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Compliance with medication in the Helsinki Heart Study
H Mäenpää1, V Manninen, O P Heinonen
1First Department of Medicine, University of Helsinki, Finland.
Insights
Medication compliance in the Helsinki Heart Study was assessed using capsule counting, urine analysis, and a digoxin marker. Compliance slightly declined over time, with slightly better adherence in the placebo group.
Area of Science:
- Clinical Research
- Pharmacology
- Public Health
Background:
- Medication compliance is critical for clinical trial validity.
- The Helsinki Heart Study evaluated gemfibrozil's efficacy in dyslipidaemic men.
Purpose of the Study:
- To assess medication compliance in the Helsinki Heart Study.
- To compare three methods for estimating compliance: capsule counting, urine gemfibrozil analysis, and a digoxin marker.
Main Methods:
- Employed capsule counting at 3-month intervals.
- Utilized urine gemfibrozil analysis every 6 months.
- Introduced a novel digoxin marker in years 3 and 5.
Main Results:
- Capsule counting: 36-39% took >90% of medication; 5% took ≤50%.
- Urine analysis: 30% of gemfibrozil subjects had >90% positive results; 28% had ≤50% positive.
- Digoxin marker: 42-50% of completers had good results; 12-14% had poor results.
- Compliance showed a slight decline over the study period, confirmed by all methods.
Conclusions:
- Multiple methods provide estimates of medication compliance.
- Compliance slightly decreased during the Helsinki Heart Study.
- Slightly better compliance was observed in the placebo group based on two methods.
Abstract:
Compliance with medication has a decisive influence on the findings in clinical intervention studies, so the reliable estimation of compliance is vital to the success of such research. This report describes the main findings about compliance in the Helsinki Heart Study, a five-year, double-blind, primary prevention trial of gemfibrozil as a lipid-lowering agent compared with placebo, in 4,081 dyslipidaemic middle-aged men. Three estimation methods were employed: capsule counting at every three-month follow-up visit, urine gemfibrozil analysis at six-month intervals, and, a novel technique, a digoxin marker added to both gemfibrozil and placebo capsules at the end of the third and fifth study years. The estimates of compliance for the study population as a whole generated by these three methods are discussed here. The mean daily capsule count showed that 36% of patients on gemfibrozil men and 39% of those on placebo took more than 90% of their capsules, while only 5% of both groups consumed half or less of the prescribed treatment. According to urinary gemfibrozil analysis, 30% of gemfibrozil subjects had more than 90% positive results and 28% had half or fewer positive. Among study completers, there were 42% gemfibrozil subjects and 50% placebo subjects who on both occasions had the good result in the digoxin marker analysis, while 14% of the gemfibrozil men and 12% of the placebo men scored 'poor' in both marker analyses. Capsule counting revealed a slight deterioration in compliance over the trial period, which was confirmed by the other two methods; for example, the proportion of positive results in the semiannual urine gemfibrozil analyses decreased from 76% to 65%. Medication compliance was slightly better in the placebo group according to capsule counting and digoxin marker methods.(ABSTRACT TRUNCATED AT 250 WORDS)