Abstract
<title>Abstract</title> <p>Background In primary care trials, variation in adherence under real-world conditions can influence treatment effects and inform implementation. The multicenter PICTURE trial in German primary care evaluated a brief psychological intervention for adult ICU survivors with at least moderate PTSD symptoms. The intervention comprised three structured narrative exposure sessions with the general practitioner, controls received three scheduled GP consultations within routine care. The primary outcome was PTSD symptom severity (PDS-5) at 6 months. Methods Adherence was defined as completion of three GP sessions within 18 weeks in the intervention group and 6 months in the control group. Conditional average treatment effects were estimated, adjusting for covariates potentially relevant to adherence. Group-specific effects were compared and heterogeneity formally tested. Sensitivity analyses included restricted per-protocol and intention-to-treat linear regression models. Results Among 316 participants, the mean baseline PDS-5 score was 30.6. At 6 months, 69.3% of participants were fully adherent, 15.5% partially adherent, and 15.2% dropped out. The overall average treatment effect was − 4.54 (95% CI − 7.63 to − 1.44) at 6 months and − 5.28 (95% CI − 8.88 to − 1.67) at 12 months. Effects were similar among fully adherent participants and partially adherent participants, with no significant heterogeneity between adherence strata. Sensitivity analyses yielded comparable estimates in magnitude and direction. Conclusions The intervention’s effectiveness is robust under real-world implementation variability in terms of frequency and timing. Consistent effects across adherence strata and analytic approaches support the robustness of this brief primary care psychological intervention for post-ICU PTSD symptoms under routine care conditions. Trial registration The original PICTURE trial was registered at ClinicalTrials.gov (NCT03315390 registered on 17 October 2017) and in the German Clinical Trials Register (DRKS00012589). The present study is a secondary analysis of data from the PICTURE trial. Safety outcomes were not assessed in this secondary analysis harms have been reported in the primary trial publication [8]. Trial registration ClinTrials.gov NCT03315390 DRKSID DRKS00012589</p>