Association of body mass index variability with multimorbidity in the elderly

Background: Body mass index (BMI) variability has been found to be associated with higher mortality and aging related chronic disease. However, there are few studies on the relationship between BMI variability and multimorbidity. Objectives: To investigate the relationship between BMI variability and comorbidity and provide evidence-based medical evidence for finding therapeutic targets to reduce the incidence of multimorbidity. Methods: This was an observational, descriptive, cross-sectional study. We included 14195 people more than 60 years old from 1999–2018 National Health and Nutrition Examination Surveys (NHANES). All samples had complete chronic disease information and BMI recordings. BMI variability were calculated by average successive variability (ASV). Participants were stratified by BMI Variability into five groups and ORs and 95%CIs were calculated compared with lowest quartile group. Results: For elderly people with chronic disease, the incidence of multimorbidity was from 68.0–95.5%, and it increased from the lowest to the highest quartile groups in most chronic disease(P < 0.01). Stroke was the most common disease coexisting with other chronic diseases (87.2–95.5%), followed by heart disease (85.4–94.0%). While in hypertension elderly people, the ratio was relatively lower (68.0–80.1%). In both three models, the odds ratios (ORs) of multimorbidity incidence significantly increased in the groups with high BMI variability (P < 0.001). And for multimorbidity patients, the ORs (95% CI) were increased from quintile 1 to quintile 5 group (P < 0.001). Conclusions: BMI variability was associated with incidence of multimorbidity, and it seems that higher weight variation showed a large response.