Depressive symptoms among older adults with diabetes mellitus: a cross-sectional study

ABSTRACT BACKGROUND: Diabetes mellitus is a chronic disease with long-term consequences that is often associated with depressive symptoms. This relationship predicts increased morbidity and mortality rates, leading to serious health consequences. OBJECTIVE: To identify the prevalence and health factors associated with depressive symptoms among older adults with diabetes mellitus. DESIGN AND SETTING: An observational cross-sectional study was conducted among 236 older adults in the Basic Healthcare Units of Jequié, Brazil. METHODS: A survey containing sociodemographic, behavioral, and health conditions was used as a data collection instrument, in addition to the Geriatric Depression Scale. The main inclusion criterion was older adults diagnosed with diabetes mellitus. To identify the risk factors associated with depressive symptoms among older adults with diabetes mellitus, logistic regression analysis was conducted for calculating the odds ratio (OR), and a 95% confidence interval (CI) was considered statistically significant. RESULTS: The prevalence of depressive symptoms was 24.2% among older adults with diabetes, corroborating the Brazilian average of 30%. The final multivariate analysis model for the risk of depressive symptoms showed a significant association with diabetes complications [OR = 2.50, 95% CI 1.318–4.74)] and osteoporosis [OR = 2.75, 95% CI 1.285–5.891)]. CONCLUSION: A high prevalence of depressive symptoms was observed among older adults with diabetes. Critically examining older adults with diabetes mellitus is necessary, and screening for depressive symptoms is highly recommended, especially for those with complications resulting from diabetes mellitus and musculoskeletal comorbidities, such as osteoporosis, as it seems to be associated with depressive symptoms.

Therefore, this study is important because, globally, depressive symptoms and diabetes in older adults are becoming the leading causes of disability, with greater frailty and vulnerability.
Thus, the presence of depressive symptoms associated with DM can seriously impact an individual's physical health and quality of life, since both increase their risk for mortality and poor disease management. Furthermore, primary care is the gateway to identifying and monitoring individuals with DM. Thus, this study is relevant to help identify risk factors, establish early interventions, and plan appropriate care for these individuals. Our research questions were: "What is the prevalence of depressive symptoms among older adults with DM?" and "What is the relationship between depressive symptoms and health conditions in older adults?" We hypothesized that a significant proportion of depressive symptoms among older adults with DM would be related to their health status.

OBJECTIVE
This study aimed to identify the prevalence of and health factors associated with depressive symptoms in older adults with DM.

Study design and setting
This cross-sectional study was conducted among 236 older adults

Sample
To compose the sample, the E-SUS Component Individual Care Form was used to group individuals with diabetes aged 60 years or older. This is an online registration form that contains patients' personal information regarding their health problems/conditions and is acquired during individual consultations with primary care professionals. After grouping, a sample of 813 individuals was identified. Adopting a 95% confidence level, 5% error, factor prevalence (i.e., depressive symptomatology) of 30.0 %, 22 and 20% loss replacement rate, a sample of 236 individuals was calculated.
The research was conducted in four BHU areas, containing a total of 91 micro-areas. We conducted a simple random draw from the micro-areas, and the respective community health agent was recruited to help during the home visits and assist the research team in locating the residences. In case of the unavailability or absence of older adults with diabetes in the micro-area, the next micro-area was selected, following the survey for older adults with diabetes until saturation was reached for the number of individuals by BHU.
Inclusion criteria were older adults with DM type 2, aged 60 years or older, and who were enrolled in the BHU area and registered in the Monitoring and Control Service of Hypertension and Diabetes. Exclusion criteria were older adults with cognitive difficulties as established by the Mini-Mental State Examination.

Data collection
For data collection, a form comprising two survey sets was applied, including sociodemographic, behavioral, and health conditions, along with the Geriatric Depression Scale (GDS-15).

Dependent variable
For analysis, depressive symptoms were used as the dependent variable. The Brazilian version of the GDS, abbreviated to 15 items, was used in this study. Regarding the definition of depressive symptoms, scores of ≤ 5 points = negative (absence of depressive symptoms) and ≥ 6 points = positive (presence of depressive symptoms). 23

Independent variables
The sociodemographic variables collected were sex (male and female); age in years tabulated in age groups (60-69, 70-79, and 80 years or older); ethnicity (white, brown, black, and others); marital status (with partner, without partner); and education level divided into two groups (elementary school and above, primary school and below).
The behavioral variables collected were physical activity (yes or no); smoking habits (never smoked, former smoker, and smoker); alcohol habits (non, moderate, excessive consumer); practicing any religion (Catholic, Protestant, and not practicing); and financial difficulty (yes or no).
The health conditions were assessed dichotomously (yes or no), pertaining to family history of diabetes; diabetes complications; rheumatism; osteoporosis; systemic hypertension; circulation problems; heart problems; difficulty sleeping; vision problems; chronic pain; type of DM complications (renal, ocular, circulatory, diabetic foot, and amputation); and prescribed treatment (oral, insulin, non-medicated, none).

Data analysis
Descriptive analysis of population characteristics was performed for all continuous variables (described as mean and standard deviation values) and categorical variables (presented as absolute numbers and percentages). We conducted Chi-square and Fisher's exact tests for categorical variables and Student's t-test for continuous variables. IBM SPSS for Windows statistical package, version 22.0, was used for data analysis (SPSS, Inc., Chicago, Illinois, United States). To test the hypothesis that a significant proportion of depressive symptoms are related to health factors in older adults with DM, the association between depressive symptoms and the possible risk factors among individuals with DM was assessed using Pearson's chi-square test in bivariate analysis. The independent variables with P < 0.2 in the bivariate analysis were entered into a binary logistic regression model using the stepwise regression method. The calculation of the odds ratio (OR) and statistically significant differences (P < 0.05) were considered in the absence of overlapping 95% confidence interval (CI) for all analyses.

RESULTS
The final sample comprised 236 older adults with DM. Most were female (76.7%). The mean age was 71.6 years (± 8.03). Of the sample, 64.0% declared brown ethnicity, 81.4% did not have a partner, and 61.9% received primary or lower education.
Depressive symptoms were reported in 24.2% of older adults with DM. Table 1 shows the characteristics of the study population according to depressive symptoms. Being female without a partner was predominant, although it was not significantly associated with depressive symptoms. Brown ethnicity among older adults was primarily associated with depressive symptoms. Table 2 presents the behavioral characteristics of the study population. Only alcohol consumption was associated with depressive symptoms. Table 3 shows the characteristics of the population's health conditions. The existence of any diabetes complications and ocular and circulatory types of DM complications were significantly associated with depressive symptoms. Among comorbidities, rheumatism, osteoporosis, and heart and circulation problems were associated with depressive symptoms. Difficulty sleeping and severe chronic pain were predominant among those with depressive symptoms and were significantly associated with depressive symptoms. The final multivariate analysis model is presented in Figure 1, which shows the 95% confidence indices of each variable that remained in the model as well as the OR. Notably, the 95% CI coefficients were attenuated; however, DM complication along with osteoporosis remained associated with depressive symptoms.   [30][31][32] As noted, there is strong evidence that these comorbidities are linked with disability and loss of years of life. 33 Notably, people with diabetes and symptoms of depression have higher levels of diastolic blood pressure, triglycerides, glycated hemoglobin, higher body mass index, and worse glycemic control. Therefore, older adults are considered at risk for DM complications and other comorbidities that can significantly compromise their health and quality of life. 19,20 Moreover, depressive symptoms may appear even before the diagnosis of DM or during the onset of complications, depending on the individual or the course of the disease. 34,35 Among the health comorbidities evaluated in this study, osteoporosis remained in the final model even after adjustment, showing an increased risk for depressive symptoms in older adults with DM. This comorbidity is predominantly cited by older adults in aging studies, 7,36 including being associated with diabetes itself. 37,38 The presence of osteoporosis combined with connective tissue problems, neuropathies, and vasculopathies may increase the incidence of complications in older adults with diabetes. This further contributes to their limitations and restricted autonomy, functional disability, fragility, and the potential development of depressive symptoms. 39,40 Osteoporosis commonly causes pain, which directly affects the quality of life of older adults with diabetes. Furthermore, complementary data in this study showed that 77.2% of older adults with depressive symptoms had self-reported chronic pain. Whether this pain is linked to musculoskeletal pain or complications of DM, it remains a primary reason for older adults to seek health services. 37,41,42 Thus, this study expands the knowledge that the presence of osteoporosis and diabetes complications in older adults can be associated with depressive symptoms. Moreover, when