Search

Background Both the incidence of myocardial infarction (MI) and short-term case fatality have declined in the UK. However, little is known about trends in longer-term survival following an MI. The aim of the study was to investigate trends in longer-term survival, alongside trends in medication prescribing in primary care. Methods Data came from 218 general practices contributing to the Health Improvement Network, a UK-wide primary care database. 3-year survival and medication use were determined for 6586 men and 3766 women who had an MI between 1991 and 2002 and had already survived 3 months. Results Adjusting for age and gender, the 3-year post- MI case-fatality rate among 3-month survivors fell by 28% (95% CI 13 to 40), from 83 deaths per 1000 person-years for MI occurring in 1991-2 to 61 deaths per 1000 person-years for MI in 2001-2. Relative declines in the case-fatality rate of 37% (20 to 50) and 14% (-11 to 34) were observed for men and women, respectively (p=0.06 for interaction). Prescribing in the 3 months following the MI of lipid-regulating drugs increased from 3% of patients in 1991 to 79% in 2002, prescribing of beta-blockers increased from 26% to 68%, prescribing of ACE inhibitors increased from 11% to 71% and prescribing of anti-platelet medication increased from 46% to 86%. Conclusion There has been a moderate improvement in longer-term survival following an MI, distinct from improvements in short-term survival, although men may have benefited more than women. Increased medication prescribing in primary care may be a contributing factor. [ABSTRACT FROM AUTHOR]

Objective To compare ordinary least squares (OLS) and instrumental variable (IV) estimates of the effects of COX-2 selective inhibitor non-steroidal anti-inflammatory drugs (COX-2s) relative to non-selective NSAIDs (non-selectives) on incidence of gastrointestinal (GI) bleeding, and acute myocardial infarction (MI). We test the validity of the IV estimates, and compare to estimates from randomised controlled trials (RCTs). Design Cohort study using administration data. Setting Primary care. Participants 93 562 patients aged over 65 years attending one of 104 general practices (GP) in the UK. Main outcomes GI bleeding and acute MI. Methods We use data from the UK general practice research database. Our outcomes are incident gastrointestinal bleeding and myocardial infarctions within 60, 120, 180 and 360 days of the first prescription. We estimate risk differences in outcomes using OLS and IVs, using physician prior prescribing as an IV, and compare them to RCT estimates. Results The OLS estimates suggested COX-2s were positively associated with GI bleeds, and were negatively associated with MI. Adjusted OLS estimates were attenuated. In contrast our IV estimates imply –0.43(–1.54,0.68) fewer GI bleeds per 100 people treated with COX-2s after 180 days. The IV estimates provide little evidence, −0.55(−1.2, 1.5), of a difference in MI between treatments. These are comparable to previously published IV estimates and RCT evidence. Conclusions Deriving causal treatment effects using observational health data has proven to be problematic. We demonstrate that in contrast to IV based estimates, conventional OLS methods fail to estimate casual effects as indicated by RCTs. [ABSTRACT FROM PUBLISHER]