Decision aid and cost compensation influence uptake of PSA-based early detection without affecting decisional conflict: a cluster randomised trial

Abstract

International guidelines recommend to inform men about the benefits and harms of prostate specific antigen (PSA) based early detection of prostate cancer. This study investigates the influence of a transactional decision aid (DA) or cost compensation (CC) for a PSA test on the decisional behaviour of men. Prospective, cluster-randomised trial to compare two interventions in a 2 × 2 factorial design: DA versus counselling as usual, and CC versus noCC for PSA-testing. 90 cluster-randomised physicians in the administrative district of Muenster, Germany recruited 962 participants aged 55-69 yrs. in 2018. Primary endpoint: the influence of the DA and CC on the decisional conflict. Secondary endpoints: factors which altered the involvement of the men regarding their decision to take a PSA-test. The primary endpoint was analysed by a multivariate regression model. The choice to take the PSA test was increased by CC and reduced by the DA, the latter also reduced PSA uptake in men who were offered CC. The DA led to an increase of the median knowledge about early detection, changed willingness to perform a PSA test without increasing the level of shared decision, giving participants a stronger feeling of having made the decision by themselves. The DA did not alter the decisional conflict, as it was very low in all study groups. DA reduced and CC increased the PSA uptake. The DA seemed to have a greater impact on the participants than CC, as it led to fewer PSA tests even if CC was granted.Trial registration: German Clinical Trial Register (Deutsches Register Klinischer Studien DRKS00007687). Registered: 06/05/2015. https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00007687 .

Figure 1

Pictogram of the “arriba-PSA”. It combines information from eight other pictograms included in the transactional DA based on 1000 men (1 circle = 1 man) in the age range of 55–69 years undergoing PSA based early detection of PCa during a period of ten years. It contains information about: dying of PCa within the next ten years; being diagnosed with PCa (risk of a clinically significant vs. not significant cancer) within the next ten years; having false-positive or false-negative PSA test results (risk of “unnecessary” prostate biopsies vs. “false reassurance”) referring to a period of four years only. ¹Overdiagnosis^,: diagnosis of PCa unlikely to harm the man during his life-time. PSA = prostate specific antigen.

Figure 2

CONSORT flow diagram of the cluster-randomised controlled trial “PSAInForm” with a 2 × 2 factorial design. 90 physicians are randomised to one of four arms (A-D) before they start to recruit participants. PSA = prostate specific antigen.

Figure 3

Boxplots comparing the DCS score between study arms. (a) Consultation with DA (arm A + B): Q25% = 3.1; Median = 6.2; Q75% = 14.1 vs. consultation without DA = noDA: Q25% = 0; Median = 6.2; Q75% = 12.5. (b) Consultation with cost compensation CC (arm A + C): Q25% = 1.6; Median = 6.2; Q75% = 12.5 vs. without cost compensation = noCC (arm B + D): Q25% = 2.5; Median = 6.2; Q75% = 14.1. DCS = decisional conflict scale: 0–100; higher values indicate greater decisional conflict.