THE MEDITERRANEAN OSTEOPOROSIS STUDY (MEDOS) - THEORETICAL AND PRACTICAL ISSUES OF A MAJOR INTERNATIONAL PROJECT ON HIP FRACTURE EPIDEMIOLOGY

The Mediterranean Osteoporosis Study (MEDOS), a multicentre study on i ncidence, risk factors, and means of prevention of hip fracture in the Mediterranean region, started in 1986 and involved 14 centres, in Por tugal, Spain, France, Italy, Greece, and Turkey. The project comprised three parts: a) a collection of existing register data on hip fractur e occurrence from the 31 European ministries of health; b) a study of hip fracture incidence in the defined areas of the participating centr es in the Mediterranean countries in age groups above 50 years; c) a c ase-control study comparing 8,185 individuals (2,816 cases and 5,369 c ontrols; two controls per case). The structure of the project and its development is described. Methodological issues involving questions of reliability and validity are discussed. A number of measures were tak en in order to obtain a high quality study, e.g., retranslations of th e questionnaire of the case-control study, a separate reliability stud y of the interviewers' performance and uniformity, and a systematic tr acing and estimation of the impact of errors in the data processing pr ocedure. The complexity of the management process and the importance o f effective communication on methodological issues are underlined.