Effects Of Skeletal Muscle Mass And Obesity On Osteoporosis In Older Women In Tiexi District,shenyang:A Cohort Study

Objective: Due to the influence of various factors,older women are prone to face the problems of skeletal muscle mass loss and obesity at the same time.Many previous studies have shown that skeletal muscle mass loss is a risk factor for osteoporosis,and obesity is a protective factor for osteoporosis.However,the effect of skeletal muscle mass loss combined with obesity on osteoporosis is still unclear.The purpose of this study was to prospectively analyze the impact of skeletal muscle mass and obesity on the risk of osteoporosis in older women.Methods: Based on the data of major chronic diseases cohort in Northeast China from2017 to 2021,this study applied the method of prospective cohort study.The subjects of the study were elderly women over 60 years old in Tiexi District,Shenyang City.A total of 969 people were included after excluding individuals with osteoporosis,malignant tumor or liver disease at baseline,missing baseline data,inability to communicate normally,missing follow-up and taking drugs that affect bone in the past year or more than six months.Osteoporosis was defined according to the standard of the World Health Organization(WHO).The one-way ANOVA was used to compare the continuous variables in the baseline data,and the chi-square test and Fisher’s exact test were used to compare the classification variables.The changes in skeletal muscle mass,various obesity indicators and bone mineral density at the end of follow-up in older women were analyzed by heatmap.Stratified according to various obesity indicators.The COX proportional risk model was used to analyze the relationship between the skeletal muscle mass of obese and non-obese older women and the risk of osteoporosis.The interaction between obesity and skeletal muscle mass loss on osteoporosis was analyzed through joint grouping analysis.The Receiver Operating Characteristic(ROC)curve was used to evaluate the predictive effect of baseline skeletal muscle mass index on the risk of osteoporosis in the next three years.Results: During the follow-up period from 2018 to 2021,there were 267 new cases of osteoporosis,with a total follow-up time of 2379 person years and an incidence density of 11.22%.Baseline analysis showed that the skeletal muscle mass,skeletal muscle mass index,waist circumference,waist height ratio and body mass index of the osteoporosis group were lower than those of the non-osteoporosis group.The heatmap showed that the bone mineral density of the older women with lower skeletal muscle mass index and higher obesity index was relatively lower.Subgroup analysis showed that after adjusting for some and all confounding factors,the Hazard ratios(HRs)of skeletal muscle mass and the risk of osteoporosis were less than 1,and the 95%confidence interval(CI)did not include 1.And joint grouping analysis showed that the interaction P-values were all greater than 0.05.Moreover,the ROC curve showed that the area under curve(AUC)of obese group was significantly larger than that of nonobese group(P<0.05).Conclusion: Although obesity may be an independent protective factor for osteoporosis,even under the influence of obesity,the reduction of skeletal muscle mass in older women will still increase the risk of osteoporosis,and in obese women,skeletal muscle mass can better predict the risk of osteoporosis.