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Social Support and Depression Related to Older Adults’ Hypertension Control in Rural China
Am J of Geriatric Psychiatry 27:11 (2019) 1268−1276
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.ajgponline.org
Regular Research Article
Social Support and Depression Related to Older Adults’ Hypertension Control in Rural China Tingfei Zhu, B.S., Jiang Xue, B.S., Shulin Chen, M.D., Ph.D. ARTICLE INFO
ABSTRACT
Article history: Received January, 21 2019 Revised April, 24 2019 Accepted April, 24 2019
Objective: This study aimed to investigate association between social support and hypertension (HTN) control in rural China older adults, and to what extent depression mediates this relationship. The authors hypothesized that depression severity mediated the relationship between social support and HTN control. Methods: Data for the analyses were obtained from baseline data from a randomized controlled clinical trial of a collaborative depression care management intervention conducted in rural villages of China, with older adults with comorbid depression and HTN. Data included baseline assessments of 2,351 subjects aged 60 years and older, whose blood pressure and depression severity were measured using a calibrated manual sphygmomanometer and the 17-item Hamilton Depression Rating Scale (HDRS-17), respectively. Social support was measured using the 20-item Medical Outcomes Study−Social Support Survey. Results: Uncontrolled HTN was associated with older age (t[df = 2349] = 3.16; p < 0.01), higher HDRS-17 score (t[df = 1488] = 5.89; p < 0.001), and lower social support (t[df = 2349] = 5.37; p < 0.001). A significant indirect effect of social support via depression severity in relation to HTN control (a £ b = −0.04[0.01]), bootstrap p = 0.0015, and 95% confidence interval (−0.07, −0.02), accounting for 11% of the effect of social support on HTN control. Conclusion: These findings imply that social support impacts HTN control directly and indirectly through depression. Intervention approaches such as primary care-based collaborative care models should address social support to achieve greater outcomes for depression and HTN management. (Am J Geriatr Psychiatry 2019; 27:1268−1276)
Key Words: Depression hypertension older adults social support
From the Department of Psychology and Behavior Sciences, Zhejiang University, Hangzhou, Zhejiang, China. Send correspondence and reprint requests to Shulin Chen, M.D., Ph.D., Department of Psychology and Behavior Sciences, Zhejiang University, No. 148 Tianmushan Rd., Xixi Campus of Zhejiang University, Hangzhou, Zhejiang 310028, China. e-mail: [email protected] © 2019 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.jagp.2019.04.014
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INTRODUCTION
H
ypertension (HTN) is one of the most common chronic diseases worldwide, contributing to two-thirds of all strokes and half of all coronary disease, and thus representing as a major risk factor for cardiovascular morbidity and mortality.1−3 Onequarter of the world’s adult population exhibits HTN, and HTN prevalence is estimated to reach 29% by 2025.4 Almost 75% of people with HTN live in developing countries, where people have limited health resources, low awareness about HTN prevention, and consequently poor blood pressure (BP) control.5 In China, 27.8% of the adult population suffered from HTN in 2014,6 and HTN prevalence may be reaching more than 40% of the aging population.7−10 However, fewer than one-third of the patients are currently being treated, and less than 8% get their BP controlled.11 Social support is one of the most well-documented psychosocial factors of physical health outcomes,12−14 including HTN.15 Social support is regarded as a buffer against stressors that may affect health through protecting individuals from negative consequences of major illness or stressful situations, and through providing resources that facilitate adaptive coping to illnesses.16−19 Epidemiologic studies indicate that individuals with poor social support have higher mortality rates, especially from cardiovascular diseases.20,21 Additionally, older people with sufficient social support tend to report better BP control and lower incidence of HTN.15,22 Sherbourne and Stewart23 identified four components of social support: 1) emotional/informational support (expression of positive affect, empathetic understanding, and encouragement of expressions of feelings [emotional] and offering of advice, information, guidance, or feedback [informational]); 2) tangible support (provision of material aid or behavioral assistance); 3) positive social interaction (availability to engage in pleasant activities); and 4) affection support (expressions of love and affection). Social support was considered to be a single-dimensional construct in many studies,24,25 rather than a complex, multidimensional construct.26,27 The impact of different types of social support on HTN remains unclear. Most theoretical models for social support and physical health have postulated psychological factors,
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especially depression, as important pathways. This means that social support may impact HTN control directly or indirectly through depression.21,28 Depression is the major cause of disability among patients with chronic diseases, affecting 350 million people worldwide.4,29 Patients with HTN are more likely to develop depression, and depression has been recognized as an independent risk factor for HTN.29,30 In China, 12.8% of the elderly with HTN exhibit clinically significant depressive symptoms, with rates of 5.3% and 32.8% among patients with controlled and uncontrolled HTN, respectively.31 Furthermore, patients with depression display lower adherence to HTN treatment,32 which results in 50% of treatment failures.33,34 The impact of social support on depression severity is also well studied. A recent meta-analysis showed that older people with more social support had lower prevalence of depression (odds ratio: 0.56; 95% confidence interval: [CI] [0.55»0.57]),35 indicating that social support is an important protective factor against depression. Studies also showed that social support was associated with remission of depressive symptoms.36−38 Additionally, Brown et al.37 found that a lack of social support was associated with a greatly increased risk of subsequent depression once a stressor occurred. Finally, subjective social support was found to significantly predict the fluctuation of depressive symptoms in the George et al.36 study. Despite strong evidence of interactions between social support, psychological activities, and physical health, however, decades of studies have failed to provide direct evidence for psychological factors as pathways linking social support with physical health outcomes.39 Therefore, an ongoing study on management of comorbid depression and HTN among older adults in rural Chinese primary care clinics is trying to understand the exact role of depression as a mediator between social support and HTN. This study hypothesizes that the effect of social support on HTN control in older adults is mediated by their depression severity.
METHODS Setting and Participants Data for the analyses were obtained from the baseline assessments of the depression/HTN in Chinese
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Social Support, Depression, Hypertension Older Adults−Collaboration in Health (COACH) Study. The COACH Study is an ongoing project funded by the U.S. National Institute of Mental Health designed to compare the effectiveness of collaborative depression care management with that of usual care for the treatment of comorbid depression and HTN in Chinese older rural village residents.40 The inclusion criteria were: 1) status as community-dwelling resident registered to the selected villages; 2) age 60 years and older; 3) a chart diagnosis of HTN; 4) scores of 10 or more on the Patient Health Questionnaire-9 (PHQ-9); 5) capacity to communicate independently with interviewers; and 6) capacity to give informed consent. Exclusion criteria included: 1) mania, psychosis, or alcohol abuse or dependence active in the past 6 months based on the M.I.N.I. Diagnostic Interview,41 a valid and reliable version of which is widely used in China. Recommendations were issued to the primary care provider (PCP) for psychiatric referral for individuals with acute symptoms. 2) Acute suicide risk. If patients were found to be at high risk for suicide based on the intake assessment, they received immediate intervention through referral by their PCP to the county mental hospital and/or by informing patients’ relatives. Ten towns with a total of 219 villages were included in the COACH study. Their total population aged 60 years and older was 101,318, of whom 29,659 (29%) had a diagnosis of HTN registered in their electronic medical records. None of these elder patients had ever received a diagnosis of depression or depression treatment before. PCPs screened 26,677 (89%) patients with HTN for depressive symptoms using the PHQ-9, and 2,899 patients had a total PHQ-9 score of 10 or more, indicative of clinically significant depression.42 Patients with clinically significant depression were invited to participate in the study. Written informed consent was provided by 2,365 participants, of whom 14 had missing data on relevant measurements. The remaining 2,351, therefore, were included for analyses.
MEASUREMENTS BP The participants’ BP measurements were obtained by their village doctors in their home or village clinics.
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Village doctors used a calibrated manual sphygmomanometer and stethoscope according to standards developed by the Center for Disease Control and Prevention in China (auscultation with cuff deflation method after sitting quietly for 5 minutes in the proper position; no caffeine, exercise, or smoking in preceding 30 minutes; appropriately sized cuff; average of three measurements recorded). The Charlson Comorbidity Index was used to measure the comorbid medical conditions. The BP readings distinguished two HTN conditions: controlled HTN versus uncontrolled HTN. The latter was defined as systolic BP 130 or higher or diastolic BP 80 or higher for patients with diabetes mellitus, coronary heart disease, or renal disease, and systolic BP 140 or higher or diastolic BP 90 or higher for all others.43 Remaining subjects were defined as displaying controlled HTN. Depression, social support, and demographic characteristics The Chinese version of the Hamilton Depression Rating Scale (HDRS), which was shown to display good reliability and validity in Chinese elders,44 was used to measure depressive symptoms. The 20-item Medical Outcomes Study−Social Support Survey (MOS-SSS), which was originally designed to assess social support in a community sample of patients with chronic illness,23 was used to measure social support. The Chinese version of MOS-SSS was shown to display good reliability and validity.45 Demographic characteristics including sex, age, education level, and marital status were collected. Data Analysis Descriptive analyses, the t test, and the x2 test were used to examine the basic characteristics of our sample. The t test was used to explore the difference of social support between uncontrolled HTN and controlled HTN. The Sobel Test46 for mediation analysis was conducted to examine the indirect association of the predictor, social support, via mediator, and depression severity, which was examined in relation to HTN control. The test was performed by using the model 4 of Andrew Hayes’47 PROCESS procedure for SPSS software Version 20 (IBM Corp., Armonk, NY). Using Ordinary Least Squares (OLS) regression-based path analysis, PROCESS covers the estimation of
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Zhu et al. various classes of models which allow indirect and/ or direct effects to be moderated.47 Path coefficients (a, b, c, and c’) representing the linear or logistic regression coefficients for each path in the mediation model were obtained. The a-path represents the association between the predictor (social support) and mediator variables (depression severity). The b-path denotes the relationship between the mediator (depression severity) and outcome variables (HTN control), while controlling for the predictor variable (social support). The c’-path (also called “direct effect”) and the c-path (also known as “total effect”) represent the associations between the predictor and outcome variables including and excluding the mediator variable, respectively.48 A statistically significant difference between c and c’ (c-c’= a £ b, a £ b was also known as “indirect effect”)49 is indication of a mediation effect. The typical 95% CIs were used to determine significance for the indirect effects, in which significance was obtained using bootstrapping with 5,000 resamples.50 Significance of indirect effect would be demonstrated with CIs not including zero.51,52 We used percent mediation as a measure of effect size, a measure of effect size interpreted as the percent of the total effect accounted for by the indirect effect.53,54 We then repeated the earlier mediation
analyses stratified by different components of social support to examine whether mediation effects were present in different components of social support. Age, sex, educational level, marital status, and Charlson Comorbidity Index were used as covariates in all analyses. These demographic factors have been commonly associated with HTN control in the literature.55,56 In the analysis, uncontrolled HTN was coded as 1, whereas controlled HTN was coded as 0. Depression and social support were treated as continuous variables identified by the HDRS-17 and MOS-SSS. All analyses were performed using SPSS software version 20 (IBM, Armonk, NY).
RESULTS Demographic Characteristics Table 1 displays the demographic characteristics of the sample in subgroups of HTN control. The independent-sample t test and the x2 test were used to examine differences in demographics between participants with uncontrolled or controlled HTN. Older patients with uncontrolled HTN had an older mean age and higher HDRS score compared with those
TABLE 1. Demographic Characteristics (N = 2,351) Demographics Characteristics
Controlled HTN
Uncontrolled HTN
Participant, N Female, N (%) Age, mean § SD Education, N (%) 0 years 1−5 years 6−8 years 9−11 years 12 years and more Marital status, N (%) Married Divorced Never married Widowed Formal separation HDRS-17, mean § SD Depression, N (%) Major depression Mild or moderate depression
668 457 (68.4) 73.61 § 8.30
1683 1110 (66.0) 74.79 § 8.18
351 (52.5) 266 (39.8) 42 (6.3) 7 (1.0) 2 (0.3)
937 (55.7) 655 (38.9) 77 (4.6) 10 (0.6) 4 (0.2)
415 (62.1) 3 (0.4) 4 (0.6) 246 (36.8) 0 21.21 § 3.50
977 (58.1) 12 (0.7) 21 (1.2) 671 (39.9) 2 (0.1) 22.21 § 4.28
137 (20.5) 531 (79.5)
419 (24.9) 1264 (75.1)
df
t/x2
1 2,349 4
1.30 3.16b 5.45
4
5.00
1,488
5.89c
1
5.10a
Notes: Major depression = HDRS more than 24; mild or moderate depression = HDRS 24 or less. SD: standard deviation. a Statistically significant at p < 0.05. b Statistically significant at p < 0.01. c Statistically significant at p < 0.001.
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Social Support, Depression, Hypertension its dimensions (emotional/informational support, tangible support, positive social interaction, and affection support) were significantly different in patients with controlled and uncontrolled HTN (Table 2).
with controlled HTN (Table 1). No difference was found in sex, education, and marital status (Table 1).
Association Between Social Support and HTN Control Mediation of Depression Severity
Table 2 illustrates difference in social support as well as its five components among subgroups of HTN control. The t test was used to explore the difference of social support between uncontrolled HTN and controlled HTN. The mean score of the full MOS-SSS and
Table 3 illustrates the mediation of depression severity. Increased depression severity was significantly associated with more social support and worse HTN control (Table 3). Higher MOS-SSS
TABLE 2. Independent-Sample Test on Social Support and HTN Control
MOS-SSS Emotional/informational support Tangible support Positive social interaction Affection support
Controlled HTN (N = 668) Mean § SD
Uncontrolled HTN (N = 1,683) Mean § SD
MD
df
ta
3.16 § 0.64 2.94 § 0.72 3.99 § 0.72 2.90 § 0.83 3.02 § 0.81
3.01 § 0.61 2.81 § 0.69 3.85 § 0.75 2.72 § 0.79 2.80 § 0.77
0.15 0.12 0.14 0.18 0.21
2,349 2,349 2,349 2,349 2,349
5.37 3.84 4.14 4.86 5.91
Notes: MD: Mean difference; SD: standard deviation. a Statistically significant at p < 0.001.
TABLE 3. Depression Severity Mediates the Association Between Social Support and HTN Control, with Age, Sex, Educational Level, Marital Status, and Charlson Comorbidity Index as Covariates (N = 2,351) Path a MOS-SSS
Emotional/informational support
Tangible support
Positive social interaction
Affection support
b t/Za df p b t/Z df p b t/Z df p b t/Z df p b t/Z df p
−0.84 −5.87 2326 <0.0001 −0.67 −5.04 2,326 <0.0001 −0.56 −4.81 2,326 <0.0001 −0.37 −3.61 2,326 0.0003 −0.65 −5.91 2,326 <0.0001
Path b 0.05 3.83 1 0.0001 0.05 4.00 1 0.0001 0.05 4.10 1 <0.0001 0.05 4.03 1 0.0001 0.05 3.71 1 0.0002
Path c
Path c’
−0.35 −4.44 1 <0.0001 −0.23 −3.38 1 0.0007 −0.16 −2.44 1 0.0148 −0.24 −4.04 1 0.0001 −0.33 −5.38 1 <0.0001
−0.31 −3.95 1 0.0001 −0.21 −2.95 1 0.0032 −0.14 −2.02 1 0.0439 −0.23 −3.72 1 0.0002 −0.30 −4.89 1 <0.0001
a £ b, 95% Bootstrapped CI for a £ b; p
Percent Mediation (PM)
−0.04 [−0.07, −0.02]; p = 0.0015
0.11
−0.03 [−0.06, −0.02]; p = 0.002
0.13
−0.03 [−0.05, −0.01]; p = 0.0021
0.18
−0.02 [−0.04, −0.01]; p = 0.0082
0.08
−0.03 [−0.05, −0.01]; p = 0.0018
0.09
Notes: The a-path represents the association between social support and depression severity. The b-path denotes the relationship between depression severity and HTN control, while also controlling for social support. The c-path and the c’-path represent the associations between social support and HTN control without and with depression severity included as a mediator, respectively. Age, sex, educational level, marital status, and Charlson Comorbidity Index used as covariates in all analyses. As a £ b = c − c’, the 95% CI for a £ b indicates that a significant medication has occurred when it does not include 0 and the c’ path is no longer significant. Percent mediation (PM) is a measure of effect size computed as (a £ b)/(c’+ a £ b). a T statistics for continuous variables and z statistics for binary variables.
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Zhu et al. scores correlated with worse HTN control, and this association became significant after controlling for depression severity (Table 3). There was a significant indirect effect on HTN control by social support through increased depression severity (a £ b = −0.04 [0.01]; bootstrap p = 0.0015; 95% CI: [−0.07, −0.02]). The mediator accounted for approximately 11% of the total effect (Table 3). Stratified analyses by different components of social support revealed significant mediation effects. For emotional/ informational support (a £ b = −0.03 [0.01]; bootstrap p = 0.002; 95% CI: [−0.06, ¡0.02]) with depression severity accounting for 13% of the total effect (Table 3). For tangible support (a £ b = −0.03 [0.01]; bootstrap p = 0.0021; 95% CI: [−0.05, ¡0.01]) with depression severity accounting for 18% of the total effect (Table 3). For positive social interaction (a £ b = −0.02 [0.01]; bootstrap p = 0.0082; 95% CI: [−0.04, ¡0.01]) with depression severity accounting for 8% of the total effect (Table 3). For affection support (a £ b = −0.03 [0.01]; bootstrap p = 0.0018; 95% CI: [−0.05, ¡0.01]) with depression severity accounting for 9% of the total effect (Table 3). Given the earlier-mentioned results, a partial mediation effect of depression severity in social support and HTN control existed. Consistent with the hypothesis, the results manifested that depression severity partially mediated the relationship between social support and HTN control. Different types of social support had differing impacts on HTN (Table 3).
DISCUSSION There is strong evidence linking social support to health outcomes, with a psychological factor generally considered as a potential pathway for both theoretical and applied reasons. However, the available recent literature provides no statistical evidence for this association. To the best of our knowledge, the present study is the first attempt to investigate the relationship between social support and HTN control in the Chinese aging population with an emphasis on role of depression severity within the association. Main findings show that older patients with poor social support are more likely to exhibit uncontrolled BP, an association that depression severity partially mediates. The finding that poor social support is significantly associated with higher risk of uncontrolled HTN is
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consistent with results of previous studies.15 Theoretically, social support is supposed to act as a buffer against stressors that are deleterious to health, protect individuals from some of the negative consequences of illnesses, and provide resources that facilitate adaptive coping in response to the illness.16−19 In these procedures, psychological responses are generally considered to play an important role. The unique contribution of this study lies in the finding that depression severity partially mediates the effect of social support on HTN control. That is, older people with poorer social support are at higher risk of developing depression and facing aggravated depression in the long run, which may in turn contribute to insufficient treatment of HTN.32 Specially, previous studies have revealed that patients with depression have lower adherence to the HTN treatment,32 which results in 50% of treatment failures.33,34 An important implication of this mediation effect is the medical priority of treating depression in older patients with HTN, or other chronic conditions. Indeed, the fact that chronic diseases are usually accompanied by mental disorders such as depression has been well recognized in recent research. There is also robust evidence that these comorbid mental disorders may adversely affect chronic disease care by, for instance, decreasing adherence to treatment;32 leading to higher functional impairment;57 increasing risk of complications and mortality;58 and increasing medical costs.59 In response to the increasing burden of mental disorders and frequent comorbidity with chronic illnesses, international calls focus on the integration of mental health interventions into existing primary care system. This would help reduce the burden of disease and disability associated with mental disorders, while simultaneously helping to achieve the desired outcomes for health conditions.60 Consistent with these initiatives, the present study supports and underlines the need of integrating depression and HTN care in Chinese primary care settings. Promising approaches toward this goal, which have been developed and well tested in Western nations, are primary care-based collaborative care models. Testing the effectiveness of these models is the objective of the COACH study. However, because mediation by depression is partial, even with depression treatment in patients with HTN, poor social support may still lead to poor HTN control. This finding emphasizes the importance of providing social support throughout depression and
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Social Support, Depression, Hypertension HTN management. In a collaborative care model that manages depression and HTN, resources of social support, such as the role of aging workers (social workers [SWs]) in the COACH study,41 should be integrated. Given that all four dimensions of support social were demonstrated to be highly related to HTN control, SWs were therefore trained to take corresponding measures regarding these aspects. For example, to provide emotional support and affection support, SWs were encouraged to listen to their clients seriously and patiently. To provide informational support, SWs could also improve the communications regarding disease and treatment between patients and PCPs and organize community-based education for patients and their families, so that they can better understand the diseases and treatment. Finally, other activities such as nutrition management and weekly visits to patients’ home provided tangible support and positive social interaction. Limitations for this study exist. First, the study sample lives in rural Zhejiang Province; therefore, the findings may not be generalizable to populations from urban areas or other developed countries. However, because depression and poor social support are common issues worldwide, findings may still lend insights to HTN management in a wide range of cultures and primary care settings. Second, the focus of this study was solely on older adults with depression and HTN, a group at very high risk for both poor social support and BP control. Nonetheless, the issue of social support likely applies to older adults with depression and any chronic condition. Future studies are recommended to examine these associations. Third, we used no diagnostic assessment of depression. Both categorical diagnosis and symptom severity of depression are important to consider in their relationships to HTN. Nonetheless, the PHQ-9 is a valid and effective measure of depressive symptom severity that is highly correlated with the diagnosis of major affective illness by the cutoff of 10 or more.
In addition, the HDRS, which was shown to display good reliability and validity in Chinese elders, was used to measure depressive symptoms. A more complete diagnostic assessment of depression should be included in further research. Fourth, the lack of measurement of related factors like antihypertensive treatments, under-prescribing, nonadherence, poor medical follow up, diet, exercise, weight, and financial resources and other related factors were limitations in understanding the relationships of interest. Antidepressant medications can influence BP, and the results of the PHQ-9 could be influenced by the use of those drugs. We acknowledge that antihypertensive treatments and other factors are closely related to HTN control. Further studies are necessary to fill these blank. Finally, the data of this study are cross-sectional, which prevented analysis of the longitudinal associations between social support, depression, and HTN. Therefore, further experimental or longitudinal studies are necessary to facilitate an evaluation of causality.
CONCLUSIONS Social support is significantly related to HTN control of older patients with depression in China, and depression severity partially mediates the association. Primary care-based collaborative care models are recommended to manage both depression and HTN in older Chinese adults. Finally, SWs should be integrated in those models to provide social support and better health outcomes. The authors thank research assistants (Yuxing Jiang, Jiayu Wang, Wenqi Weng, Xinlai Zhao, et al.) for their efforts in the data collection. This work was supported by the National Institutes of Health (grant number R01MH100298). Tingfei Zhu and Jiang Xue and co−first authors.
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27. Sanchez-Martinez M, Lopez-Garcia E, Guallar-Castillon P, et al: Social support and ambulatory blood pressure in older people. J Hypertens 2016; 34:2045–2052 28. Uchino BN: Social Support and Physical Health: Understanding the Health Consequences of Relationships. New Haven, CT, Yale University Press, 2004 29. Davidson K, Jonas BS, Dixon KE, et al: Do depression symptoms predict early hypertension incidence in young adults in the CARDIA study? Coronary artery risk development in young adults. Arch Intern Med 2000; 160:1495–1500 30. Meurs M, Groenewold NA, Roest AM, et al: The associations of depression and hypertension with brain volumes: independent or interactive? Neuroimage Clin 2015; 8:79–86 31. Xue J, Chen S, Bogner HR, et al: The prevalence of depressive symptoms among older patients with hypertension in rural China. Int J Geriatr Psychiatry 2017; 32:1411–1417 32. Krouselwood MA, Frohlich ED: Hypertension and depression: coexisting barriers to medication adherence. J Clin Hypertens 2010; 12:481–486 33. Stephenson J: Noncompliance may cause half of antihypertensive drug failures. JAMA 1999; 282:313 34. Naderi SH, Bestwick JP, Wald DS: Adherence to drugs that prevent cardiovascular disease: meta-analysis on 376,162 patients. Am J Med 2012; 125: 882−887.e1 35. Genevieve G, Honkaniemi H, Quesnel-Vallee A: Social support and protection from depression: systematic review of current findings in Western countries. Br J Psychiatry 2016; 209:284–293 36. George LK, Blazer DG, Hughes DC, et al: Social support and the outcome of major depression. Br J Psychiatry 1989; 154:478–485 37. Brown GW, Andrews B, Harris T, et al: Social support, selfesteem and depression. Psychol Med 1986; 16:813–831 38. Liu RT, Hernandez EM, Trout ZM, et al: Depression, social support, and long-term risk for coronary heart disease in a 13-year longitudinal epidemiological study. Psychiatry Res 2017; 251:36 39. Uchino BN, Bowen K, Carlisle M, et al: Psychological pathways linking social support to health outcomes: a visit with the “ghosts” of research past, present, and future. Soc Sci Med 2012; 74:949–957 40. Chen S, Conwell Y, Xue J, et al: Protocol of an ongoing randomized controlled trial of care management for comorbid depression and hypertension: the Chinese Older Adult Collaborations in Health (COACH) study. BMC Geriatr 2018; 18:124 41. Sheehan DV, Lecrubier Y, Sheehan KH, et al: The Mini-International Neuropsychiatric Interview (M.I.N.I.): the development and validation of a structured diagnostic psychiatric interview for DSM-IV and ICD-10. J Clin Psychiatry 1998;59 (suppl 20):22–33 42. Chen S, Chiu H, Xu B, et al: Reliability and validity of the PHQ−9 for screening late-life depression in Chinese primary care. Int J Geriatr Psychiatry 2010; 25:1127–1133 43. Chobanian AV, Bakris GL, Black HR, et al: Seventh report of the joint national committee on prevention, detection, evaluation, and treatment of high blood pressure. Hypertension 2003; 42:1206–1252 44. Zhang MY: Handbook of Rating Scales in Psychiatry. Changsha: Hunan Science and Technology Press, 1998 45. Wang W, Zheng X, He HG, et al: Psychometric testing of the Chinese Mandarin version of the Medical Outcomes Study Social Support Survey in patients with coronary heart disease in mainland China. Qual Life Res 2013; 22:1965–1971
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Social Support, Depression, Hypertension 46. Sobel ME: Asymptotic confidence intervals for indirect effects in structural equation models. Sociol Methodol 1982; 13:290–312 47. Hayes AF: Introduction to mediation, moderation, and conditional process analysis: a regression-based approach. J Educ Meas 2013; 51:335–337 48. Funes CM, Lavretsky H, Ercoli L, et al: Apathy mediates cognitive difficulties in geriatric depression. Am J Geriatr Psychiatry 2018; 26:100–106 49. Mackinnon DP, Warsi G, Dwyer JH: A simulation study of mediated effect measures. Multivariate Behav Res 1995; 30:41 50. Hesterberg T: Bootstrap, 3. Hoboken, NJ: WIREs Comp Stat, 2011. p. 497–526 51. Preacher KJ, Hayes AF: Asymptotic and resampling strategies for assessing and comparing indirect effects in multiple mediator models. Behav Res Methods 2008; 40:879–891 52. Preacher KJ, Hayes AF: SPSS and SAS procedures for estimating indirect effects in simple mediation models. Behav Res Methods Instrum Comput 2004; 36:717–731 53. Alwin DF, Hauser RM: The decomposition of effects in path analysis. Am Sociol Rev 1975; 40:37–47
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54. Zhonglin W, Xitao F: Monotonicity of effect sizes: questioning kappa-squared as mediation effect size measure. Psychol Methods 2015; 20:193–203 55. Ford ES, Cooper RS: Risk factors for hypertension in a national cohort study. Hypertension 1991; 18:598–606 56. Abusaad K, Chetrit A, Eilatadar S, et al: Blood pressure level and hypertension awareness and control differ by marital status, sex, and ethnicity: a population-based study. J Membr Biol 2012; 65: m970 57. Von KM, Katon W, Lin EH, et al: Potentially modifiable factors associated with disability among people with diabetes. Psychosom Med 2005; 67:233–240 58. Thorpe KE, Ogden LL, Galactionova K: Chronic conditions account for rise in Medicare spending from 1987 to 2006. Health Aff 2010; 29:718–724 59. Simon GE, Katon WJ, Lin EH, et al: Diabetes complications and depression as predictors of health service costs. Gen Hosp Psychiatry 2005; 27:344 60. Collins PY, Insel TR, Chockalingam A, et al: Grand challenges in global mental health: integration in research, policy, and practice. PLoS Med 2013; 10:e1001434
Am J Geriatr Psychiatry 27:11, November 2019
Available online at www.sciencedirect.com
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Regular Research Article
Social Support and Depression Related to Older Adults’ Hypertension Control in Rural China Tingfei Zhu, B.S., Jiang Xue, B.S., Shulin Chen, M.D., Ph.D. ARTICLE INFO
ABSTRACT
Article history: Received January, 21 2019 Revised April, 24 2019 Accepted April, 24 2019
Objective: This study aimed to investigate association between social support and hypertension (HTN) control in rural China older adults, and to what extent depression mediates this relationship. The authors hypothesized that depression severity mediated the relationship between social support and HTN control. Methods: Data for the analyses were obtained from baseline data from a randomized controlled clinical trial of a collaborative depression care management intervention conducted in rural villages of China, with older adults with comorbid depression and HTN. Data included baseline assessments of 2,351 subjects aged 60 years and older, whose blood pressure and depression severity were measured using a calibrated manual sphygmomanometer and the 17-item Hamilton Depression Rating Scale (HDRS-17), respectively. Social support was measured using the 20-item Medical Outcomes Study−Social Support Survey. Results: Uncontrolled HTN was associated with older age (t[df = 2349] = 3.16; p < 0.01), higher HDRS-17 score (t[df = 1488] = 5.89; p < 0.001), and lower social support (t[df = 2349] = 5.37; p < 0.001). A significant indirect effect of social support via depression severity in relation to HTN control (a £ b = −0.04[0.01]), bootstrap p = 0.0015, and 95% confidence interval (−0.07, −0.02), accounting for 11% of the effect of social support on HTN control. Conclusion: These findings imply that social support impacts HTN control directly and indirectly through depression. Intervention approaches such as primary care-based collaborative care models should address social support to achieve greater outcomes for depression and HTN management. (Am J Geriatr Psychiatry 2019; 27:1268−1276)
Key Words: Depression hypertension older adults social support
From the Department of Psychology and Behavior Sciences, Zhejiang University, Hangzhou, Zhejiang, China. Send correspondence and reprint requests to Shulin Chen, M.D., Ph.D., Department of Psychology and Behavior Sciences, Zhejiang University, No. 148 Tianmushan Rd., Xixi Campus of Zhejiang University, Hangzhou, Zhejiang 310028, China. e-mail: [email protected] © 2019 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.jagp.2019.04.014
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INTRODUCTION
H
ypertension (HTN) is one of the most common chronic diseases worldwide, contributing to two-thirds of all strokes and half of all coronary disease, and thus representing as a major risk factor for cardiovascular morbidity and mortality.1−3 Onequarter of the world’s adult population exhibits HTN, and HTN prevalence is estimated to reach 29% by 2025.4 Almost 75% of people with HTN live in developing countries, where people have limited health resources, low awareness about HTN prevention, and consequently poor blood pressure (BP) control.5 In China, 27.8% of the adult population suffered from HTN in 2014,6 and HTN prevalence may be reaching more than 40% of the aging population.7−10 However, fewer than one-third of the patients are currently being treated, and less than 8% get their BP controlled.11 Social support is one of the most well-documented psychosocial factors of physical health outcomes,12−14 including HTN.15 Social support is regarded as a buffer against stressors that may affect health through protecting individuals from negative consequences of major illness or stressful situations, and through providing resources that facilitate adaptive coping to illnesses.16−19 Epidemiologic studies indicate that individuals with poor social support have higher mortality rates, especially from cardiovascular diseases.20,21 Additionally, older people with sufficient social support tend to report better BP control and lower incidence of HTN.15,22 Sherbourne and Stewart23 identified four components of social support: 1) emotional/informational support (expression of positive affect, empathetic understanding, and encouragement of expressions of feelings [emotional] and offering of advice, information, guidance, or feedback [informational]); 2) tangible support (provision of material aid or behavioral assistance); 3) positive social interaction (availability to engage in pleasant activities); and 4) affection support (expressions of love and affection). Social support was considered to be a single-dimensional construct in many studies,24,25 rather than a complex, multidimensional construct.26,27 The impact of different types of social support on HTN remains unclear. Most theoretical models for social support and physical health have postulated psychological factors,
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especially depression, as important pathways. This means that social support may impact HTN control directly or indirectly through depression.21,28 Depression is the major cause of disability among patients with chronic diseases, affecting 350 million people worldwide.4,29 Patients with HTN are more likely to develop depression, and depression has been recognized as an independent risk factor for HTN.29,30 In China, 12.8% of the elderly with HTN exhibit clinically significant depressive symptoms, with rates of 5.3% and 32.8% among patients with controlled and uncontrolled HTN, respectively.31 Furthermore, patients with depression display lower adherence to HTN treatment,32 which results in 50% of treatment failures.33,34 The impact of social support on depression severity is also well studied. A recent meta-analysis showed that older people with more social support had lower prevalence of depression (odds ratio: 0.56; 95% confidence interval: [CI] [0.55»0.57]),35 indicating that social support is an important protective factor against depression. Studies also showed that social support was associated with remission of depressive symptoms.36−38 Additionally, Brown et al.37 found that a lack of social support was associated with a greatly increased risk of subsequent depression once a stressor occurred. Finally, subjective social support was found to significantly predict the fluctuation of depressive symptoms in the George et al.36 study. Despite strong evidence of interactions between social support, psychological activities, and physical health, however, decades of studies have failed to provide direct evidence for psychological factors as pathways linking social support with physical health outcomes.39 Therefore, an ongoing study on management of comorbid depression and HTN among older adults in rural Chinese primary care clinics is trying to understand the exact role of depression as a mediator between social support and HTN. This study hypothesizes that the effect of social support on HTN control in older adults is mediated by their depression severity.
METHODS Setting and Participants Data for the analyses were obtained from the baseline assessments of the depression/HTN in Chinese
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Social Support, Depression, Hypertension Older Adults−Collaboration in Health (COACH) Study. The COACH Study is an ongoing project funded by the U.S. National Institute of Mental Health designed to compare the effectiveness of collaborative depression care management with that of usual care for the treatment of comorbid depression and HTN in Chinese older rural village residents.40 The inclusion criteria were: 1) status as community-dwelling resident registered to the selected villages; 2) age 60 years and older; 3) a chart diagnosis of HTN; 4) scores of 10 or more on the Patient Health Questionnaire-9 (PHQ-9); 5) capacity to communicate independently with interviewers; and 6) capacity to give informed consent. Exclusion criteria included: 1) mania, psychosis, or alcohol abuse or dependence active in the past 6 months based on the M.I.N.I. Diagnostic Interview,41 a valid and reliable version of which is widely used in China. Recommendations were issued to the primary care provider (PCP) for psychiatric referral for individuals with acute symptoms. 2) Acute suicide risk. If patients were found to be at high risk for suicide based on the intake assessment, they received immediate intervention through referral by their PCP to the county mental hospital and/or by informing patients’ relatives. Ten towns with a total of 219 villages were included in the COACH study. Their total population aged 60 years and older was 101,318, of whom 29,659 (29%) had a diagnosis of HTN registered in their electronic medical records. None of these elder patients had ever received a diagnosis of depression or depression treatment before. PCPs screened 26,677 (89%) patients with HTN for depressive symptoms using the PHQ-9, and 2,899 patients had a total PHQ-9 score of 10 or more, indicative of clinically significant depression.42 Patients with clinically significant depression were invited to participate in the study. Written informed consent was provided by 2,365 participants, of whom 14 had missing data on relevant measurements. The remaining 2,351, therefore, were included for analyses.
MEASUREMENTS BP The participants’ BP measurements were obtained by their village doctors in their home or village clinics.
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Village doctors used a calibrated manual sphygmomanometer and stethoscope according to standards developed by the Center for Disease Control and Prevention in China (auscultation with cuff deflation method after sitting quietly for 5 minutes in the proper position; no caffeine, exercise, or smoking in preceding 30 minutes; appropriately sized cuff; average of three measurements recorded). The Charlson Comorbidity Index was used to measure the comorbid medical conditions. The BP readings distinguished two HTN conditions: controlled HTN versus uncontrolled HTN. The latter was defined as systolic BP 130 or higher or diastolic BP 80 or higher for patients with diabetes mellitus, coronary heart disease, or renal disease, and systolic BP 140 or higher or diastolic BP 90 or higher for all others.43 Remaining subjects were defined as displaying controlled HTN. Depression, social support, and demographic characteristics The Chinese version of the Hamilton Depression Rating Scale (HDRS), which was shown to display good reliability and validity in Chinese elders,44 was used to measure depressive symptoms. The 20-item Medical Outcomes Study−Social Support Survey (MOS-SSS), which was originally designed to assess social support in a community sample of patients with chronic illness,23 was used to measure social support. The Chinese version of MOS-SSS was shown to display good reliability and validity.45 Demographic characteristics including sex, age, education level, and marital status were collected. Data Analysis Descriptive analyses, the t test, and the x2 test were used to examine the basic characteristics of our sample. The t test was used to explore the difference of social support between uncontrolled HTN and controlled HTN. The Sobel Test46 for mediation analysis was conducted to examine the indirect association of the predictor, social support, via mediator, and depression severity, which was examined in relation to HTN control. The test was performed by using the model 4 of Andrew Hayes’47 PROCESS procedure for SPSS software Version 20 (IBM Corp., Armonk, NY). Using Ordinary Least Squares (OLS) regression-based path analysis, PROCESS covers the estimation of
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Zhu et al. various classes of models which allow indirect and/ or direct effects to be moderated.47 Path coefficients (a, b, c, and c’) representing the linear or logistic regression coefficients for each path in the mediation model were obtained. The a-path represents the association between the predictor (social support) and mediator variables (depression severity). The b-path denotes the relationship between the mediator (depression severity) and outcome variables (HTN control), while controlling for the predictor variable (social support). The c’-path (also called “direct effect”) and the c-path (also known as “total effect”) represent the associations between the predictor and outcome variables including and excluding the mediator variable, respectively.48 A statistically significant difference between c and c’ (c-c’= a £ b, a £ b was also known as “indirect effect”)49 is indication of a mediation effect. The typical 95% CIs were used to determine significance for the indirect effects, in which significance was obtained using bootstrapping with 5,000 resamples.50 Significance of indirect effect would be demonstrated with CIs not including zero.51,52 We used percent mediation as a measure of effect size, a measure of effect size interpreted as the percent of the total effect accounted for by the indirect effect.53,54 We then repeated the earlier mediation
analyses stratified by different components of social support to examine whether mediation effects were present in different components of social support. Age, sex, educational level, marital status, and Charlson Comorbidity Index were used as covariates in all analyses. These demographic factors have been commonly associated with HTN control in the literature.55,56 In the analysis, uncontrolled HTN was coded as 1, whereas controlled HTN was coded as 0. Depression and social support were treated as continuous variables identified by the HDRS-17 and MOS-SSS. All analyses were performed using SPSS software version 20 (IBM, Armonk, NY).
RESULTS Demographic Characteristics Table 1 displays the demographic characteristics of the sample in subgroups of HTN control. The independent-sample t test and the x2 test were used to examine differences in demographics between participants with uncontrolled or controlled HTN. Older patients with uncontrolled HTN had an older mean age and higher HDRS score compared with those
TABLE 1. Demographic Characteristics (N = 2,351) Demographics Characteristics
Controlled HTN
Uncontrolled HTN
Participant, N Female, N (%) Age, mean § SD Education, N (%) 0 years 1−5 years 6−8 years 9−11 years 12 years and more Marital status, N (%) Married Divorced Never married Widowed Formal separation HDRS-17, mean § SD Depression, N (%) Major depression Mild or moderate depression
668 457 (68.4) 73.61 § 8.30
1683 1110 (66.0) 74.79 § 8.18
351 (52.5) 266 (39.8) 42 (6.3) 7 (1.0) 2 (0.3)
937 (55.7) 655 (38.9) 77 (4.6) 10 (0.6) 4 (0.2)
415 (62.1) 3 (0.4) 4 (0.6) 246 (36.8) 0 21.21 § 3.50
977 (58.1) 12 (0.7) 21 (1.2) 671 (39.9) 2 (0.1) 22.21 § 4.28
137 (20.5) 531 (79.5)
419 (24.9) 1264 (75.1)
df
t/x2
1 2,349 4
1.30 3.16b 5.45
4
5.00
1,488
5.89c
1
5.10a
Notes: Major depression = HDRS more than 24; mild or moderate depression = HDRS 24 or less. SD: standard deviation. a Statistically significant at p < 0.05. b Statistically significant at p < 0.01. c Statistically significant at p < 0.001.
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Social Support, Depression, Hypertension its dimensions (emotional/informational support, tangible support, positive social interaction, and affection support) were significantly different in patients with controlled and uncontrolled HTN (Table 2).
with controlled HTN (Table 1). No difference was found in sex, education, and marital status (Table 1).
Association Between Social Support and HTN Control Mediation of Depression Severity
Table 2 illustrates difference in social support as well as its five components among subgroups of HTN control. The t test was used to explore the difference of social support between uncontrolled HTN and controlled HTN. The mean score of the full MOS-SSS and
Table 3 illustrates the mediation of depression severity. Increased depression severity was significantly associated with more social support and worse HTN control (Table 3). Higher MOS-SSS
TABLE 2. Independent-Sample Test on Social Support and HTN Control
MOS-SSS Emotional/informational support Tangible support Positive social interaction Affection support
Controlled HTN (N = 668) Mean § SD
Uncontrolled HTN (N = 1,683) Mean § SD
MD
df
ta
3.16 § 0.64 2.94 § 0.72 3.99 § 0.72 2.90 § 0.83 3.02 § 0.81
3.01 § 0.61 2.81 § 0.69 3.85 § 0.75 2.72 § 0.79 2.80 § 0.77
0.15 0.12 0.14 0.18 0.21
2,349 2,349 2,349 2,349 2,349
5.37 3.84 4.14 4.86 5.91
Notes: MD: Mean difference; SD: standard deviation. a Statistically significant at p < 0.001.
TABLE 3. Depression Severity Mediates the Association Between Social Support and HTN Control, with Age, Sex, Educational Level, Marital Status, and Charlson Comorbidity Index as Covariates (N = 2,351) Path a MOS-SSS
Emotional/informational support
Tangible support
Positive social interaction
Affection support
b t/Za df p b t/Z df p b t/Z df p b t/Z df p b t/Z df p
−0.84 −5.87 2326 <0.0001 −0.67 −5.04 2,326 <0.0001 −0.56 −4.81 2,326 <0.0001 −0.37 −3.61 2,326 0.0003 −0.65 −5.91 2,326 <0.0001
Path b 0.05 3.83 1 0.0001 0.05 4.00 1 0.0001 0.05 4.10 1 <0.0001 0.05 4.03 1 0.0001 0.05 3.71 1 0.0002
Path c
Path c’
−0.35 −4.44 1 <0.0001 −0.23 −3.38 1 0.0007 −0.16 −2.44 1 0.0148 −0.24 −4.04 1 0.0001 −0.33 −5.38 1 <0.0001
−0.31 −3.95 1 0.0001 −0.21 −2.95 1 0.0032 −0.14 −2.02 1 0.0439 −0.23 −3.72 1 0.0002 −0.30 −4.89 1 <0.0001
a £ b, 95% Bootstrapped CI for a £ b; p
Percent Mediation (PM)
−0.04 [−0.07, −0.02]; p = 0.0015
0.11
−0.03 [−0.06, −0.02]; p = 0.002
0.13
−0.03 [−0.05, −0.01]; p = 0.0021
0.18
−0.02 [−0.04, −0.01]; p = 0.0082
0.08
−0.03 [−0.05, −0.01]; p = 0.0018
0.09
Notes: The a-path represents the association between social support and depression severity. The b-path denotes the relationship between depression severity and HTN control, while also controlling for social support. The c-path and the c’-path represent the associations between social support and HTN control without and with depression severity included as a mediator, respectively. Age, sex, educational level, marital status, and Charlson Comorbidity Index used as covariates in all analyses. As a £ b = c − c’, the 95% CI for a £ b indicates that a significant medication has occurred when it does not include 0 and the c’ path is no longer significant. Percent mediation (PM) is a measure of effect size computed as (a £ b)/(c’+ a £ b). a T statistics for continuous variables and z statistics for binary variables.
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Zhu et al. scores correlated with worse HTN control, and this association became significant after controlling for depression severity (Table 3). There was a significant indirect effect on HTN control by social support through increased depression severity (a £ b = −0.04 [0.01]; bootstrap p = 0.0015; 95% CI: [−0.07, −0.02]). The mediator accounted for approximately 11% of the total effect (Table 3). Stratified analyses by different components of social support revealed significant mediation effects. For emotional/ informational support (a £ b = −0.03 [0.01]; bootstrap p = 0.002; 95% CI: [−0.06, ¡0.02]) with depression severity accounting for 13% of the total effect (Table 3). For tangible support (a £ b = −0.03 [0.01]; bootstrap p = 0.0021; 95% CI: [−0.05, ¡0.01]) with depression severity accounting for 18% of the total effect (Table 3). For positive social interaction (a £ b = −0.02 [0.01]; bootstrap p = 0.0082; 95% CI: [−0.04, ¡0.01]) with depression severity accounting for 8% of the total effect (Table 3). For affection support (a £ b = −0.03 [0.01]; bootstrap p = 0.0018; 95% CI: [−0.05, ¡0.01]) with depression severity accounting for 9% of the total effect (Table 3). Given the earlier-mentioned results, a partial mediation effect of depression severity in social support and HTN control existed. Consistent with the hypothesis, the results manifested that depression severity partially mediated the relationship between social support and HTN control. Different types of social support had differing impacts on HTN (Table 3).
DISCUSSION There is strong evidence linking social support to health outcomes, with a psychological factor generally considered as a potential pathway for both theoretical and applied reasons. However, the available recent literature provides no statistical evidence for this association. To the best of our knowledge, the present study is the first attempt to investigate the relationship between social support and HTN control in the Chinese aging population with an emphasis on role of depression severity within the association. Main findings show that older patients with poor social support are more likely to exhibit uncontrolled BP, an association that depression severity partially mediates. The finding that poor social support is significantly associated with higher risk of uncontrolled HTN is
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consistent with results of previous studies.15 Theoretically, social support is supposed to act as a buffer against stressors that are deleterious to health, protect individuals from some of the negative consequences of illnesses, and provide resources that facilitate adaptive coping in response to the illness.16−19 In these procedures, psychological responses are generally considered to play an important role. The unique contribution of this study lies in the finding that depression severity partially mediates the effect of social support on HTN control. That is, older people with poorer social support are at higher risk of developing depression and facing aggravated depression in the long run, which may in turn contribute to insufficient treatment of HTN.32 Specially, previous studies have revealed that patients with depression have lower adherence to the HTN treatment,32 which results in 50% of treatment failures.33,34 An important implication of this mediation effect is the medical priority of treating depression in older patients with HTN, or other chronic conditions. Indeed, the fact that chronic diseases are usually accompanied by mental disorders such as depression has been well recognized in recent research. There is also robust evidence that these comorbid mental disorders may adversely affect chronic disease care by, for instance, decreasing adherence to treatment;32 leading to higher functional impairment;57 increasing risk of complications and mortality;58 and increasing medical costs.59 In response to the increasing burden of mental disorders and frequent comorbidity with chronic illnesses, international calls focus on the integration of mental health interventions into existing primary care system. This would help reduce the burden of disease and disability associated with mental disorders, while simultaneously helping to achieve the desired outcomes for health conditions.60 Consistent with these initiatives, the present study supports and underlines the need of integrating depression and HTN care in Chinese primary care settings. Promising approaches toward this goal, which have been developed and well tested in Western nations, are primary care-based collaborative care models. Testing the effectiveness of these models is the objective of the COACH study. However, because mediation by depression is partial, even with depression treatment in patients with HTN, poor social support may still lead to poor HTN control. This finding emphasizes the importance of providing social support throughout depression and
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Social Support, Depression, Hypertension HTN management. In a collaborative care model that manages depression and HTN, resources of social support, such as the role of aging workers (social workers [SWs]) in the COACH study,41 should be integrated. Given that all four dimensions of support social were demonstrated to be highly related to HTN control, SWs were therefore trained to take corresponding measures regarding these aspects. For example, to provide emotional support and affection support, SWs were encouraged to listen to their clients seriously and patiently. To provide informational support, SWs could also improve the communications regarding disease and treatment between patients and PCPs and organize community-based education for patients and their families, so that they can better understand the diseases and treatment. Finally, other activities such as nutrition management and weekly visits to patients’ home provided tangible support and positive social interaction. Limitations for this study exist. First, the study sample lives in rural Zhejiang Province; therefore, the findings may not be generalizable to populations from urban areas or other developed countries. However, because depression and poor social support are common issues worldwide, findings may still lend insights to HTN management in a wide range of cultures and primary care settings. Second, the focus of this study was solely on older adults with depression and HTN, a group at very high risk for both poor social support and BP control. Nonetheless, the issue of social support likely applies to older adults with depression and any chronic condition. Future studies are recommended to examine these associations. Third, we used no diagnostic assessment of depression. Both categorical diagnosis and symptom severity of depression are important to consider in their relationships to HTN. Nonetheless, the PHQ-9 is a valid and effective measure of depressive symptom severity that is highly correlated with the diagnosis of major affective illness by the cutoff of 10 or more.
In addition, the HDRS, which was shown to display good reliability and validity in Chinese elders, was used to measure depressive symptoms. A more complete diagnostic assessment of depression should be included in further research. Fourth, the lack of measurement of related factors like antihypertensive treatments, under-prescribing, nonadherence, poor medical follow up, diet, exercise, weight, and financial resources and other related factors were limitations in understanding the relationships of interest. Antidepressant medications can influence BP, and the results of the PHQ-9 could be influenced by the use of those drugs. We acknowledge that antihypertensive treatments and other factors are closely related to HTN control. Further studies are necessary to fill these blank. Finally, the data of this study are cross-sectional, which prevented analysis of the longitudinal associations between social support, depression, and HTN. Therefore, further experimental or longitudinal studies are necessary to facilitate an evaluation of causality.
CONCLUSIONS Social support is significantly related to HTN control of older patients with depression in China, and depression severity partially mediates the association. Primary care-based collaborative care models are recommended to manage both depression and HTN in older Chinese adults. Finally, SWs should be integrated in those models to provide social support and better health outcomes. The authors thank research assistants (Yuxing Jiang, Jiayu Wang, Wenqi Weng, Xinlai Zhao, et al.) for their efforts in the data collection. This work was supported by the National Institutes of Health (grant number R01MH100298). Tingfei Zhu and Jiang Xue and co−first authors.
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