J Clln Epkmiol Vol. 45, No. 8, pp. 835-839, 1992 0895-4356/92 S5.00 + 0.00 Printed in Great Britain. All rights reserved Copyright 0 1992 Pergamon Press Ltd EPIDEMIOLOGY OF DIABETES MELLITUS IN SOUTHERN ITALY: A CASE-FINDING METHOD BASED ON DRUG PRESCRIPTIONS OLGA VACCARO,‘* GIUSEPPINA IMPERATORE,’ASSIAMIRA FERRARA,’ RAFFAELE PALOMBINO’ and GABRIELE RICCARDI’ ‘Institute of Internal Medicine and Metabolic Diseases, Second Medical School, University of Naples and *Epidemiology Unit, 22nd Health District of the Campania Region, Italy (Received in revised form 25 February 1992) Abstract-The study evaluates whether data concerning drug prescriptions available from the National Health System (NHS) can be used to provide an estimate of the prevalence and pattern of treatment of diabetes in a well defined health district in southern Italy. In Italy virtually all drug prescriptions are obtained through the NHS. For a period of three consecutive months all prescriptions of insulin, hypoglycemic agents and strips for blood and urine testing were monitored in a well defined area near Naples. 2958 cases were thus identified giving a prevalence of drug treated diabetes mellitus of 2.01%; prevalence was higher in females than in males (2.68 vs 1.35%) and increased with age from 0.05% in the age group below 9 years to 13.67 in the age group over 70 years. This case-finding procedure was validated by cross-check with independent sources of cases. To evaluate the sensitivity of the method a list of 820 “known” cases of drug treated diabetes mellitus was obtained from a random sample of local general practitioners (GPs) and diabetic clinics: 73.5% of these cases were also detected through the analysis of drug prescriptions. To evaluate the probability of misclassification a random subsample of 602 cases identified through prescriptions was submitted to the GPs working in the study area, for 517 the diagnosis of diabetes was confirmed, thus yielding a positive predictive value of 85.9%. After correction for sensitivity and probability of misclassification the prevalence of drug treated diabetes in our population was 2.52%. The pattern of prescriptions in this population is also given. In conclusion, drug prescription monitoring represents a quick and inexpensive method for the identification of pharmacologically treated diabetic patients with a reasonable sensitivity and probability of misclassification. Diabetes Epidemiology Drug prescriptions Screening INTRODUCTION There is little information on the incidence and prevalence of diabetes mellitus in Italy. Studies undertaken in the past suffer from major meth- odological problems and this accounts for the inconsistency of the estimated prevalence ‘All correspondence to be addressed to: Dr 0. Vaccaro, Institute of Internal Medicine and Metabolic Diseases, II Policlinico, Via S. Pansini 5, 80131 Napoli, Italy. among studies [l-3]. Further information is needed in order to evaluate the significance of diabetes as a public health problem in Italy and to allow international comparisons. However, the applicability and justification of some of the traditional screening methods is now open to question. The cost/benefit balance of screening population samples with the object of case finding is not rewarding [4]. Due to the spreading use of computerized systems for the 835