Predictors of ceasing or reducing statin medication following a large increase in the consumer copayment for medications: a retrospective observational study

Abstract

Objectives:Previous Australian research has shown that following the 21% increase in patient copayments for medications on the Pharmaceutical Benefits Scheme (PBS) in 2005, the use of lipid-lowering therapy declined by 5%. This study aimed to determine the demographic and clinical characteristics of individuals who continued, reduced or ceased their use of statin medication in 2005. Study type: Retrospective observational study using routinely collected administrative data. Method: We used pharmaceutical claims, hospital separations and mortality records from 2000 to 2005 for the Western Australian population. The cohort comprised stable users of statin medication in 2004. Based on changes in statin use between 2004 and 2005, we identified individuals who: 1) continued using statins; 2) reduced their use by ≥20%; or 3) ceased therapy for at least the first 6 months in 2005. Multivariate logistic regression models were used to determine whether the demographic and clinical characteristics of the three groups differed. Results: There were 205 924 statin users identified in Western Australia as of December 2004. After the January 2005 Pharmaceutical Benefits Scheme (PBS) copayment increase, 3.2% of users ceased their regular statin therapy, 12.9% reduced statin use and 83.9% continued statin use. This represented a 2.1% increase in statin users reducing or ceasing therapy compared to 2004. Predictors of cessation and reduction of statin therapy included younger age, greater socio-economic disadvantage, residing in very remote areas, having general beneficiary status, being a new statin user, having no prior history of ischaemic heart disease, having no prior history of a coronary artery revascularisation procedure, taking no other cardiovascular medication or diabetic medication, taking an increased number of medications, and having a lower level of adherence to statin medication in 2004. Conclusion: Compared to 2004, an additional 2.1% of statin users reduced or discontinued medication use in 2005, which may be attributed to an increase in the medication copayment. Individuals with general beneficiary status, and younger and healthier people were at particular risk of cessation or reduction in statin use in 2005.