The association between Vapor Pressure Deficit and arthritis: The evidence from CHARLS

Abstract Objective To explore the relationship between atmospheric humidity index and arthritis. Methods This prospective cohort study uses data from the China Health and Retirement Longitudinal Study (2011–2020) and the first 1 km high-resolution atmospheric humidity index dataset in China. Non-arthritis subjects from 2011 were selected for the study. Atmospheric humidity index was the primary exposure factor, and arthritis incidence was the outcome. A logistic regression risk model and restricted cubic splines (RCS) were used to analyze the relationship between atmospheric humidity index and arthritis. Subgroup analysis was conducted using stratified logistic regression to confirm the stability of the results. Results A total of 6,300 without preexisting arthritis were included, during which 1,784 were diagnosed with arthritis over a 10-year follow-up period. Individuals diagnosed with arthritis had lower Vapor Pressure Deficit (VPD) levels in their living environment (5.17 ± 0.83 vs. 5.27 ± 0.83, p < 0.0001) compared to the non-arthritis group. The five logistic regression risk models all show that there is a linear relationship between VPD and arthritis, and even after VPD is classified, this result has not changed. Restricted cubic spline (RCS) analysis indicated no nonlinear relationship between VPD and arthritis incidence (P-nonlinearity > 0.05). Interestingly, we observed that arthritis incidence significantly decreased with higher VPD levels (p < 0.05). Using a VPD median of 5.24 as the cutoff, the relationship was more pronounced in low VPD environments (OR = 0.835 [0.711, 0.980], OR = 0.805 [0.680, 0.953], OR = 0.807 [0.681, 0.956], OR = 0.76 [0.618, 0.934], OR = 0.763 [0.620, 0.938]). The final subgroup analysis indicated a significant interaction between residence and the VPD-arthritis relationship (P < 0.001). In rural populations, higher VPD levels significantly reduced arthritis incidence (OR = 0.787 [0.721, 0.858]). Conclusion Increased vapor pressure deficit (VPD) is associated with a lower incidence of new arthritis cases. Rural residents should pay particular attention to weather changes to reduce arthritis risk.