In the National Hospital Ambulatory Medical Care Survey, data are collected on cause of injury at emergency department visits by means of an open-ended item, “Cause of Injury.” This item asks the respondent (typically hospital staff or Census field representatives) to describe the place and events that preceded the injury, poisoning or adverse effect. Verbatim text is coded by NCHS contracted medical coders using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM), Supplementary Classification of External Causes of Injury and Poisoning. Up to three causes may be coded per visit.
FOR SINGLE DATA YEARS: Emergency department visit rates are calculated using the July 1 estimates of the civilian noninstitutionalized population from the Vintage matching the data year for the postcensal period based on the 2000 census. For example, July 1, 2007 civilian noninstitutionalized population estimates from Vintage 2007 are used as the denominator for 2007 rates. Rates for 2010 are also calculated using the July 1 estimates based on the 2000 census.