Methods and Limitations
We estimated the number of hospital discharges involving persons with diabetes using data from the National Hospital Discharge Survey (NHDS), National Center for Health Statistics, Centers for Disease Control and Prevention. NHDS collects data on hospital discharges from a sample of short-stay, nonfederal hospitals in the United States. Data collected include information on patients' age, race, sex, and length of stay, and on seven diagnoses (one primary and six secondary diagnoses) and four surgical procedures. Methods used for conducting the survey have been described previously.1,2
Hospital discharges for which diabetes (ICD-9 code 250) was listed as any of seven diagnoses were examined. Rates were calculated using resident population estimates and estimates of the population with diabetes. Rates were adjusted to the 2000 U.S. Standard Population using four age groups (0–44, 45–64, 65–74, 75+).
Hospital discharge rate estimates were age-adjusted using National Center for Health Statistics estimates of the 2000 U.S. population as the standard. Because the estimates were produced prior to the year 2000, a slight difference may occur between crude and age-adjusted rates for 2000.3
Hospitalizations involving persons with diabetes may be underestimated because long-term and federal hospitals are not included in the NHDS sample. Race-specific discharges are particularly underestimated because a substantial proportion of discharges are missing racial classification and missing values for race are not imputed.4
Because NHDS samples hospital discharges and not individual persons, NHDS hospital discharge rates for diabetes-related diseases and procedures may not necessarily reflect rates per person; that is, persons who are hospitalized more than once in a year may be counted more than once.
In 1983, Medicare instituted a prospective payment system that has influenced both hospitalization practices and disease reporting on discharge records.
- Dennison C, Pokras R. Design and operation of the National Hospital Discharge Survey: 1988 redesign. Vital and Health Statistics 2000;1(39).
- Graves EJ. National Hospital Discharge Survey: Annual Summary, 1990. Vital and Health Statistics 1992; 13(112) .
- Klein RJ, Schoenborn CA. Age adjustment using the 2000 projected U.S. population. Healthy People Statistical Notes Vital and Health Statistics 2001; no. 20.
- Kozak LJ. Underreporting of race in the National Hospital Discharge Survey. Advance data from vital and health statistics Vital and Health Statistics 1995; no 265.