Lipid monitoring in a community cohort of people taking statins: who is tested and is testing associated with subsequent alteration in therapy?

AIM To describe patterns of community lipid testing and subsequent therapeutic alteration in a cohort of patients taking statins. METHOD We conducted a population-based cohort study. Our cohort comprised all people enrolled with a general practice in the Pegasus Health primary care network in Canterbury, New Zealand between 1 January 2016 and 31 December 2017 who were dispensed a statin between 1 January 2016 and 30 June 2016. We defined two six-month study periods: a baseline period (1 January to 30 June 2016) and a follow-up period (1 July to 31 December 2017). We identified statin dispensings for all people in our cohort in both study periods, and identified instances of lipid testing in the 12 months following each person's most recent baseline period dispensing. We examined the effect of gender, ethnicity and socioeconomic deprivation on the likelihood of lipid testing; and compared frequency of alteration of statin dose or type among tested and non-tested people. RESULTS Data were available for analysis for 32,943 individuals who were dispensed a statin in the baseline period. Lipid testing was performed in 16,199 (49.2%) of individuals. Women were less likely to have been tested than men (OR 0.87, 95% CI 0.83-0.91). Compared to those with European ethnicity, testing was more likely for Māori (OR 1.20, 95% CI 1.07-1.34), Pacific (OR 1.22, 95% CI 1.03-1.44) and Asian (OR 1.41, 95% CI 1.25-1.59) individuals. Socioeconomic deprivation was associated with reduced testing (OR 0.80, 95% CI 0.74-0.87). Dose or type of statin dispensed was altered between baseline and follow-up study periods in 3,762 (23.2%) of those who were tested, and in 3,122 (18.6%) of those who were not tested (OR 1.32, 95% CI 1.25-1.39). CONCLUSION Almost half (49.1%) of patients had a lipid test within 12 months of baseline period statin dispensing. Lipid testing was more likely for Māori, Pacific and Asian patients than for European patients. Testing was less likely for women and for those with greater socioeconomic deprivation. Subsequent statin therapy alteration was slightly more likely for those who had been tested than for those who had not.