Evaluation of two easy-to-implement digital breathing interventions in the context of daily stress levels in a series of N-of-1 trials: results from the Anti-Stress Intervention Among Physicians (ASIP) Study

Physicians face intense work-related stress, which can harm their health, increase the risk of medical errors, lower healthcare quality, and increase costs within the healthcare system. In this 4-week intervention study, individual-level and population-level effects of two short and easy-to-perform breathing exercises designed to reduce stress are evaluated among 76 physicians in residency in Germany in a series of N-of-1 trials. Levels of stress and levels of stress expected for the following day were assessed electronically every day via the StudyU App. Intervention effects were estimated using Bayesian linear regression models and were overall small on the population level but they showed large heterogeneity between individuals with strong effects for selected individuals. Twenty-seven participants benefitted from the anti-stress exercises. Three (Mindfulness Breathing) and seven participants (box breathing) had a ≥70% probability for a daily stress reduction of ≥0.5 points and thereby fulfilled our responder criteria. On average, 4.5 months after completion of the individual N-of-1 trials, a follow-up survey among all participants was conducted to assess sustainability of the interventions. Although general implementation of these anti-stress exercises cannot be recommended, they can be highly effective for selected individuals and potentially beneficial in specific subgroups.