Pharm World Sci 2002 Oct;24(5):177-81 Measuring the impact of medicines information services on patient care: methodological considerations. Spinewine A, Dean B. Universite Catholique de Louvain, Brussels, Belgium. anne.spinewine@facm.ucl.ac.be INTRODUCTION: Medicines information services (MISs) aim to promote the safe, effective and economic use of medicines. Results from published studies suggest that they provide effective information, which in many cases results in improved patient outcome. However, there are several methodological issues that are important in the interpretation of such studies. AIM: To address methodological issues in the evaluation of MISs. OBJECTIVES: To carry out a critical appraisal of papers assessing the impact on patient outcome of passive information given to health care professionals, to identify the key methodological issues and to make recommendations for future research in Europe. METHODS: Literature search to identify relevant papers meeting the inclusion criteria, critical evaluation of the methods used. RESULTS: Most studies have been conducted in the United States. Various methodological considerations were identified: study design, sampling, data collection, choice of outcome measures, and validity. The results of each study are interpreted in view of the methods used. In addition, the implications of the methods selected on the validity, reliability and generalisability of the results are discussed. Finally, suggestions for future studies are provided, in order to maximise validity and reliability. PMID: 12426961 [PubMed - in process]