Payne, R. A., Blair, P. S., Caddick, B., Chew-Graham, C. A., Dreischulte, T., Duncan, L. J., …McCahon, D. (in press). Improving Medicines use in People with Polypharmacy in Primary Care (IMPPP): Protocol for a multicentre cluster randomised trial comparing a complex intervention for medication optimization against usual care. NIHR open research, 2, 54. https://doi.org/10.3310/nihropenres.13285.1