Intervention delivery
Almost all the participants at intervention sites received the booklet (98.5%) and 91.7% received all three planned follow-up contacts, with most (79.0%) received in the protocolised format (week 1 by telephone, weeks 4 and 12 as preferred by participants). Given the high level of fidelity to the intervention, numbers deviating from protocolised follow-up were small and thus the planned per protocol analyses were underpowered, although findings were consistent with a greater change in IPSS at 12 months in the intervention arm (supplementary table S1). As only nine participants in the intervention arm were deemed to have been non-adherent, the planned complier average causal analysis was not performed.