Temporal associations of BMI transition with metabolic inflammation in allergic rhinitis: A retrospective cohort study

Background In patients with allergic rhinitis (AR), the dynamic longitudinal association between transition from normal body mass index (BMI) to overweight/obesity and metabolic inflammation remains unclear. Methods We conducted a retrospective longitudinal cohort study involving 1715 AR patients with normal baseline BMI between 2014 and 2025 at the Affiliated Hospital of Guangdong Medical University in Zhanjiang, Guangdong, China. Using targeted maximum likelihood estimation with time-window analysis, we estimated the average treatment effects of BMI increase on inflammatory and metabolic markers over 1–3 years and quantified risks of metabolic diseases. Results BMI transition was associated with progressively increased systemic inflammation and persistent metabolic dysregulation. Inflammatory markers showed a time-dependent increase, whereas metabolic abnormalities, characterized by elevated triglycerides and reduced high-density lipoprotein cholesterol, appeared earlier and remained stable. BMI gain was also associated with increased risks of several metabolic diseases, particularly fatty liver disease. Conclusion In AR patients, transitioning from normal BMI to overweight or obesity was associated with a gradual increase in systemic inflammation and persistent metabolic dysfunction that was associated with increased risks of various metabolic diseases. When implementing weight management for patients with AR, it is recommended to monitor changes in body weight over time and intervene early in the weight gain process.