Abstract
Background: In New Zealand, a setting in which national guidelines recommend statins for all patients with coronary heart disease (CHD) and cost barriers are low, patterns of use of these drugs are unknown. We investigated dispensing rates after hospital discharge for acute CHD event.
Design: Retrospective cohort study.
Methods: Drug dispensing, hospital diagnosis, and mortality records were linked by unique identifier for all New Zealanders aged 35-84 years after discharge following acute CHD event in 2007. We defined the statin dispensing ratio (SDR) as the proportion of days that 15,506 patients aged 35-84 years were dispensed such agents during the 12 months post discharge. An SDR >= 0.8 (80% or more days covered) was considered optimal.
Results: Overall, 59% of the cohort had an SDR >= 0.8. Of patients dispensed statins in the 3 months before admission (n=5506), almost all (99%; 5466) continued treatment during follow up and 82% had an SDR >= 0.8. In contrast, for patients not dispensed statins before admission (n=8014), only two-thirds started statins during follow up and only 44% had an SDR >= 0.8. Of all patients with low statin dispensing (SDR <0.8), about one-quarter were not dispensed any lipid-lowering drugs, one-quarter received alternative lipid-lowering drugs, one-quarter stopped statins, and the remaining quarter were intermittent statin users.
Conclusion: In a setting with few barriers to statin treatment, about 40% of patients had suboptimal statin dispensing during the year after hospital treatment for CHD. This study has identified four significant categories of suboptimal adherence that could inform quality improvement programmes.