a few months ago a paper in the analysed the incidence of venous thromboembolism before and after the warning from the UK Committee on Security of Medicines about third generation oral contraceptives. in women using third generation oral contraceptives was about twice that in users of preparations made up of levonorgestrel. Moreover fewer cases occurred after the warning than would have been expected if the prescribing of oral contraceptives had not changed. What is remarkable is that these two studies reporting reverse conclusions both used Rabbit polyclonal to ADAP2. the same General Practice Analysis Database.4 How do we describe their discrepant findings? Area of the explanation must lay in the methods used. Farmer et al did not use all the VX-689 information they held about the exposure and risk factors of individuals showing instead a time correlation study.1 Users of any combined oral contraceptive were counted in the same way. As one correspondent observed “Simple analyses have rhetorical power that exceeds their medical merit.”5 Jick et al replicated this approach for the purpose of comparison but also offered cohort and nested case-control analyses.3 These uncovered important confounding factors: the reduction in use of third generation oral contraceptives mainly involved young ladies (who are at low risk of venous thromboembolism) and doctors also tended to avoid prescribing such contraceptives for obese ladies or smokers. The 1st study involved little attempt to control for confounding.1 There was adjustment for age but even this may not have been fully adequate. In calculating the number of instances expected after October 1995 the authors stated that they standardised for age by using the data on overall use from the two periods. A subsequent sentence suggested that this referred to use of any combined oral contraceptive rather than specific types. VX-689 If so there was no allowance for the fact the switching from third generation oral contraceptives to additional formulations was primarily by young women-who were at the lowest risk of venous thromboembolism. Jick et al present several other explanations for his or her different findings.3 Doctors may be tempted to low cost these two studies concluding that they cancel each other out inside a “tit for tat” manner. This would become unwise for only one of them can have the right solution. The elegant design and analysis of the new VX-689 study mean that it could be the most important paper yet published on this vexed subject. As well as answering the previous report it provides vital evidence on several controversial matters-including the improved risk in first time users of oral contraceptives the part of risk factors such as obesity and smoking and the irrelevance of prior switching of oral contraceptive preparations.3 The two groups have been producing conflicting results on this subject for several years 6 7 and Farmer et al have also sought to explain VX-689 the differences.8 Surely it is time for the Medicines Control Agency which now owns the General Practice Study Database to carry out a thorough investigation. The whole stand-off is damaging to the trustworthiness of pharmacoepidemiology in general and the General Practice Research Database in particular. The second option is definitely a research tool of global importance.9 The Boston group and its collaborators have used it in over 100 publications including studies on appetite suppressants and heart valve disorders 10 analgesics and gastrointestinal bleeding 11 and antidepressants and suicide.12 Such study can help lay to rest false alarms about medication safety.13 Additionally it may disclose unexpected great things about medicines like the possibility that statins may decrease the threat of fractures.14 The Medications Control Company is wanting to produce the data source more widely accessible for analysis and research. This seems attractive but it addittionally presents difficult to researchers to become as rigorous as it can be in the utilization they label of it. There’s a additional separate problem elevated by causing the database even more widely available specifically the chance of publication bias. It really is notable a third research on dental contraceptives and thromboembolism using the same data source was conducted with respect to a pharmaceutical firm but it has hardly ever noticed the light of time. Pharmacoepidemiology is a robust tool that may benefit sufferers and the general public wellness but only when it is utilized properly. ? Editorial footnote We do poorly with.