Consequences of cost barriers to prescriptions: cohort study in Aotearoa New Zealand.

Aims: A NZ$5 co-payment prescription charge was removed in July 2023 but may be reinstated. Here we quantify the health impact and cost of not being able to afford this charge.

Methods: We linked New Zealand Health Surveys (2013/2014-2018/2019) to hospitalisation data using data available in Integrated Data Infrastructure (IDI). Cox proportional-hazards models compared time to hospitalisation between those who had faced a cost barrier to collecting a prescription and those who had not.

Results: Of the 81,626 total survey respondents, 72,243 were available for analysis in IDI. A further 516 were excluded to give an analysis dataset of 71,502. Of these, 5,889 (8.2%) reported not collecting a prescription due to cost in the previous year. Among people who faced a cost barrier, 60.0% (95% confidence interval [CI] 58.7-61.2%) were admitted to hospital during the study period, compared to 43.9% (95% CI 43.6-44.3%) of those who did not. Having adjusted for socio-demographic variables, people who faced a cost barrier were 34% (hazard ratio 1.34; 95% CI 1.29-1.39) more likely to be admitted to hospital than those who did not. Annual avoidable hospitalisation costs-were prescription co-payments to remain free-are estimated at $32.4 million per year based on the assumption of a causal relationship between unmet need for prescription medicines and subsequent hospitalisation.

Conclusions: The revenue to the health system from co-payments may be offset by the costs associated with avoidable hospitalisations.