Sample size estimation/Statistical Power
RECRUITMENT, PCP
Power was calculated based on simulations exploring four possible scenarios to consider different time trends of the intervention effect as well as a possible assessment impact in the control group. Assessment impact means that the regular recording of opioid use in the monthly assessments causes self-awareness which leads to behavior modifications [The original protocol planned to enroll 60 PCP clusters with approximately 8 patient participants per PCP cluster for a total of 480 patient participants. The results of the simulations showed power for all 4 scenarios with 60 PCP clusters and 8 patient participants per PCP cluster to be at least 95%. During the trial, patient recruitment challenges led to a re-evaluation of whether sufficient power could be maintained with a reduced sample size, given that the study had been very highly powered. Therefore, we re-ran the power simulations and showed that that the following two conditions were all four scenarios had adequately power (89–99%) for the following two sample sizes: 1) 60 PCP clusters with 5 patients per PCP cluster for a total of 300 patient participants and 2) 50 PCP clusters with 4 patients per PCP cluster for a total of 200 patient participants, with power for all 4 scenarios for both conditions in the range of 89% to 99%.Based on these results and the observation that the study had not yet been able to identify eligible patients for 30–40% of enrolled PCPs, the study was modified to plan for enrollment of approximately 100 PCPs from a total of 5 sites, which should leave approximately 60 PCP clusters with patients enrolled into the study (noting that only 1 site practices in teams). Based on prior studies of general population prevalence of opioid misuse of 3.9–6.6% [