Background To support the optimisation of supervised exercise therapy (SET) in patients with intermittent claudication, we developed personalised outcomes forecasts (POFs), which visualise estimated walking distance and quality of life for individual patients. The POFs may enable healthcare professionals, such as physical and exercise therapists, to improve shared decision-making and patient outcomes. Objectives To assess differences in patient outcomes (functional walking distance, maximal walking distance and health-related quality of life) and the level of shared decision-making before and after the implementation of POFs in the conservative treatment of patients with intermittent claudication. Methods An interrupted time series design was used to compare preimplementation and postimplementation differences on patient outcomes. Using routinely collected data, differences from baseline to 6 months were compared between patients before and patients after the implementation. To compare levels of shared decision-making, we conducted observations of initial consults within a sample of physical or exercise therapists both before and after the implementation. Audiorecords of observations were scored on shared decision-making using the OPTION-5 instrument. Results Differences in improvements between patients with whom POFs were discussed (n=317) and patients before the implementation of POFs (n=721) did not reach statistical significance for both functional walking distance (experimental vs. control=+23%, p=0.11) and maximal walking distance (experimental vs. control=+21%, p=0.08). For health-related quality of life, the POFs-informed patients showed a statistically significant greater improvement of 4% (p=0.04). Increased levels of shared decision-making were observed in postimplementation consults (n=20) when compared with preimplementation consults (n=36), as the median OPTION-5 total score showed a statistically significant increase from 45 to 55 points (p=0.01). Conclusions Integrating POFs into daily practice ...