loại bỏ chỉ khi họ có tương quan với biến số đã được đo lường và bao gồm trong các mô hình tính toán phân tích biến Instrumental là một phương pháp kinh tế lượng được sử dụng để loại bỏ các tác động của thiên vị ẩn trong quan sát , 72 biến Instrumental liên quan chặt chẽ với điều trị | 12 Research Methods for Pharmacoepidemiology Studies 213 removed only if they are correlated with covariates already measured and included in the model to compute the Instrumental variable analysis is an econometric method used to remove the effects of hidden bias in observational 72 Instrumental variables are highly correlated with treatment and they do not independently affect the outcome. Therefore they are not associated with patient health status. Instrumental variable analysis compared groups of patients that differ in likelihood of receiving a Summary In pharmacoepidemiology research as in for traditional research the selection of an appropriate study design requires the consideration of various factors such as the frequency of the exposure and outcome and the population under study. Investigators frequently need to weigh the choice of a study design with the quality of information collected along with its associated costs. In fact new pharmacoepi-demiologic designs are being developed to improve study efficiency. Pharmacoepidemiology is not a new discipline but it is currently recognized as one of the most challenging areas in research and many techniques and methods are being tested to confront those challenges. Pharmacovigilance see Chapter 5 as a part of pharmacoepidemiology is of great interest for decision makers researchers providers manufacturers and the public because of concerns about drug safety. Therefore we should expect in the future the development of new methods to assess the risk benefit ratios of medications. References 1. Strom B Kimmel S. Textbook of Pharmacoepidemiology. Hoboken NJ Wiley 2006. 2. Miller JL. Troglitazone withdrawn from market. Am J Health Syst Pharm. May 1 2000 57 9 834. 3. Gale EA. Lessons from the glitazones a story of drug development. Lancet. June 9 2001 357 9271 1870-1875. 4. Scheen AJ. Thiazolidinediones and liver toxicity. Diabetes Metab. June 2001 27 3 305-313. 5. Glessner MR Heller
