Objectives: To compare lipid profiles in patients with rheumatoid arthritis (RA) and in non-RA subjects during the 5 years before and 5 years after the RA incidence/index date.
Methods: Lipid measures were abstracted in a population-based incident cohort of patients with RA (1987 American College of Rheumatology criteria) first diagnosed between 1 January 1988 and 1 January 2008 and in non-RA subjects. Random-effects models adjusting for age, sex and calendar year were used to examine trends in lipid profiles, accounting for multiple measurements for each subject.
Results: The study population included a cohort of 577 patients with RA (a total of 3088 lipid measurements) and 540 non-RA subjects (a total of 3048 lipid measurements). There were significant decreases in total (TC) and low-density lipoprotein cholesterol (LDL) levels in the RA cohort during the 5 years before RA, compared with the non-RA cohort (p<0.001). Decreases of 0.58 mmol/l for TC and 0.61 mmol/l for LDL were noted in RA compared with decreases of 0.09 mmol/l for TC and 0.22 mmol/l for LDL in the non-RA cohort. Trends in other lipid measures (triglycerides (TGs) and high-density lipoprotein cholesterol (HDL)) were similar in RA and non-RA cohorts during the 5 years before and 5 years after the RA incidence/index date. During the 5 years before the RA incidence/index date, the proportion of patients with RA with elevated TC or LDL measures, but not with abnormal HDL and TG measures, significantly decreased compared with non-RA subjects. Lipid-lowering drugs (statins in particular) were less often prescribed to patients with RA than to non-RA subjects (34% vs 41%; p=0.02).
Conclusion: TC and LDL levels and the prevalence of abnormal TC or LDL measures decreased significantly during the 5 years before the RA incidence/index date in patients with RA as compared with the non-RA cohort. These trends in lipid profile in RA are unlikely to be solely due to lipid-lowering treatment.