Lessons learned: Challenges faced in the recruitment process for the cluster-randomized nursing home study HIOPP-3 iTBX

Introduction: The cluster-randomized multicenter HIOPP-3 iTBX study ('General Practitioners' Initiative to optimize Medication safety for Nursing Home Residents - using an interprofessional toolbox') aims to improve medication safety in nursing home residents through a complex interprofessional interven-tion focusing on neuroleptics and potentially inadequate medications. A stepwise recruitment process was used for all study participants (nursing homes, general practitioners, pharmacists, nursing home residents). The aim of this article is to describe the underlying recruitment strategy, the results of the recruitment and the measures undertaken to recruit the necessary number of participants. Methods: The recruitment strategy and the response rates of nursing homes, general practitioners, pharmacists and nursing home residents are described. Measures to improve recruitment at the study sites and reasons for refusal to participate were documented. Results: The response rate in nursing homes was 8.4 % (n = 44). Of the pharmacists contacted by these nursing homes 70.3 % (n = 52) participated, and 43.5 % (n = 91) of all contacted general practitioners. Twenty-three (33.0 %) nursing homes had to be excluded from the study because no interprofessional team could be formed. Of all nursing home residents under the care of the participating general practitioners 862 (43,5%) persons and/or their caregivers gave consent to participate in the study. The recruitment for the study took 14 months. In the course of recruitment, recruitment strategies had to be adapted to local circumstances at the study sites. Reasons for non-participation varied between the different groups. Discussion and conclusion: The main challenge in the HIOPP-3 iTBX study was to form interprofessional teams in each cluster. A stepwise, partly dependent recruitment process in a large group of potential participants presents organizational challenges that should be taken into account while planning the study. In order to reach the calculated sample size in the HIOPP-3 iTBX study, a pragmatic and flexible approach, adapted to local circumstances, was required. Further studies may benefit from the experiences made in the HIOPP-3 iTBX study.