Impact of POPulation Medicine Multimorbidity Intervention in Xishui County (POPMIX) on suspected asthma patients: Protocol of the POPMIX-Asthma cluster-randomized controlled trial

Background Asthma is a common chronic disease responsible for a considerable disease burden in China and around the world. Despite its burden, there is substantial unmet need for asthma care, including screening, diagnosis, treatment, and management. Symptom-based screening for asthma could support identification of undiagnosed asthma patients, as well as reference to higher-level hospitals for formal diagnoses and treatment. This study focuses on identifying suspected asthma patients and encouraging them to seek formal diagnoses and treatment. This approach aligns with the novel concept of population medicine, which aims to maximize overall population health rather than focusing on individual patients within the health system. Methods We are conducting a two-arm population-based stratified clustered randomized controlled trial (cRCT) to evaluate the effectiveness of a population medicine multimorbidity intervention package. The intervention integrates community screening, chronic disease management, patient education, digital follow-up, and team-based care. The trial is being implemented in Xishui County, Guizhou Province, a mountainous low-resource county in Southwestern China, covering 26 townships and more than 300,000 permanent residents. We considered each of the 26 townships in Xishui County as a cluster and stratified them into large and small townships based on population size. Townships with an above-average population were designated as “large,” and those with a below-average population were designated as “small.” We randomized the same number of residents in each township stratum (large and small) to undergo the European Community Respiratory Health Survey (ECRHS) for identifying suspected asthma patients. Individuals identified as suspected asthma patients were considered study participants and subsequently enrolled in the intervention or control arm. The target sample size is approximately 11,100 individuals. As of July 2025, 11,080 suspected asthma patients had been recruited into the study, with 5,521 entering the intervention arm and 5,559 entering the control arm. All participants are followed for one year, with one telephone follow-up at month three and in-person follow-ups at months six and 12. Primary outcomes include the number of chronic conditions controlled, whether the participant received lung function testing, and Asthma Control Test (ACT) score. In addition, we are evaluating 42 secondary outcomes covering physiological and functional indicators such as lung function, health-related quality of life, mental health, behavioral risk factors, healthcare utilization, productivity loss, knowledge of asthma and chronic obstructive pulmonary disease (COPD), and care cascade indicators for asthma and other chronic diseases. Discussion This cRCT has been featured as an important case study in the Lancet Commission on Investing in Health report to evaluate the effectiveness of the integrated intervention package on priority conditions. The trial was designed under population medicine principles, with an aim providing holistic care and enhancing the overall health status of suspected asthma patients. The results of the trial will inform the next generation of multimorbidity management and population medicine practices among global health authorities and practitioners. Trial registration ClinicalTrials.gov Identifier: NCT06457009. Registered on June 7, 2024.