Background—Previous research shows that low socioeconomic position (SEP; especially low income) is associated with
statin nonadherence. We investigated the relationship between SEP and statin adherence in a country with universal
coverage using group-based trajectory modeling in addition to the proportion of days covered. 

Methods and Results—Using data from Finnish healthcare registers, we identified 116 846 individuals, aged 45 to 75 years,
who initiated statin therapy for primary prevention of cardiovascular disease. We measured adherence as proportion of days
covered over an 18-month period since initiation and identified different adherence patterns based on monthly adherence
with group-based trajectory modeling. When adjusted for age, marital status, residential area, clinical characteristics,
and copayment, low SEP was associated with statin nonadherence (proportion of days covered <80%) among men (eg,
lowest versus highest income quintile: odds ratio, 1.41; 95% confidence interval, 1.32–1.50; basic versus higher-degree
education: odds ratio, 1.18; 95% confidence interval, 1.13–1.24; unemployment versus employment: odds ratio, 1.17;
95% confidence interval, 1.10–1.25). Among women, the corresponding associations were different (P<0.001 for sex-byincome
quintile, sex-by-education level, and sex-by-labor market status interactions) and mainly nonsignificant. Results
based on adherence trajectories showed that men in low SEP were likely to belong to trajectories presenting a fast decline
in adherence.

Conclusions—Low SEP was associated with overall and rapidly increasing statin nonadherence among men. Conversely,
in women, associations between SEP and nonadherence were weak and inconsistent. Group-based trajectory modeling
provided insight into the dynamics of statin adherence and its association with SEP