Evaluating a Provincial Chronic Disease Plan in Cold Rural China: A Decade-Long Interrupted Time Series Analysis (2015-2025)

Background China faces a growing burden of chronic non-communicable diseases (NCDs), particularly in resource-limited rural areas with extreme climatic conditions. To address this challenge, the National Chronic Disease Prevention and Control Initiative, implemented at the provincial level in Heilongjiang Province (2017–2025). However, evidence on the effectiveness of subnational prevention strategies in such settings remains scarce. This study aimed to evaluate the impact of this policy on chronic disease prevalence trends in a cold rural region. Methods We conducted a longitudinal interrupted time series analysis using data from a natural population cohort in Mingshui County (n = 10694 participants, mean age of 57·98 ± 8·80 years, 61·75% female) from 2015 to 2025. Annual prevalence, proportional distribution, and year-over-year growth rates for eight major categories of chronic diseases were calculated. Segmented regression models assessed policy effects on prevalence trends, while network analysis visualized multimorbidity patterns. Results The overall prevalence of chronic diseases increased from 2015 to 2025, but policy implementation in 2019 significant slowed the growth trajectory (slope change = -0·542% per year, p < 0·05). Disease-specific trends were heterogeneous: cardiovascular disease maintained the highest prevalence (2015: 23·1%; 2025: 67·0%), its annual growth rate demonstrated the most significant deceleration post-policy (difference = -5·536%), while respiratory diseases showed accelerated growth (difference = + 0·499%). Multimorbidity prevalence increased persistently, with a core cluster of cardiovascular, endocrine/metabolic, digestive, and respiratory diseases forming the central pattern of disease co-occurrence. Conclusions The provincial chronic disease prevention initiative effectively curbed the growth of certain diseases like cardiovascular conditions, but its impact on respiratory diseases and multimorbidity remains limited. These findings underscore the necessity for more targeted interventions addressing region-specific risk factors and multimorbidity patterns in cold rural settings. This study provides critical evidence for optimizing chronic disease control strategies in similar high-risk environments globally.