Prospective bidirectional associations between depression and chronic kidney disease

study design

The CHARLS study used a multistage cluster sampling method to select participants from 28 provinces in mainland China23. A total of 17,708 participants from 10,257 households recruited from 28 provinces in China were included at baseline (2011-2012, wave 1). CHARLS respondents are then followed up every 2 years, using a face-to-face computer-assisted personal interview. Two subsequent follow-ups were conducted in 2013-2014 (wave 2) and 2015-2016 (wave 3), respectively. At each wave, trained staff conducted face-to-face interviews to collect information including participants’ socio-demographic characteristics, medical histories, health behaviors, and measures of general health and functioning, including including depressive symptoms. A more detailed description of CHARLS can be found in previous posts23.24. This study was approved by the Peking University Biomedical Ethics Review Board, and all participants signed informed consents. The ethics request for the collection of human subject data in CHARLS was approved by the Peking University Biomedical Ethics Review Board (IRB00001052-11,015). All study methods were carried out on the basis of the Declaration of Helsinki.

Study sample

In Study I, individuals who met all of the following criteria were included: aged at least 45 years, reporting information on the Center for Epidemiological Studies Scale 10 of Depression (CESD-10) at the wave 1, with no CKD diseases at wave 1 and having reported CKD information in wave 3. Finally, a total of 7637 people were eligible for further analysis (Fig. 1A). In Study II, individuals who met all of the following criteria were included: at least 45 years of age, reporting CKD information and at wave 1, without depression at wave 1 and reporting information on CESD-10 at wave 3. Finally, a total of 6337 individuals were eligible for further analysis (Fig. 1B).

Figure 1

Flowchart of study population selection for Study I (A) and Study II (B).

Assessments of depression, CRI and covariates

The CESD-10 was administered to measure depressive symptoms at baseline and at each CHARLS follow-up visit25which has been shown to be a reliable and valid approach to detecting depression in Chinese adults26.27. The CESD-10 scale incorporates depressed mood and positively affected parts and consists of ten items. His total scores range from 0 to 30, with higher scores indicating higher degrees of depressive symptoms. A cutoff of 10 was used to identify people with depression28.

The CRI was based on doctors’ self-reported diagnosis “Has a doctor ever told you that you have kidney disease?” or personal eGFR level29. If an affirmative response was given by an individual or their proxy respondent or eGFR 2, then the individual would be classified as suffering from the first CKD in their life (excluding tumor or cancer). Serum creatinine was measured using a zero-flow and compensated Jaffe creatinine method. The eGFR assessment used the creatinine equation from the Chronic Kidney Disease Epidemiology Collaboration with an adjusted coefficient of 1.1 for the Chinese population30.

Other covariates collected included age, sex, place of residence (rural or urban), smoking status (ever or never smoked), alcohol status (ever or never drunk), body mass index (weight in kilograms divided by height squared in meters), presence or absence of other chronic diseases (defined by self-reported history of dyslipidemia, diabetes, cancer, heart disease, stroke, asthma, lung disease, liver disease, digestive disease and memory impairment). “Never smoked” means that the respondent reports having smoked at some time, and “never smoked” means the respondent reports that they have never smoked. “Ever drank” means that the respondent reports having had an alcoholic drink in the past, and “never had a drink” means that the respondent reports not having had an alcoholic drink in the past. Additionally, dyslipidemia (defined by a history of dyslipidemia, or triglycerides ≥ 2.26 mmol/L, or total cholesterol ≥ 6.22 mmol/L, or high density lipoprotein cholesterol 31.

statistical analyzes

Baseline participant characteristics are presented as percentages for categorical variables, means with standard deviation for normally distributed variables, and medians with interquartile range for non-normally distributed variables. Demographic and clinical characteristics were compared between groups by Student’s t-tests or Wilcoxon’s rank-sum tests for continuous variables and the χ2 test for categorical variables, where appropriate. Multivariate logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (95% CIs) of the relationships between depression and CKD. Potential covariates, such as age, sex, place of residence, level of education, smoking, alcohol consumption, body mass index, systolic blood pressure and medical history (dyslipidemia, diabetes, cancer, heart disease, stroke, asthma, lung disease, liver disease, digestive disease and memory problem) were included in the multivariate models. Additionally, subjects were further divided into three groups based on CESD-10 scores: 2; 60 ≤ eGFR 2; eGFR 2 or with renal diseases reported in Study II. Subgroup analyzes were then performed to assess the association between depression and CKD according to sex, age, place of residence, smoking, alcohol consumption, level of education, history of hypertension and diabetes. In sensitivity analyses, we further adjusted baseline eGFR level in Study I and baseline CESD-10 scores in Study II based on multivariate models. two tails P