Physical Activity and Blood Lead in the Depression Predicted by the Nomogram

Background: Less attention has been paid to predictive models using exercise and blood lead levels to screen for depression risk in the general population. Methods: Data were collected from the National Health and Nutrition Examination Survey 2007-2014. Nomogram was developed based on the results of logistic regression. Stratified analysis was performed to find the association between physical activity, blood lead and risk of depression. Outcomes: The positive rate of detecting depression among participants in the training and validation cohorts was 1154 (19·4%) and 855 (21·3%). Age, marital status, race, income, sleep duration, hypertension, physical activity, and blood lead were used to develop a nomogram for depression risk assessment. The nomogram showed good discrimination ability, with a bootstrap-corrected C index of 0·68 (95% CI, 0·67-0·70), and an externally validated C index of 0·66 (95% CI, 0 64-0·68) respectively, and had well-fitted calibration curves. As the risk of depression increased, the blood lead ratio gradually increased at Q4 levels and decreased at Q1; the proportion of sedentary gradually increased, while other physical activity gradually decreased. Interpretation: The developed nomogram provides a useful tool for the screening, assessment and treatment of depression in populations. The study also highlights the association between sedentary, high blood lead and the risk of developing depression, and recommends that hypertension with sleep disorders reduce all forms of exercise. Funding Information: This work was supported by funds from the National Science Foundation for Young Scientists of China (grant number 81502889) and the National Natural Science Foundation of China (grant number 82073666 and grant number 71473063). Declaration of Interests: The authors have no conflicts of interest to declare. Ethics Approval Statement: NHANES studies are approved by the local institutional review board. Survey participants are asked to sign written consent. See the NHANES website (www.cdc.gov/nchs/nhanes.htm) for further details.