Population-based studies on the effect of statin adherence on cardiovascular morbidity in primary prevention of cardiovascular disease that have adjusted for time-dependent confounding
| Country, design, study population | Max follow-up (years) | Exposure definition | Exposure classification | Time-dependent confounders | Outcome | Crude effect estimate (95% CI) | Adjusted effect estimate (95% CI) |
|---|---|---|---|---|---|---|---|
| Canada2 (n=12 180), nested case–control, 50–64 years, 65% ♀ | 3.5 | PDC from statin initiation to time of outcome | ≥90% <90% | Cardiac comorbidities measured during the follow-up | Non-fatal CHD after 1st year of follow-up | RR 0.84 (not reported) 1.00 | RR 0.81 (0.67 to 0.97) 1.00 |
| Canada3 (n=147 601), nested case–control, 45–85 years, 63% ♀ | 6.5 | MPR from statin initiation to time of outcome | ≥80% 60–79% 40–59% 20–39% <20% | Cardiac and non-cardiac comorbidities and medication use measured during the follow-up | Non-fatal CHD or all-cause death after 1st year of follow-up | RR 0.90 (0.85 to 0.96) 0.92 (0.85 to 1.00) 0.94 (0.86 to 1.02) 0.95 (0.87 to 1.04) 1.00 | RR 0.82 (0.77 to 0.87) 0.85 (0.78 to 0.92) 0.87 (0.80 to 1.00) 0.91 (0.84 to 1.01) 1.00 |
| Canada4 (n=41 140), nested case–control, 45–85 years, 63% ♀ | 6.5 | MPR from statin initiation to time of outcome | ≥80% 60–79% 40–59% 20–39% <20% | Cardiac and non-cardiac comorbidities measured during the follow-up | Non-fatal cerebrovascular disease after 1st year of follow-up | RR 0.83 (0.74 to 0.93) 0.93 (0.80 to 1,07) 0.90 (0.76 to 1.06) 1.01 (0.86 to 1.19) 1.00 | RR 0.74 (0.65 to 0.84) 0.82 (0.71 to 0.96) 0.83 (0.70 to 0.98) 0.97 (0.83 to 1.15) 1.00 |
| Italy5 (n=90 832), cohort, ≥18 years (mean 62 years), 59% ♀ | 6 | PDC from statin initiation to time of each outcome | >75% 51–75% 26–50% ≤25% | Concomitant cardiac medication use, and switching of statins measured during the follow-up | Non-fatal CHD after 1st year of follow-up | HR 0.97 (0.85 to 1.12) 0.90 (0.79 to 1.04) 0.86 (0.75 to 0.99) 1.00 | HR 0.81 (0.71 to 0.94) 0.82 (0.71 to 0.95) 0.85 (0.72 to 0.98) 1.00 |
| Israel6 (n=171 535), cohort, 45–75 years, 58% ♀ | 12 | MPR from statin initiation to time of outcome | ≥80% 60–79% 40–59% 20–39% <20% | Efficacy of statin therapy measured during the follow-up | Non-fatal CHD or stroke after 1st year of follow-up | Not reported | HR 0.64 (0.60 to 0.67) 0.63 (0.59 to 0.67) 0.71 (0.67 to 0.75) 0.90 (0.85 to 0.96) 1.00 |
CHD, coronary heart disease; MPR, medication possession ratio; PDC, proportion of days covered; RR, rate ratio.