the NCHS Hospital Discharge Survey. Vital and Health Statistics. Series 2, No. 39. U.S. Department of Health, Education and Welfare Publication No. (HRA) 77-1199. Health Resources Administration. Washington, DC: U.S. Government Printing Office, 1977.

National Center for Health Statistics. 1979–2002 National Hospital Discharge Survey (NHDS) Multi-Year Public Use Data File Documentation. Hyattsville, MD: NCHS, 2004.

National Center for Health Statistics. 2003 National Hospital Discharge Survey (NHDS) Public Use Data File Documentation. Hyattsville, MD: NCHS, 2005.

National Center for Health Statistics. 2004 National Hospital Discharge Survey (NHDS) Public Use Data File Documentation. Hyattsville, MD: NCHS, 2006.

National Center for Health Statistics. 2005 National Hospital Discharge Survey (NHDS) Public Use Data File Documentation. Hyattsville, MD: NCHS, 2007.

World Health Organization. Manual of the International Statistical Classification of Diseases, Injuries, and Causes of Death, Ninth Revision. Geneva: World Health Organization, 1977.

Yoon, Y.H., and Yi, H. Surveillance Report #79: Liver Cirrhosis Mortality in the United States, 1970–2004. Bethesda, MD: National Institute on Alcohol Abuse and Alcoholism, Division of Epidemiology and Prevention Research, 2007.

List of Figures

Figure 1. Percent distribution of principal (first-listed) diagnoses among discharges with principal (first-listed) mention of an alcohol-related diagnosis, 2005.

Figure 2. Trends in percent distribution of principal (first-listed) diagnoses among discharges with principal (first-listed) mention of an alcohol-related diagnosis, 1979–2005.

Figure 3. Percent distribution of principal (first-listed) diagnoses among discharges with any (all-listed) mention of an alcohol-related diagnosis, 2005.

Figure 4. Trends in percent of discharges with principal (first-listed) or any (all-listed) mention of an alcohol-related diagnosis among all discharges, 1979–2005.

Figure 5. Rates and 95-percent confidence intervals for principal (first-listed) alcohol-related diagnoses, 1979–2005.

Figure 6. Rates and 95-percent confidence intervals for any (all-listed) alcohol-related diagnoses, 1979–2005.

Figure 7. Rates and 95-percent confidence intervals for principal (first-listed) mention of specific alcohol-related diagnoses, 1979–2005.

Figure 8. Rates and 95-percent confidence intervals for any (all-listed) mention of specific alcohol-related diagnoses, 1979–2005.

Figure 9. Average length of stay and 95-percent confidence intervals for specific alcohol-related diagnoses, 1979–2005.

List of Tables

Table 1. Number and rate of principal (first-listed) alcohol-related diagnoses for U.S. population ages 15 years and older by sex and age group, 1979–2005.

Table 2. Number and rate of any (all-listed) alcohol-related diagnoses for the U.S. population ages 15 years and older by sex and age group, 1979–2005.

Table 3. Average length of stay (in days) for principal (first-listed) alcohol-related diagnoses by sex and age group, 1979–2005.

Figure 1. Percent distribution of principal (first-listed) diagnoses among discharges with principal (first-listed) mention of an alcohol-related diagnosis, 2005.

d

 

Figure 2. Trends in percent distribution of principal (first-listed) diagnoses among discharges with principal (first-listed) mention of an alcohol-related diagnosis, 1979–2005.

Note: Shaded area represents the period before implementation of a new sample design which may affect the trend data. Caution should be taken when assessing differences between the old and new sample design periods.

Data for figure 2 are presented in the following page.

 

Figure 3. Percent distribution of principal (first-listed) diagnoses among discharges with any (all-listed) mention of an alcohol-related diagnosis, 2005.

d

Figure 4. Trends in percent of discharges with principal (first-listed) or any (all-listed) mention of an alcohol-related diagnosis among all discharges, 1979–2005.

Note: Shaded area represents the period before implementation of a new sample design which may affect the trend data. Caution should be taken when assessing differences between the old and new sample design periods.

Data for figure 4 are presented in the following page.

 

Figure 5. Rates and 95-percent confidence intervals for principal (first-listed) alcohol-related diagnoses, 1979–2005.

[Vertical axes reflect rates per 10,000 population: scale is not uniform for all graphs]

[Shaded area represents the period before implementation of a new sample design which may affect the trend data. Caution should be taken when assessing differences between the old and new sample design periods.]

Data for figure 5 are presented in Table 1.

 

Figure 6. Rates and 95-percent confidence intervals for any (all-listed) alcohol-related diagnoses, 1979–2005.

[Vertical axes reflect rates per 10,000 population: scale is not uniform for all graphs]

[Shaded area represents the period before implementation of a new sample design which may affect the trend data. Caution should be taken when assessing differences between the old and new sample design periods.]

Data for figure 6 are presented in Table 2.

 

Figure 7. Rates and 95-percent confidence intervals for principal (first-listed) mention of specific alcohol-related diagnoses, 1979–2005.

[Vertical axes reflect rates per 10,000 population: scale is not uniform for all graphs]

[Shaded area represents the period before implementation of a new sample design which may affect the trend data. Caution should be taken when assessing differences between the old and new sample design periods.]

Data for figure 7 are presented in Table 1.

 

Figure 8. Rates and 95-percent confidence intervals for any (all-listed) mention of specific alcohol-related diagnoses, 1979–2005.

[Vertical axes reflect rates per 10,000 population: scale is not uniform for all graphs]

[Shaded area represents the period before implementation of a new sample design which may affect the trend data. Caution should be taken when assessing differences between the old and new sample design periods.]

Data for figure 8 are presented in Table 2.

 

Figure 9. Average length of stay and 95-percent confidence intervals for specific alcohol-related diagnoses, 1979–2005.

[Vertical axes reflect average length of stay in days: scale is not uniform for all graphs]

[Shaded area represents the period before implementation of a new sample design which may affect the trend data. Caution should be taken when assessing differences between the old and new sample design periods.]

Data for figure 9 are presented in Table 3.

 

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