Cost effectiveness of a GP delivered medication review to reduce polypharmacy and potentially inappropriate prescribing in older patients with multimorbidity in Irish primary care: the SPPiRE cluster randomised controlled trial

Background Evidence on the cost effectiveness of deprescribing in multimorbidity is limited. Objective To investigate the cost effectiveness of a general practitioner (GP) delivered, individualised medication review to reduce polypharmacy and potentially inappropriate prescribing in older patients with multimorbidity in Irish primary care. Methods Within trial economic evaluation, from a healthcare perspective and based on a cluster randomised controlled trial with a 6 month follow up and 403 patients (208 Intervention and 195 Control) recruited between April 2017 and December 2019. Intervention GPs used the SPPiRE website which contained educational materials and a template to support a web-based individualised medication review. Control GPs delivered usual care. Incremental costs, quality adjusted life years (QALYs) generated using the EQ-5D-5L instrument, and expected cost effectiveness were estimated using multilevel modelling and multiple imputation techniques. Uncertainty was explored using parametric, deterministic and probabilistic methods. Results On average, the SPPiRE intervention was dominant over usual care, with non-statistically significant mean cost savings of €410 (95% confidence interval (CI): − 2211, 1409) and mean health gains of 0.014 QALYs (95% CI − 0.011, 0.039). At cost effectiveness threshold values of €20,000 and €45,000 per QALY, the probability of SPPiRE being cost effective was 0.993 and 0.988. Results were sensitive to missing data and data collection period. Conclusions The study observed a pattern towards dominance for the SPPiRE intervention, with high expected cost effectiveness. Notably, observed differences in costs and outcomes were consistent with chance, and missing data and related uncertainty was non trivial. The cost effectiveness evidence may be considered promising but equivocal. Trial registration ISRCTN: 12752680, 20th October 2016.