Background: The Clalit Active Cohort Study (CACS) assess the impact of lifestyle factors, particularly physical activity, on short- and long-term health outcomes using real-world data. Launched in January 2021, CACS focuses on Clalit Health Services members with supplemental health insurance who use the Clalit Active smartphone app. Methods: The study integrates data from the Clalit Active app with electronic health records from CHS, covering primary and secondary care, hospitalizations, medications, laboratory results, and imaging. The cohort currently includes 622 584 participants and continues to grow. Results: The app monitors various health-related behaviors, including physical activity and sleep. Preliminary findings show significant variations in daily step counts based on sociodemographic and clinical factors. Substantial differences were found between app users and non-users app users and non-users. On average, males recorded higher daily step counts compared to females, and individuals under the age of 40 demonstrated greater activity levels than older participants. Participants with pre-existing comorbidities demonstrated lower activity levels. Conclusions: CACS is a powerful resource for researchers and policymakers, providing insights into the relationship between lifestyle factors and health outcomes within a diverse population. Findings can inform public health policies and guide the lifestyle interventions, highlighting the potential of integrating smartphone data with electronic health records to improve health outcomes
