Effectiveness of the Smoke Free App for Smoking Cessation -- Results of RAUCHFREI, a Randomised, Double-blind, Controlled, Two-arm, Parallel, Nationwide, Decentralised, Fully Remote Clinical Trial in Germany

ObjectivesUptake of evidence-based smoking cessation support remains limited. Digital interventions offer the prospect of scalable and highly accessible support. Smoke Free, a digital mobile application using established behaviour change techniques, has shown promise, but no large-scale randomised controlled efficacy trial has yet been conducted. We assessed its effectiveness for smoking cessation. DesignIn this prospective, randomised, controlled, two-arm, parallel clinical trial with 6-month follow-up, study personnel and patients were blinded. SettingThe trial was conducted nationwide in Germany, utilising a decentralised, fully remote trial design. Enrolment took place digitally after receiving brief advice from a healthcare professional, following guidelines for primary care. ParticipantsOut of a volunteer sample of 1850 patients assessed for eligibility, 1466 adult cigarette smokers who had at least moderate cigarette dependence (F17.2, FTCD[&ge;]3) were recruited between August 2023 and February 2024; 84.1% (1233 participants) completed the primary outcome measure. InterventionsThe intervention group (IG) received the Smoke Free app including behaviour-change missions and gamification elements, while the control group (CG) received a text-only cessation information app. Both groups received brief advice from a healthcare professional. Main outcome measuresThe prespecified primary outcome was self-reported 7-day point-prevalence abstinence from combustible tobacco at 6 months post-randomisation; secondary outcomes included biochemical validation of abstinence in participants providing a saliva sample (59% of eligible participants). ResultsSelf-reported abstinence (primary outcome) was significantly higher in the IG compared with the CG (283 [39.3%] vs. 182 [24.4%], OR=2.01, 95% CI 1.60 to 2.50, p<0.0001). The NNT was 6.7 (5.1 to 9.8). The effect was consistent with biochemical validation (OR=1.76, 95% CI 1.27 to 2.44, p<0.0001) and across secondary outcomes and sensitivity analyses. The 6-month follow-up rates for the primary outcome did not differ between groups (IG: 601 [83.5%]; CG: 632 [84.7%]; p=0.52). Eighty-four serious adverse events were reported by 75 participants (IG: 31, 4.3%; CG: 44, 5.9%; p=0.53); none were treatment-related. ConclusionsThe Smoke Free app is effective for aiding smoking cessation in at least moderately dependent cigarette smokers compared with an informational app when provided as an adjunct to brief advice from a healthcare professional. Trial registrationThe trial was registered with the German Clinical Trials Register (DRKS00031140). FundingSmoke Free 23 GmbH (for-profit company).