title: Determining exposure underreporting in pharmacoepidemiologic case-control studies: methods and example.
abstract: Many pharmacoepidemiologic case-control studies have to rely on what their subjects relate about the drugs to which they have been exposed and the durations of exposure. There is often good reason to suppose that not all exposures are actually reported and to suspect reporting rates may differ between cases and controls. We introduce two procedures designed to determine the extent of underreporting of exposures. These procedures make use of data from the case-control study itself, as well as sales, demographic and market research data for a reference population to which study subjects belong. We apply these procedures to data from the International Primary Pulmonary Hypertension Study (IPPHS) linking anorexigens with PPH. We show that exposures to the anorectic agent dexfenfluramine beginning in or before 1989 were highly significantly underrepresented in the data for IPPHS controls, relative to exposures beginning after 1989 (P<0.01); there is no corresponding evidence for relative underrepresentation of early exposure for IPPHS cases. However, data on control exposures from 1990 to 1992 are consistent with the hypothesis that these exposures were not underreported to the IPPHS. Subject to certain key modeling assumptions and the availability of some supplemental data, it is possible to investigate the extent of underreporting of exposure in a pharmacoepidemiologic case-control study and in particular to determine if study results are likely to have been affected by recall bias.
authors.affiliation: Dipartimento di Economia Politica, Università degli Studi di Modena, Italy.
authors.forename: D A
authors.initials: DA
authors.lastname: Lane
authors.forename: M S
authors.initials: MS
authors.lastname: Kramer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001067:Appetite Depressants / Q000009:adverse effects*; D001530:Belgium / Q000453:epidemiology; D002648:Child; D020372:Dexfenfluramine / Q000009:adverse effects*; D011307:Drug Prescriptions / Q000191:economics / Q000706:statistics & numerical data; D004363:Drug Utilization / Q000191:economics / Q000706:statistics & numerical data; D004335:Drug and Narcotic Control / Q000191:economics / Q000331:legislation & jurisprudence / Q000706:statistics & numerical data; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D006976:Hypertension, Pulmonary / Q000139:chemically induced / Q000191:economics / Q000453:epidemiology*; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D017891:Pharmacoepidemiology / Q000379:methods*; D012189:Retrospective Studies; D017366:Serotonin Receptor Agonists / Q000009:adverse effects*
chemical_list: D001067:Appetite Depressants; D017366:Serotonin Receptor Agonists; D020372:Dexfenfluramine