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Background: There is conflicting evidence on the reduction of cardiovascular risk in diabetic patients treated with oral antidiabetic agents., Objectives: To compare the risk of myocardial infarction (MI) and coronary revascularization (CR) in type 2 diabetic patients treated with rosiglitazone, metformin, or sulfonylurea., Methods: Using data from a large US insurer, we created propensity-matched cohorts. We identified hospitalizations for MI or CR. We calculated incidence rates and 95% confidence intervals for the outcomes and estimated risks from Cox proportional hazards models., Results: We identified 26,931 initiators of monotherapy, 4,086 initiators of dual-therapy, and 2,346 initiators of combination with insulin therapy. There was no difference between the risk of the composite outcome with rosiglitazone monotherapy compared to metformin monotherapy (HR 1.07, 95% CI: 0.85, 1.34), and similarly with rosiglitazone monotherapy compared to sulfonylurea monotherapy (HR 0.82, 95% CI: 0.67, 1.02). There was no difference in the risk of outcome with rosiglitazone in combination with insulin therapy compared to other oral antidiabetic agents in combination with insulin (HR 0.88, 95% CI: 0.59, 1.32). Overall, there was little difference in the risk of the composite outcome or of the individual outcomes of MI and CR comparing rosiglitazone therapies to non-rosiglitazone therapies (HR for composite outcome 0.93, 95% CI: 0.80, 1.10)., Conclusions: The results from the monotherapy and the dual-therapy comparisons, though not individually significant, are consistent in suggesting that the risk of cardiovascular outcome events in patients using rosiglitazone may lie between the risks associated with sulfonylureas (higher incidence) and metformin (lower incidence).

Objective: To estimate the incidence of venous thromboembolism, acute myocardial infarction, and ischemic stroke among transdermal contraceptive system users compared with users of norgestimate-containing oral contraceptives with 35 mcg ethinyl estradiol., Methods: We began with insurance claims data from UnitedHealthcare. We identified women exposed to the transdermal contraceptive system or norgestimate-containing oral contraceptives from April 2002 through December 2004. Outcomes were confirmed from medical records. We calculated incidence rates and age-adjusted incidence rate ratios. In a nested case-control analysis, we investigated and controlled for confounding., Results: There were 49,048 woman-years of transdermal contraceptive system exposure and 202,344 woman-years of norgestimate-containing oral contraceptives exposure. There was a more than two-fold increase in the venous thromboembolism rate (incidence rate ratio 2.2, 95% confidence interval [CI] 1.3-3.8) among transdermal contraceptive system users (20 cases, 40.8 per 100,000 woman-years) compared with norgestimate-containing oral contraceptives users (37 cases, 18.3 per 100,000 woman-years). Acute myocardial infarction occurred in three transdermal contraceptive system users compared with seven among norgestimate-containing oral contraceptives users (incidence rate ratio 1.8, 95% CI 0.5-6.8). No strokes occurred among transdermal contraceptive system users, whereas 10 occurred among norgestimate-containing oral contraceptives users. In the nested case-control analysis, after exclusions for high-risk factors, the odds ratio for venous thromboembolism was 2.4 (95% CI 1.1-5.5)., Conclusion: There was a more than two-fold increase in the risk of venous thromboembolism associated with use of the transdermal contraceptive system. Acute myocardial infarction and stroke occurred too rarely to ascertain precise risk estimates., Level of Evidence: II.

Background: Confounding by indication is a common problem in pharmacoepidemiology, where predictors of treatment also have prognostic value for the outcome of interest. The tools available to the epidemiologist that can be used to mitigate the effects of confounding by indication often have limits with respect to the number of variables that can be simultaneously incorporated as components of the confounding. This constraint becomes particularly apparent in the context of a rich data source (such as administrative claims data), applied to the study of an outcome that occurs infrequently. In such settings, there will typically be many more variables available for control as potential confounders than traditional epidemiologic techniques will allow., Methods: One tool that can indirectly permit control of a large number of variables is the propensity score approach. This paper illustrates the application of the propensity score to a study conducted in an administrative database, and raises critical issues to be addressed in such an analysis. In this example, the effect of statin therapy on the occurrence of myocardial infarction was examined, and numerous potential confounders of this association were adjusted simultaneously using a propensity score to form matched cohorts of statin initiators and non-initiators., Results: The incidence of myocardial infarction observed in the statin treated cohort was lower than the incidence in the untreated cohort, and the magnitude of this effect was consistent with results from randomized placebo controlled clinical trials of statin therapy., Conclusions: This example illustrates how confounding by indication can be mitigated by the propensity score matching technique. Concerns remain over the generalizability of estimates obtained from such a study, and how to know when propensity scores are removing bias, since apparent balance between compared groups on measured variables could leave variables not included in the propensity score unbalanced and lead to confounded effect estimates., (Copyright 2005 John Wiley & Sons, Ltd.)

This investigation quantified the effect of statins on acute myocardial infarction (AMI) in an observational setting where fluvastatin represented most of the statin use. The study applied propensity scores to match statin initiators to statin noninitiators and followed them for the occurrence of AMI. Serum low-density lipoprotein levels were reduced by statin therapy, and there were fewer incidents of AMI in statin initiators than in noninitiators.

Background: There is clear evidence from numerous randomized trials and their meta-analyses that aspirin reduces risks of first myocardial infarction (MI). Recent data also suggest that other nonsteroidal anti-inflammatory drugs (NSAIDs) may interfere with this benefit of aspirin., Methods and Results: We performed subgroup analysis from a 5-year randomized, double-blind, placebo-controlled trial of 325 mg aspirin on alternate days among 22 071 apparently healthy US male physicians with prospective observational data on use of NSAIDs. A total of 378 MIs were confirmed, 139 in the aspirin group and 239 in the placebo group. Aspirin conferred a statistical extreme (P<0.00001) 44% reduction in risk of first MI. Among participants randomized to aspirin, use of NSAIDs on 1 to 59 d/y was not associated with MI (multivariable adjusted relative risk [RR], 1.21; 95% confidence interval [CI], 0.78 to 1.87), whereas the use of NSAIDs on > or =60 d/y was associated with MI (RR, 2.86; 95% CI, 1.25 to 6.56) compared with no use of NSAIDs. In the placebo group, the RRs for MI across the same categories of NSAID use were 1.14 (95% CI, 0.81 to 1.60) and 0.21 (95% CI, 0.03 to 1.48)., Conclusions: These data suggest that regular but not intermittent use of NSAIDs inhibits the clinical benefits of aspirin. Chance, bias, and confounding remain plausible alternative explanations, despite the prospective design and adjustment for covariates. Nonetheless, we believe the most plausible interpretation of the data to be that regular but not intermittent use of NSAIDs inhibits the clinical benefit of aspirin on first MI.

Objective.—To estimate rates of vascular events in relation to dispensing of triptans and ergot alkaloids among migraineurs, and to compare these rates with those of nonmigraineurs. Context. —It has been speculated that the use of triptans or ergot alkaloid drugs might increase risk of ischemic events through vasoconstriction. Design.—A retrospective cohort study of 130,411 migraineurs and 130,411 age-, sex-, and health plan-matched nonmigraineurs who were members of UnitedHealthcare during 1995 through 1999. The data source for this study was Ingenix's research database containing pharmacy and medical claims for UnitedHealthcare members, and the National Death Index. Main Outcome Measures .—Incidence of cardiovascular and cerebrovascular events and mortality. Results.—Migraineurs and nonmigraineurs had identical rates of myocardial infarction: 1.4 per 1000 person-years. Migraineurs were 67% more likely to suffer a stroke than nonmigraineurs (adjusted relative risk [RR] 1.67, 95% confidence interval [CI] 1.31–2.13), and had higher rates of unstable angina and transient ischemic attacks. There was no increase in risk of myocardial infarction with current (adjusted RR 0.80, 95% CI 0.58–1.11) or recent (adjusted RR 1.15, 95% CI 0.71–1.87) triptan use. Neither current (adjusted RR 0.90, 95% CI 0.64–1.26) nor recent (adjusted RR 0.84, 95% CI 0.46–1.55) triptan use was associated with risk of stroke. Current users of ergot alkaloids were somewhat more likely to have a stroke than other migraineurs (adjusted RR 1.49, 95% CI 0.93–2.41), but there was no dose-response relationship. Conclusions.—Use of triptans is not associated with increased risk of any ischemic events, including myocardial infarction and stroke, or mortality. Consistent with previous studies, migraineurs in general have an elevated risk of stroke, but not myocardial infarction, compared with nonmigraineurs. [ABSTRACT FROM AUTHOR]

This article presents a letter to the editor regarding myocardial infarction as reported in the March 5, 1998, issue.

Abstract: Background: The oral contraceptive ethinyl estradiol 0.03 mg/drospirenone 3 mg (EE/DRSP) contains a progestin component that possesses potassium-sparing diuretic activity similar to spironolactone. We sought to determine whether EE/DRSP use might lead to adverse effects possibly attributable to hyperkalemia. Study Design: This was a matched cohort study in which we identified oral contraceptive (OC) initiators between July 2001 and June 2004 within a large, US health plan. We matched EE/DRSP initiators to other OC initiators in a 1:2 ratio on the basis of a prediction model (propensity score) of EE/DRSP initiation that incorporated dozens of characteristics. We identified insurance claims mentioning hyperkalemia, related clinical outcomes (electrolyte disturbances, arrhythmia, syncope, myocardial infarction) and verified the underlying condition through medical record review. Results: There were 22,429 EE/DRSP initiators matched to 44,858 other OC initiators, with an average follow-up of 7.6 months. A composite clinical surrogate hyperkalemia end point occurred with equal frequency in the compared groups [118 cases in EE/DRSP and 260 in comparators; rate ratio (RR) 0.9, 95% confidence interval (CI) 0.7–1.1]. The individual hyperkalemia surrogate end points exhibited similar results. One EE/DRSP initiator and four comparators were diagnosed specifically with hyperkalemia (RR 0.5, 95% CI 0.0–4.9). The results were not different when we accounted for changes in OC use during follow-up. Conclusion: EE/DRSP initiators are no more likely than other OC initiators to experience hyperkalemia or related clinical outcomes which could be caused by hyperkalemia during follow-up. [Copyright &y& Elsevier]