Geriatr Gerontol Int 2016; 16: 693–700
ORIGINAL ARTICLE: EPIDEMIOLOGY, CLINICAL PRACTICE AND HEALTH
Living arrangements, social networks and onset or progression of pain among older adults in Singapore Ying-Ying Leung,1,2 Suat Lay Teo,3 Ming Boon Chua,2 Prassanna Raman,1 Chang Liu1 and Angelique Chan1 1
Clinical Sciences, Duke-NUS Graduate Medical School, 2Department of Rheumatology & Immunology, Singapore General Hospital, and Yong Loo Lin School of Medicine, National University of Singapore, Singapore
Aims: We aimed to evaluate the relationship between living arrangements, and strength of social network with onset and progression of chronic pain over 2 years in elderly Singaporeans. Methods: We used data from the Social Isolation Health and Lifestyles Survey, a nationally representative survey of community-dwelling older Singaporeans aged >60 years (n = 4990) in 2009 and follow up in 2011. We used binomial logistic regression models to examine factors associated with self-reported onset and progression of chronic pain over time. Results: A total of 3103 participants (53.8% women) completed both surveys (weighted response rate 63.7%). The mean age (SD) was 69.4 (0.5) years. The prevalence of mild and moderate-extreme chronic pain at baseline were 27.7% and 12.8%. A total of 20.1% and 3.9% of the participants reported having chronic pain onset and progression over 2 years, respectively. In the binomial regression models, lower education level, living alone and poorer self-rated health were predictors for onset of chronic pain in women. Weak social networks and disability were associated with progression of chronic pain in women. Conclusions: Chronic pain is common in Singaporean older adults. Living alone and weak social network were sociopsychological factors associated with the onset or progression of chronic pain. Geriatr Gerontol Int 2016; 16: 693–700. Keywords: chronic pain, cohort study, pain progression, Singapore elderly, social isolation, social network.
Introduction Chronic pain causes substantial economic costs to society, and is a major public health concern.1,2 The negative consequences of chronic pain are particularly significant amongst older adults, as many lose independence and require help with daily living because of the pain. Studies from Caucasian countries have shown a high prevalence of chronic pain that is associated with increased age, women and disability.1–3 Identifying factors that contribute to the development and progression of chronic pain among older adults is important for prevention of chronic pain and the associated disabilities.
Accepted for publication 22 April 2015. Correspondence: Dr Ying-Ying Leung MB.ChB, Senior Consultant, Department of Rheumatology and Immunology, Singapore General Hospital, Level 4, The Academia, 20 College Road, S169856 Singapore. Email: [email protected]
© 2015 Japan Geriatrics Society
Social relationships and social support are important factors in the maintenance of health and well-being. There is increasing evidence that socially isolated individuals are at increased risk of cardiovascular diseases,4,5 infection,6 depression7 and even mortality.5,8 In contrast, strong social network and family support have a protective effect on mental well-being.7 The elderly population is especially vulnerable to social isolation because of the reduction in economic resources, mobility impairment and death of spouse and peers. Previous cross-sectional studies have shown a positive association between social support and intensity of pain for patients with chronic illness.9,10 Psychological factors were shown to predict the onset of chronic widespread pain in a prospective community study.11 We hypothesized that older adults with a lower level of social support are more likely to experience the onset of chronic pain and progression of chronic pain. Currently, there is no study on the relationship between social network and the onset and/or progression of pain amongst the elderly population in Asia. In the present doi: 10.1111/ggi.12539
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study, we aim to evaluate social networks in relation to transition of pain in a national representative cohort of older adults over a 2-year period.
Methods Study population We used prospective data from the Social Isolation Health and Lifestyles Survey (SIHLS), a nationally representative survey of community-dwelling Singaporeans aged 60 years and older (n = 4990) carried out by the Ministry of Community Development, Youth and Sports in 2009, and the follow up survey in 2011. The sample was stratified by sex, ethnic group and 5-year age groups based on the 2007 population distribution. Individuals aged ≥75 years and ethnicities (Malays and Indians) were oversampled by a factor of 2 to ensure sufficient sample size for subgroup analysis. Further details of the sampling methodology are published elsewhere.7 A total of 4990 participants were interviewed face-to face by trained personnel at their residence (weighted response rate 69.4%) using a standardized questionnaire in 2009. Proxy interviews were carried out for 453 participants (9.1%) who were unable to respond because of health reasons, and these were excluded from the present analysis. Data from the SIHLS were merged with the National Death Registry (16 January 2009 to 30 April 2012) of the Ministry of Health of Singapore. At the follow-up survey in 2011, a total of 3103 participants were successfully re-interviewed (weighted response rate 63.7%). A total of 3.8% participants of the original cohort had died, 23.7% refused a second survey and 8.5% were not contactable. The final cohort included 3103 community-dwelling older Singaporeans who answered the chronic pain question at both time-points. The studies were approved by the institutional review board of the National University of Singapore. All participants signed an informed consent before both surveys.
Outcome variable: Chronic pain Participants were asked to respond to the question: “Overall, in the past 30 days, how much of bodily aches or pains did you have (none, mild, moderate, severe and extreme)?”. In the present study, we defined chronic pain as having lasting mild pain and above in the past 30 days. The number of painful sites in the body was associated with the onset12 and progression13 of disability; and it might affect pain transition. Participants were also asked about the presence or absence of pain in different areas of the body (head, neck, shoulders, joints of the hands and arms, chest, abdomen, back, lower back, waist, joints of the legs). 694 |
In the present study, we restricted the “chronic pain onset” sample to those who reported no pain at baseline. Within this sample, participants who reported no pain at the second time-point were categorized as not having pain onset (0), whereas those who reported mild or moderate to severe pain at the second time-point were categorized as having pain onset (1). Multiple dimensions of pain, including pain intensity, has been shown to be associated with disability outcomes, and therefore, we wanted to focus on capturing the transitions to moderate-severe pain.14 We defined the “onset/progression to moderate-severe pain” as participants who reported no pain or mild pain at baseline, and progressed to have moderate-severe pain at follow up. Those who continued to report no or mild pain at the second time-point were categorized as having no progression (0), and those who reported moderate-extreme pain at the second time-point were categorized as having “onset/progression to moderate-severe pain” (1).
Main independent variables: Living arrangements and social networks Participants were classified into three mutually exclusive groups in terms of their living arrangements: (i) living alone; (ii) living with only one other person; and (iii) living with two or more other people. “Other people” included a spouse or child, or any person apart from a spouse or child, which could be a parent, sibling or other cohabitant. We used the Lubben’s revised social network scale to assess the social networks of the respondents outside the household.15 The scale consisted of 12 items (six for social networks with friends and six for social networks with relatives outside the household) assessing the size of network, frequency of contact, closeness, and perceived support from friends and relatives outside of the household. Each item was scored on a six-point scale from 0 to 5. The scale has been utilized as the standardized scale for the assessment the SIHLS. In a former study, it showed good internal consistency reliability (Cronbach’s alpha = 0.92) and a two-factor structure.7 The total variance explained by the two factors was 43.9% (network strength with friends) and 41.8% (network strength with relatives outside the household), with a minimum factor loading of 0.70. Strong/weak social networks were defined as the upper/lower quartiles of the Lubben’s scale distribution at baseline. The degree of involvement in social activities was assessed through its frequency (everyday, week, month, less than once a month, not at all) and the number of activities attended (attending a resident/community development committee, neighborhood event or a church/mosque/other places of worship.) Subjective feeling of loneliness was assessed by the three-item loneliness questionnaire, which was adapted © 2015 Japan Geriatrics Society
Living alone and progression of pain
from the Revised University of California, Los Angeles loneliness Scale.16 The three-item loneliness questionnaire measures three components of loneliness: feeling left out, feeling isolated or lack of companionship. A higher score indicates a higher degree of perceived loneliness.
Other covariates The analysis was adjusted for the following baseline demographic factors including age, sex, education (none, any formal education received), marital status (married, widowed, separated, divorced, never married) and ethnic group (Chinese; Malay; Indian; Others). Self-reported household income was not included in the analysis, as 20% of this data was missing; those not reporting household income were more likely to be older, women and Malay or Indian. Instead, we used housing type (1–2 room public, 3 or more room public, condominium/landed property) as a proxy for socioeconomic status, as this method has been shown to be reliable in the local setting.7 Depression is a well-known risk factor for pain, and it was assessed by a modified version of the 11-item Center for Epidemiologic studies for Depression (CES-D) scale.17 Each item on the scale was scored 0 to 2 (none/rarely; sometimes; often) depending on how often the respondent felt that way during the past week. The total score ranged from 0 to 22. Those with a score of >7 were classified as having clinically relevant depressive symptoms. The 11-item Center for Epidemiologic studies for Depression scale used in SIHLS showed good internal consistency reliability (Cronbach’s alpha = 0.77) and a four-factor structure (depressed affect, positive affect, somatic complaints and interpersonal problems), which was similar to that previously reported in the validation study. Physical function and mobility impairment can cause social isolation. We assessed activities of daily living (ADL) limitation through the following seven activities (bathing, dressing, eating, standing up/sitting down on a bed/chair, walking around the house, going outside the house and using the toilet). Instrumental activities of daily living (IADL) limitation was assessed through the following seven activities (preparing meals, leaving home to purchase necessary items/medication, taking public transport, taking care of financial matters, using the phone, dusting/cleaning or doing other light housework, taking medication). The options given to participants to assess both ADL and IADL were “(i) Difficult, (ii) Not difficult and (iii) Not sure”. Participants were considered to have limitation in a particular ADL or IADL activity when they answered “(i) Difficult”. The number of limitations in ADL or IADL was used as control variables in the analysis. Body mass index (BMI) might have an impact on the transition of pain symp© 2015 Japan Geriatrics Society
toms. Body weight and height were measured by trained interviewers, and the BMI was calculated as weight in kilograms/square of height in meters (kg/m2). Other variables analyzed include: presence or absence of a domestic helper in the household, self-rated general health (excellent, fair, poor), number of self-reported chronic illness from the following list (angina/ myocardial infarction/any other heart condition, cancer, cerebrovascular diseases, high blood pressure, diabetes, respiratory illness, osteoporosis, cataract, glaucoma). As pain from recent fracture usually resolves with time, we kept the presence or absence of recent fracture within the past 1 year separated from other comorbidities.
Statistical analysis The prevalence of moderate or severe chronic pain was described by age, sex and ethnicity. Binomial logistic regression analysis was used to assess the relationship of living arrangement, perceived loneliness and social network variables with transition of chronic pain over 2 years, controlling for other potential risk factors discussed before. Two models were analyzed separately: (i) onset of chronic pain – comparing participants who reported no pain at both baseline and follow up with those who transitioned from no pain at baseline to mildmoderate extreme pain at follow-up, and (ii) progression of chronic pain – comparing participants who reported no or mild pain at both baseline and follow up with those who transitioned from no or mild pain at baseline to moderate-extreme pain at follow up. We also carried out stratified analysis by sex. We carried out all statistical analyses using STATA Version 12 (StataCorp, College Station, TX, USA). Two-tailed P-values of