Does the type of pharmacy used influence medication adherence? A retrospective observational study in Aotearoa, New Zealand.

Background: Community pharmacies in New Zealand have varying ownership and operational structures. Unlike independent pharmacies, corporate and hybrid pharmacies do not charge prescription copayments.

Objectives: This research aimed to determine whether people receiving free prescriptions from corporate and hybrid pharmacies (via copayment waiver) have greater medication adherence than the users of independent pharmacies.

Methods: A nationwide, retrospective, observational study linked 1 year of dispensing data (1/05/2022 to 30/04/2023) from the Pharmaceutical Collection to patient enrollment data using a National Health Index number to identify demographics of different pharmacy-type users. People were assigned to a particular type of pharmacy if they collected at least 70% of their prescriptions from there; if they did not meet this threshold, they were defined as mixed users. People were classified as adherent if dispensing data showed they collected their supply of medication to cover at least 80% of the study period.

Results: The sample captured 218,080 people taking at least 1 diabetes medication, with a total of 360,079 unique medications being included in the analysis. The majority, 156,893, used independent pharmacies. The type of pharmacy used was shown to be a significant predictor of adherence. Corporate and hybrid pharmacy users were 0.90 (95% CI 0.88 to 0.93) and 0.93 (95% CI 0.90 to 0.96) times as likely be adherent than the users of independent pharmacies. Mail order pharmacy users were the most likely to be adherent, whereas mixed pharmacy users were the least likely to be adherent.

Conclusions: Our findings suggest that prescription copayments provided by corporate and hybrid pharmacies are not the most significant barrier to medication adherence. Further research may identify more efficient ways of improving medication adherence than removing prescription copayments for all.