Postmarketing drug surveillance by record linkage in Tayside.

Abstract

The feasibility of conducting postmarketing drug surveillance by record linkage in Tayside was assessed. The key feature of the method was that all hospital discharge data were already computerized by the area health board and accessed through the unique community health number (CHNo) allocated to all Tayside residents. The 12,861 prescriptions for cimetidine dispensed in Tayside over 9 mo. were collected and the CHNo identified for 76%. These corresponded to 3802 individuals and their discharge data, together with those for an equal number of controls matched by age, sex and general practitioner were retrieved from the computer. The expected excess of those diseases for which cimetidine was prescribed (peptic ulcer and esophagitis) was observed. Other drug-disease associations were observed but may have been due to confounding and emphasized the inadequacy of community based controls. The major advantages of record linkage were the low cost of the method and the duration of patient follow up which may have been extended for as many years as required by rerunning the computer programs. To assemble large patient cohorts the study would have to be extended to other area health boards that are currently developing similar computer systems. Record linkage may provide a cost effective method for the follow up of patients to identify serious adverse drug reactions, particularly those that take several years to develop.