Objective:To explore the association of central obesity, pain, their joint effect, and interaction with frailty in middle-aged and old people in China.Methods:A total of 14 359 participants aged ≥45 years in 2011, 2013 and 2015 were selected from the China Health and Retirement Longitudinal Study to construct a cohort database. Cox proportional hazards regression models were used to estimate the association of waist-to-height ratio (WHtR) and pain with the risk for frailty. Joint effect and interaction analyses were performed.Results:In the follow-up of 77 783 person-years, frailty developed in 3 198 participants, with an incidence density of 41.11 per 1 000 person-years. Compared with the Q1 level of WHtR, its Q2, Q3 and Q4 level increased risk for frailty by 17% ( HR=1.17, 95% CI: 1.05-1.31), 24% ( HR=1.24, 95% CI: 1.11-1.40), and 43% ( HR=1.43, 95% CI: 1.25-1.63), respectively. Compared with painlessness, suffering from pain increased the risk for frailty by 97% ( HR=1.97, 95% CI: 1.83-2.11), and having 1, 2, and ≥3 pain sites increased the risk by 42% ( HR=1.42, 95% CI: 1.25-1.61), 86% ( HR=1.86, 95% CI: 1.64-2.11), and 138% ( HR=2.38, 95% CI: 2.18-2.60), respectively. The results of restricted cubic spline showed that WHtR level was associated with the risk for frailty in a J-type dose-response relationship (total P<0.001, nonlinear P<0.001), and pain quantity was positively associated with the risk in a nonlinear dose-response relationship (total P<0.001, nonlinear P<0.001). Threshold effect analysis revealed that the inflection points of WHtR and pain site number were 0.46 and 2.00, respectively ( P<0.001). Joint effect analysis showed that the Q2, Q3 and Q4 levels of WHtR combined with pain increased the risk for frailty by 146% ( HR=2.46, 95% CI: 2.11-2.87), 169% ( HR=2.69, 95% CI: 2.30-3.16), and 157% ( HR=2.57, 95% CI: 2.18-3.03). Conclusions:The risk for frailty increased with the level of WHtR and the number of pain sites in middle-aged and old people, and there was joint effect between WHtR and pain. Comprehensive management and intervention of obesity and pain are significant for the early prevention of frailty.

Objective:To explore the association of central obesity, pain, their joint effect, and interaction with frailty in middle-aged and old people in China.Methods:A total of 14 359 participants aged ≥45 years in 2011, 2013 and 2015 were selected from the China Health and Retirement Longitudinal Study to construct a cohort database. Cox proportional hazards regression models were used to estimate the association of waist-to-height ratio (WHtR) and pain with the risk for frailty. Joint effect and interaction analyses were performed.Results:In the follow-up of 77 783 person-years, frailty developed in 3 198 participants, with an incidence density of 41.11 per 1 000 person-years. Compared with the Q1 level of WHtR, its Q2, Q3 and Q4 level increased risk for frailty by 17% ( HR=1.17, 95% CI: 1.05-1.31), 24% ( HR=1.24, 95% CI: 1.11-1.40), and 43% ( HR=1.43, 95% CI: 1.25-1.63), respectively. Compared with painlessness, suffering from pain increased the risk for frailty by 97% ( HR=1.97, 95% CI: 1.83-2.11), and having 1, 2, and ≥3 pain sites increased the risk by 42% ( HR=1.42, 95% CI: 1.25-1.61), 86% ( HR=1.86, 95% CI: 1.64-2.11), and 138% ( HR=2.38, 95% CI: 2.18-2.60), respectively. The results of restricted cubic spline showed that WHtR level was associated with the risk for frailty in a J-type dose-response relationship (total P<0.001, nonlinear P<0.001), and pain quantity was positively associated with the risk in a nonlinear dose-response relationship (total P<0.001, nonlinear P<0.001). Threshold effect analysis revealed that the inflection points of WHtR and pain site number were 0.46 and 2.00, respectively ( P<0.001). Joint effect analysis showed that the Q2, Q3 and Q4 levels of WHtR combined with pain increased the risk for frailty by 146% ( HR=2.46, 95% CI: 2.11-2.87), 169% ( HR=2.69, 95% CI: 2.30-3.16), and 157% ( HR=2.57, 95% CI: 2.18-3.03). Conclusions:The risk for frailty increased with the level of WHtR and the number of pain sites in middle-aged and old people, and there was joint effect between WHtR and pain. Comprehensive management and intervention of obesity and pain are significant for the early prevention of frailty.

Objective:To explore the association between triglyceride glucose index (TyG)- waist to height ratio (WHtR)(TyG-WHtR) and cognitive impairment in middle-aged and elderly population.Methods:A cohort database was constructed using the data from the China Health and Retirement Longitudinal Study, with 8 946 participants in 2011 and 2015 as the baseline population. Cox proportional hazards regression models were used to estimate the association between TyG-WHtR levels at baseline and the risk of cognitive impairment in middle-aged and elderly population. The analysis was stratified by age and gender, respectively.Results:A total of 8 946 participants were included, with an average follow-up of 7.08 person-years and incidence density of cognitive impairment for 21.15 per 1 000 person-years. Compared with the Q1 level of TyG-WHtR, its Q3 and Q4 level increased the risk of cognitive impairment by 32% ( HR=1.32, 95% CI: 1.09-1.60) and 47% ( HR=1.47, 95% CI: 1.14-1.91), respectively. Trend test showed that the risk of cognitive impairment increased with the increase of TyG-WHtR level, and there was a dose-response relationship ( P=0.001). Stratified analysis showed that in the population aged 45-59 years, compared with the Q1 level of TyG-WHtR, its Q3 level increased the risk of cognitive impairment by 34% ( HR=1.34, 95% CI: 1.02-1.78). In the population aged 60 years and above, compared with the Q1 level, its Q3 and Q4 level increased the risk of cognitive impairment by 31% ( HR=1.31, 95% CI: 1.01-1.72) and 63% ( HR=1.63, 95% CI: 1.15-2.31), respectively. In the male group, there was no significant association between TyG-WHtR level and the risk of cognitive impairment ( P>0.05). In the female group, compared with the Q1 level of TyG-WHtR, its Q4 level increased the risk of cognitive impairment by 76% ( HR=1.76, 95% CI: 1.26-2.46). Conclusions:Middle-aged and elderly population with a higher TyG-WHtR level may increase the risk of cognitive impairment, and there were age and sex differences. Early cardiovascular health management and scientific and reasonable weight management are of great significance to preventing cognitive impairment.