Voluntary work for the physical and mental health of older volunteers: A systematic review

BACKGROUND: The increasing imbalance between the number of older adults not working and the number of adults in the age range of labour force participation (age range 20–64) has long been a fundamental public policy challenge in the Organization for Economic Co‐operation and Development member countries. At a societal level, this growing imbalance raises serious concerns about the viability and funding of social security, pensions and health programmes. At an individual level, the concern is probably more that of aging well with the prospect of many years in retirement. Some research suggests that retiring for some carries the risk of a fast decline in health. Volunteering can play a significant role in people's lives as they transition from work to retirement, as it offers a “structured” means of making a meaningful contribution in society once the opportunity to do so through work has been cut off. Some older people consider voluntary work as a way to replicate aspects of paid work lost upon retirement, such as organisational structure and time discipline. In many countries, volunteering of the older adults is increasing and programmes designed specifically for this subpopulation are emerging. Volunteering may contribute to both individuals aging well and society aging well, as volunteering by the older adults at the same time relieves the societal burden if it helps maintain health and functionality for those who volunteer. It thus remains to be established to what extent volunteering impacts on the physical and mental health of those who volunteer. OBJECTIVES: The main objective of this review is to answer the following research question: what are the effects of volunteering on the physical and mental health of people aged 65 years or older? SEARCH STRATEGY: Relevant studies were identified through electronic searches of bibliographic databases, governmental and grey literature repositories, hand search in specific targeted journals, citation tracking, contact to international experts and internet search engines. The database searches were carried out to December 2018 and other resources were searched in September 2019 and October 2019. We searched to identify both published and unpublished literature. The searches were international in scope. Reference lists of included studies and relevant reviews were also searched. SELECTION CRITERIA: The intervention of interest was formal volunteering which can be described as voluntary, on‐going, planned, helping behaviour that intend to increase the well‐being of strangers, offers no monetary compensation and typically occurs within an organisational context. We included older people aged 65 or over who are engaged in formal voluntary work. The primary focus was on measures of physical and mental health. All study designs that used a well‐defined control group were eligible for inclusion. Studies that utilised qualitative approaches were not included. DATA COLLECTION AND ANALYSIS: The total number of potential relevant studies constituted 17,046 hits. A total of 90 studies, met the inclusion criteria and were critically appraised by the review authors. The 90 studies analysed 47 different populations. Only 26 studies (analysing 19 different populations) could be used in the data synthesis. Forty‐six studies could not be used in the data synthesis as they were judged to have too high risk of bias and, in accordance with the protocol, were excluded from the meta‐analysis on the basis that they would be more likely to mislead than inform. Eighteen studies did not provide enough information enabling us to calculate an effects size and standard error or did not provide results in a form enabling us to use it in the data synthesis. Finally, of the 26 studies that could be used in the data synthesis, two pairs of studies used the same two data sets and reported on the same outcome(s), thus in addition two studies were not used in the data synthesis. Meta‐analysis of both physical health outcomes and mental health outcomes were conducted on each metric separately. All analyses were inverse variance weighted using random effects statistical models that incorporate both the sampling variance and between study variance components into the study level weights. Random effects weighted mean effect sizes were calculated using 95% confidence intervals (CIs). Sensitivity analysis was carried out by restricting the meta‐analysis to a subset of all studies included in the original meta‐analysis and was used to evaluate whether the pooled effect sizes were robust across components of risk of bias. RESULTS: The 24 studies (analysing 19 different populations), used for meta analysis were from Australia, Ireland, Israel, Japan, Korea and United States, three were a randomised controlled trial and 21 were NRS. The baseline time period (the year the voluntary work that was analysed was measured) spanned by the included studies is 30 years, from 1984 to 2014 and on average the baseline year was 2001. On average the number of follow up years was 5, although with great variation from 0 to 25 years. The average number of volunteers analysed (not reported in four studies) was 2,369, ranging from 15 to 27,131 and the average number of controls was 13,581, ranging from 13 to 217.297. In total the average number of participants analysed was 14,566, ranging from 28 to 244.428. Ten studies analysed the effect of voluntary work on mortality, however, eight studies reported a hazard ratio and two studies reported an odds ratio. We analysed these two types of effect sizes separately. A hazard ratio <1 indicates that the treated, the volunteers is favoured. That is, the conditional mortality rate is lower for volunteers. All reported results indicated an effect favouring the volunteers, primary study effect sizes lied in the range 0.67–0.91. The random effects weighted mean hazard ratio was 0.76 (95% CI, 0.72–0.80) and statistically significant. The two studies that reported odds ratios of mortality supported this result. There was no heterogeneity between the studies in either of the meta analyses. Three studies analysed the effect of voluntary work on incident functional disability, using a hazard ratio as effect measure. All reported results indicated an effect favouring the volunteers, primary study effect sizes lied in the range 0.70–0.99. The random effects weighted mean hazard ratio was 0.83 (95% CI, 0.72–0.97) and statistically significant. There was a small amount of heterogeneity between the studies. Two studies analysed the effect of voluntary work on decline in instrumental activities of daily living, using an odds ratio as effect measure. Both reported results indicated an effect favouring the volunteers (0.63 and 0.83). The random effects weighted mean odds ratio was 0.73 (95% CI, 0.53–1.01) and not statistically significant. There is no heterogeneity between the two studies. Three studies analysed the effect of voluntary work on maintenance of functional competence, using an odds ratio as effect measure. All reported results indicated an effect favouring the volunteers, primary study effect sizes lied in the range 0.67–0.83. The random effects weighted mean odds ratio was 0.81 (95% CI, 0.70–0.94) and statistically significant. There is no heterogeneity between the studies. In addition a number of other physical outcomes were reported in a single study only. Three studies analysed the effect of voluntary work on depression, and reported results that enabled the calculation of standardised mean difference (SMD) and variance. The effect sizes are measured such that a positive effect size favours the volunteers. All reported results indicated an effect favouring the volunteers, primary study effect sizes lied in the range 0.05–0.66. The random effects weighted SMD was 0.12 (95% CI, 0.00–0.23) and statistically significant. There is a very small amount of heterogeneity between the studies. In addition, a number of other mental health outcomes were reported in a single study only. We did not find any adverse effects. There were no appreciable changes in the results across components of risk of bias as indicated by the sensitivity analysis. AUTHORS' CONCLUSIONS: The review aimed to examine effects on all types of physical and mental health outcomes. With the exception of mortality, there was insufficient evidence available. The available evidence, however, does suggest that there is an effect on the mortality of volunteers, although the effect is small. We found evidence that voluntary work reduces the mortality hazard of the volunteers aged 65 and above. The effect corresponds to a 43% chance of the volunteers dying first which should be compared to a fifty‐fifty chance (50%) of dying first if the intervention had no effect. The evidence seems robust in the sense that we did not find any heterogeneity between the studies. As the intervention, unlike most other interventions in the social welfare area, is not costly, it could be prescribed to more older adults. In fact as the intervention in contrary to carrying a cost is a productive activity contributing directly to community well‐being and has a positive effect on the volunteers it probably should be prescribed universally. However, due to the very nature of the intervention, it is voluntary and it cannot be prescribed. But more people could be encouraged to take up voluntary work if the opportunity was immediately available and visible.