Associations between pulmonary function and depression: evidence from the CHARLS cohort 2015-2018

Abstract

Background: The relationship between lung function and depression in middle-aged and older adults remains poorly understood. To address this knowledge gap, we conducted cross-sectional and longitudinal analyses using data from the nationally representative China Health and Retirement Longitudinal Study (CHARLS) to examine the association between peak expiratory flow (PEF) status and depression among middle-aged and older Chinese adults.

Methods: A total of 15,137 participants aged 45 years and older were included from the 2015 China Health and Retirement Longitudinal Study (CHARLS). Participants were categorized into three PEF status groups based on their percentage of predicted PEF: severe impairment (<80%), average lung function (80-100%), and good lung function (≥100%). A total of 12,304 participants were included in the longitudinal analysis from 2015 to 2018. To address potential confounding, propensity score matching was employed using a gradient-boosting model to balance covariates between participants with and without depression. Logistic regression analyses as well as restricted cubic spline (RCS) regression analyses were performed to examine the association between (PEF) status and depression incidence.

Findings: The prevalence of depression was 9.53% (n = 1,044) in the cross-sectional sample, with higher rates observed in participants with poorer lung function (9.53, 7.11, and 5.03% for good, moderately good, and poorer lung function, respectively). During a 3.6-year follow-up, 6.73% (n = 130) of participants developed depression. Fully adjusted logistic regression analysis demonstrated a significant inverse linear association between PEF percentage and depression risk (OR: 0.898, 95% CI: 0.862-0.935, per 1 SD increase). These findings were corroborated by restricted cubic spline (RCS) regression analysis, which revealed a linear relationship without evidence of nonlinearity (P for nonlinearity = 0.631).

Conclusion: Our study revealed a noteworthy correlation between PEF percentage and depression among the middle-aged and older population. The PEF percentage emerges as a valuable tool that may enhance the primary prevention and treatment of depression.

Keywords: CHARLS; cognitive; depression; peak expiratory flow; prospective cohort study.

Figure 1

Study cohort. Inclusion and exclusion criteria for the study cohort (n = 12,304).

Figure 2

Illustrates the relative importance of these covariates in predicting propensity scores.

Figure 3

(A) An RCS curve illustrating the association between PEF percentage and incident depression. The model was adjusted for potential confounders including age, gender, baseline depression status, health satisfaction, childhood health, marriage satisfaction, ASM/Ht², systolic blood pressure, pulse rate, eyesight, hearing, local service satisfaction, pension insurance, memory function, sleep duration (hours), difficulty with stooping and sitting difficulties. The overall significance level for the association is highly significant (p < 0.001), while the nonlinear trend is not significant (P for nonlinearity = 0.631). (B) An RCS curve depicting the relationship between cognitive function and PEF percentage. In this model, the overall p-value is 0.888, indicating that the association is not statistically significant, while the nonlinear trend p-value is 0.742, suggesting some nonlinearity in the relationship. The curve demonstrates a complex pattern of ORs as the PEF percentage changes. However, further interpretation should be made in light of the study design and other statistical analyses.

Figure 4

Subgroup analysis of depression risk by demographic, socioeconomic, and health-related factors, 2015–2018.