Patient compliance is crucial for the effectiveness of preventive medication. The aim of the study was to investigate changes in serum cholesterol levels and the use of cholesterol lowering drugs one year after the end of the Scandinavian Simvastatin Survival Study (4S), a randomized secondary prevention study of coronary heart disease with simvastatin and placebo.
A questionnaire asking the current use of cholesterol lowering drugs, most recent serum cholesterol value and attitudes towards cholesterol lowering was sent to 785 surviving 4S participants in four 4S centres in Finland. The response rate was 94%. The current use of cholesterol lowering drugs and the reported mean serum cholesterol values were similar to the original simvastatin and placebo groups. In all, 74% (n=546) reported that they had used cholesterol lowering drugs after the study, and 63% (n=467) were currently using them, mostly simvastatin (96%) with an average dose of 14 (SD 5) mg . day−1 Cholesterol lowering was considered to be ‘very important’ by 53% and ‘important’ by 37% of the respondents. The most frequent reasons for discontinuation were ‘drug costs’ (38%) and ‘normal cholesterol values’ (30%). The reported mean serum cholesterol levels were 5·1 (SD 1·0) and 5·7 (SD 1·1) mmol −1 in the current cholesterol lowering drug users and non-users, respectively (P<0·0001). The in-trial treatment goal of serum cholesterol (≤ 5·2 mmol −1) was not met in 38% of the users and in 68% of the non-users of cholesterol lowering drugs.
One year post-trial the original simvastatin and placebo groups of the 4S had become similar with regard to the use of cholesterol lowering drugs and serum cholesterol levels. The adherence to medication, however, still remained relatively high, but there was a shift toward lower doses, and consequently toward higher post-trial serum cholesterol levels.