Longitudinal cholesterol trends across socioeconomic groups in Norway: the influence of lipid-lowering drugs in the population-based Tromsø Study 1994–2016

Abstract

Objectives There is limited evidence regarding the impact of lipid-lowering drugs (LLDs) on the socioeconomic gradient in a longitudinal perspective. The study investigates the longitudinal socioeconomic gradient in total cholesterol levels and whether this is affected by the use of LLDs.<p> <p>Design Population-based cohort study. <p>Setting Sample from adult inhabitants of Tromsø municipality, Norway, who participated in the Tromsø Study (1994–2016). <p>Participants 17 550 participants of the population-based Tromsø Study in 1994–1995 who were non-users of LLD, aged 25–78 years at baseline and who attended one or more of three subsequent surveys in 2001, 2007–2008 and 2015–2016 were included in the study. <p>Outcome measure Socioeconomic gradient in total cholesterol levels was compared among participants treated and not treated with LLDs during the observation period. <p>Results The total cholesterol levels across all educational groups increased from 1994–1995 to 2015–2016 among untreated women (+0.33 mmol/L to +0.48mmol/L), except for those with primary education (−0.12mmol/L). Total cholesterol levels decreased among untreated men (−0.40 mmol/L to −0.06mmol/L, from lowest education to highest education), treated women (−1.88 mmol/L to −1.35mmol/L) and men (−2.21 mmol/L to −1.84mmol/L) across all educational groups. At baseline, we observed a significant inverse association between education and total cholesterol levels among non-users of LLDs. There was no clear educational gradient in total cholesterol levels among users of LLDs. <p>Conclusions Users of LLDs experienced a more substantial decrease in total cholesterol levels over time compared with non-users. The educational gradient in total cholesterol levels observed among non-users of LLD was not apparent among users.