2.1 Ethical considerations
Between June 1, to December 28, 2021. A cross-sectional study using questionnaires was performed among older persons with OP from the outpatient department of West China Hospital. Convenience sampling was used in the study. The Ethics Committee of West China Hospital of Sichuan University approved this research. Informed consent was obtained from all participants. Survey data were anonymously coded to ensure that all identifying information remained confidential.
2.2 Study population
All study participants were measured for bone mineral density (BMD) by dual-energy X-ray absorptiometry (DEXA), and OP diagnoses were consistent with the Chinese guidelines for the diagnosis and treatment of senile OP (2018 edition) [23]. It is a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DEXA). devices are the most commonly used diagnostic method for OP, and the findings are usually expressed by a T-Score: T ≥ -1.0 is normal; -2.5< T < -1.0 is low bone; T ≤ -2.5 is OP; and severe OP is T ≤ -2.5 with fragility fracture [23]. The inclusion criteria were as follows: age ≥ 60 years, diagnosis of OP, and informed and voluntary willingness to participate in the survey. The exclusion criteria were as follows: cognitive disorder, malignant disease, thyroid, parathyroid or adrenal gland disease, corticosteroid use, hormone use, and a history of depression.
2.3 Data collection
For data collection, the number of samples is typically 10 times the number of independent variables in studies that investigate a correlation between 2 variables or multivariate variables [24]. In this study, a multivariate analysis was chosen to assess the relationship of 17 independent variables. Therefore, the minimum required sample size was at least 170. Each participant completed three questionnaires: a questionnaire assessing demographic data, the Self-rating Depression Scale (SDS), and the Physical Activity Scale for the Elderly (PASE). Members of the research team interviewed each participant in the outpatient department of West China Hospital of Sichuan University. The investigator explained the purpose and significance of the study, provided the relevant instructions, and obtained a signed consent form from the participants before administering the survey. The researchers gave the participants a paper questionnaire, which the respondents completed. The researchers immediately collected the questionnaires on the spot.
A database was built using EpiData 3.1 software (EpiData–Comprehensive Data Management and Basic Statistical Analysis System, EpiData Association, Odense, Denmark), and then, the data were double-checked. Incomplete questionnaires were deleted.
2.4 Measures
Depression was assessed using Zung's SDS [25]. The Chinese version of Cronbach's α was 0.784 [26]. The SDS is composed of 20 items and assesses the frequency of symptoms in the past week using a 4-point Likert scale: none of the time or rarely, some of the time, a good part of the time, most or all of the time. In the 20 items, there are 10 positive and 10 negative items, which are assigned a score of 1, 2, 3, 4 or 4, 3, 2, 1, respectively. The 20 item scores are added to obtain the original scores, which are multiplied by 1.25 to calculate the standard score. Higher scores indicate worse depression. In this study, depression scores were classified as follows: without depression, < 50, and with depression, ≥ 50 [27].
The PASE was used to assess the PA of the participants. The PASE was developed by Washburn et al. [28]. The test-retest reliability assessed over a 3-7 weeks interval was 0.75 [28]. The questionnaire includes 12 items focusing on 3 domains of activity, leisure, household, and work-related over the past 7 days. Leisure PA includes walking outside: light, moderate, and strenuous sports; and activities aimed at muscle strength or endurance exercise. Respond “never”, “seldom”, “sometimes”, or “often”. The type of activity performed and the average time spent on that activity each day were recorded. Household PA includes light housework, heavy housework, home repairs, lawn work or yard care, outdoor gardening, and taking care of others that use a “yes” or “no” response format. Work-related PA includes work for pay or as a volunteer and the hours of work involved. PASE scores are from weights and frequency values for each of 12 types of activity. The calculation is performed by multiplying the amount of time spent and participation by the PASE weight value and then summing each contribution for a total score. The total score ranges from 0 to 400 or more. The higher the score is, the stronger the PA [29].
2.5 Covariates
According to the results of the survey, the demographic data were classified into the following categories: age group (60-74, ≥ 75); gender (male, female); marital status (married, divorced, or widowed); education (primary school and below, junior high school, high school, college and above); past occupation (manual labor, intellectual labor); cohabitation status (alone or nursing home, cohabitation with spouse, cohabitation with child); income (pension or social security, child support, others).
Health situation factors were measured as follows. BMI was obtained as the weight (kg) divided by the square of the height (m). We categorized BMI into four groups: underweight, BMI < 18.5 kg/m2; normal weight, BMI 18.5-23.9 kg/m2; overweight, BMI 24-27.9 kg/m2; and obesity, BMI ≥ 28 kg/m2 [30]. Other factors included smoking history (no or yes); drinking history (no or yes); pain (no or yes); and history of fracture (no or yes). Comorbidity was defined as the presence of ≥ 2 conditions (no or yes). Polypharmacy was defined as simultaneously taking ≥ 5 medications (no or yes). Participation in social activities was categorized as no, 1-2 times/year, 1-2 times/month, or 1-2 times/week. The modified Barthel index (MBI) was used to assess activities of daily living (ADL). ADL includes feeding, dressing, grooming, bathing, bowel and bladder control, toilet use, transfer, mobility, and climbing stairs. The total score ranges from 0 to 100, with lower scores indicating worse ADL impairment. We divided ADL into four statuses: no impairment = 100; mild impairment = 61-99; moderate impairment = 41-60; and severe impairment = 0-40 [31, 32]. The frailty phenotype scale was used to assess frailty by Fried et al. [33], which includes five aspects: weight loss, self-reported exhaustion, slow walking speed, weakness, and low PA. Each aspect is assigned 0-1 points, with a range of 0-5 points: nonfrail=1, prefrail=2, frail=3 [33].
2.6 Statistical Analysis
SPSS software (Version 20.0. IBM Inc, Armonk, NY) was used for statistical analyses. Categorical data are presented as frequencies and percentages. Continuous data conforming to a normal distribution are presented as the means and standard deviations, and T test or ANOVA were used for comparisons between groups. Continuous data that did not conform to a normal distribution are represented by median and quartile spacing, and nonparametric tests were used for comparisons between groups. Multivariate logistic regression was used to analyze the influencing factors of depression. With or without depression was the dependent variable, and the independent variable was the variable (P < 0.2) of univariate analysis demographic data (age, sex, marital status, education, past occupation, cohabitation status, income, BMI, smoking history, drinking history, pain, history of fracture, comorbidity, polypharmacy, participation in social activities, ADLs, and frailty status) and PA scores. Multivariate linear regression was used to analyze the influencing factors of PA. PA scores were the dependent variable, and considering the interference factors, the independent variable was the variable (P < 0.2) of univariate analysis demographic data (age, sex, marital status, education, past occupation, cohabitation status, income, BMI, smoking history, drinking history, pain, history of fracture, comorbidity, polypharmacy, participation in social activities, ADLs, frailty status and depression). The correlation between depression and PA was analyzed. Pearson correlation analysis was used if the data followed a normal distribution, and Spearman correlation analysis was used if the data did not follow a normal distribution. A p value < 0.05 was considered statistically significant.