Data was derived from the China Health and Retirement Longitudinal Study (CHARLS), which is a high quality nationally representative longitudinal survey of Chinese residents ages 45 or older and their spouses, including assessments of social, economic, and health status . The baseline national wave of CHARLS was being fielded in 150 counties (or districts) and 450 villages (or resident) committees from 28 provinces (or autonomous regions, municipalities) in 2011, and three follow-up surveys were carried out in 2013 (wave 2), 2015 (wave 3) and 2018 (wave 4). Anthropometric measurements of height, weight, waist circumference, lung capacity, grip strength, speed of repeated chair stand, blood pressure, walking speed, and balance tests are conducted at every follow up wave, while blood-sample is collected once in every two follow-up cycles. All data were collected by face-to-face computer-assisted personal interviews (CAPI) with a response rate over 80% at baseline. By the time the follow-up was completed in 2018, the sample had covered a total of 19,000 respondents in 12,400 households.
Data from the baseline (2011) and follow-up waves were used in this investigation (2013, 2014, 2015 and 2018). Only male and female participants aged 50 and older at the time of the 2018 follow-up (n = 17,610; mean [SD] age at baseline, 65.3 [9.4] years) were included in our analytic sample.
Early life adversity exposure
The Life History Survey Questionnaire, which asked individuals if they suffered any of 11 particular adversities before the age of 17, was used to analyze multiple ELA events marked by threat and deprivation in the Wave of 2014. Threat-related ELA included the following six specific adversities: (1) Unsafe community dwelling (Was it safe being out alone at night in the neighborhood where you lived as a child?); (2) Peer bullying (When you were a child, how often were you picked on or bullied by kids in your school? Is it often, sometimes, rarely or never?); (3) Female guardian physical abuse (When you were growing up, did your female guardian ever hit you?); (4) Male guardian physical abuse (When you were growing up, did your male guardian ever hit you?); (5) Sibling beat (When you were growing up, how often did your brother or sister ever hit you?); (6) Parental conflict (Did your parents often quarrel?).
Deprivation-related ELA included the following five specific adversities in childhood: (1) Biological mother absent (Before you were age 17, was it your biological mother, adopted mother or stepmother who spent the most time raising you?); (2) Biological father absent (Before you were age 17, was it your biological father, adopted father or step father who spent the most time raising you?); (3) Food scarcity (When you were a child before age 17 was there ever a time when your family did not have enough food to eat?); (4) Poor family economic conditions (When you were a child before age 17, compared to the average family in the same community/village at that time, how was your family’s financial situation?); (5) Loneliness (When you were a child, how often did you feel lonely for not having friends? Is it often, sometimes, not very often or never?).
All the ELA exposure were dichotomized into 2 categories, whether she experienced the adversity in childhood or not. Furthermore, we created threat-related and deprivation-related ELA composites by summing the total number of threat and deprivation experiences respectively and classified them as 0, 1, 2, ≥ 3 for analysis.
The outcome of interest in the present study is edentulism collected in the waves of 2013, 2015 and 2018. Edentulism was measured through respondent’s report on the core question, “Have you lost all your upper and lower natural permanent teeth?” (1 = yes; 0 = no) .
Models were adjusted for age at the wave of 2018, baseline hukou residence (1 = rural, 2 = urban), baseline education level (1 = less than primary school, 2 = primary school, 3 = middle school, 4 = equal to or more than high school), marital status at the wave of 2018 (1 = married and lived with the spouse, 2 = widowed; 3 = others), disease history at the wave of 2018 (hypertension, diabetes, dyslipidemia, pulmonary disease, heart disease, kidney disease, disability, and depressive symptoms) and body mass index (BMI), of which BMI was from the physical examination questionnaire in 2015.
Stata 16.0 was used to analyze the data. First, descriptive statistics were calculated for the demographic factors (age, gender, education, hukou residence, and marital status), edentulism, ELA categories, and disease history. Second, bivariate analysis employing Chi-square tests were used to investigate the association between edentulism prevalence and demographic factors as well as various types of ELA exposure. Third, logistic regression analyses were used to calculate the odds ratio and associated 95% confidence intervals (CIs) for various types of ELA exposure in connection to edentulism in males and females individually. We controlled for age, BMI, self-perceived health, education, hukou domicile, marital status, disease history, and threat/deprivation-related ELA in the results shown here. All statistical analyses were performed with a significance threshold of 0.05.