Methods and Limitations
We estimated the number of emergency department (ED) visits with hypoglycemia as first-listed diagnosis among adults aged 18 years or older with diabetes using data from the National Emergency Department Sample (NEDS) of the Agency for Healthcare Research and Quality. NEDS is a nationally representative sample of U.S. community hospital-based EDs and the largest all-payer ED database in the United States, containing ~25–30 million records annually. NEDS collects information on geographic, hospital, and patient characteristics as well as the nature of visits derived from State Emergency Department Databases for those "treat and release" ED visits and from State Inpatient Databases for those admitted to hospitals from EDs. Detailed description on the data is available at http://www.hcup-us.ahrq.gov/db/nation/neds/NEDS_Introduction_2009.pdf [PDF–221KB]. 1
Among adult ED visits having diabetes (ICD-9-CM code 250) as secondary diagnosis, visits with hypoglycemia as first-listed diagnosis were identified using a validated algorithm. 2,3 This algorithm classified ED visits as hypoglycemia cases if they had any of following ICD-9-CM codes: 251.0, 251.1, 251.2, 962.3. Also visits were classified as hypoglycemia cases if they had code 250.8 but without any of the following codes: 259.8, 272.7, 681, 682, 686.9, 707.1, 707.8, 707.9, 709.3, 730.0, 730.1, 730.2, and 731.8. ED visit rates were calculated using two population denominators: estimates of the adult population aged 18 years or older with diagnosed diabetes from the National Health Interview Survey(http://www.cdc.gov/nchs/nhis.htm),4 and estimates of the general population aged 18 years or older from the Census. Rates were age-adjusted on the basis of the 2000 U.S. Standard Population using age groups 18–44 years, 45–64 years, 65–74 years, and 75 years or older.
Because NEDS samples ED visits instead of individual persons, ED visit rates may not necessarily reflect rates per person; that is, persons who had ED visits more than once in a year may be counted more than once. No information on patient’s race/ethnicity, type of diabetes, and insulin usage is available from NEDS.
- Agency for Healthcare Research and Quality. Healthcare Cost and Utilization Project. Introduction to the HCUP Nationwide Emergency Department Sample (NEDS) 2009. Available at http://www.hcup-us.ahrq.gov/db/nation/neds/NEDS_Introduction_2009.pdf [PDF–221KB].
- Ginde A, Blanc P, Lieberman R, Camargo C. Validation of ICD-9-CM coding algorithm for improved identification of hypoglycemia visits. BMC Endocrine Disord. 2008; 8:4.
- Johnson ES, Koepsell TD, Reiber G, Stergachis A, Platt R. Increasing incidence of serious hypoglycemia in insulin users. J Clin Epidemiol. 2002;55:253-259.
- CDC. National Center for Health Statistics. National Health Interview Survey. Available at http://www.cdc.gov/nchs/nhis.htm.