Abstract and Introduction
Abstract
Previous studies have provided conflicting evidence on whether being a family caregiver is associated with increased or decreased risk for all-cause mortality. This study examined whether 3,503 family caregivers enrolled in the national Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study showed differences in all-cause mortality from 2003 to 2012 compared with a propensity-matched sample of noncaregivers. Caregivers were individually matched with 3,503 noncaregivers by using a propensity score matching procedure based on 15 demographic, health history, and health behavior covariates. During an average 6-year follow-up period, 264 (7.5%) of the caregivers died, which was significantly fewer than the 315 (9.0%) matched noncaregivers who died during the same period. A proportional hazards model indicated that caregivers had an 18% reduced rate of death compared with noncaregivers (hazard ratio = 0.823, 95% confidence interval: 0.699, 0.969). Subgroup analyses by race, sex, caregiving relationship, and caregiving strain failed to identify any subgroups with increased rates of death compared with matched noncaregivers. Public policy and discourse should recognize that providing care to a family member with a chronic illness or disability is not associated with increased risk of death in most cases, but may instead be associated with modest survival benefits for the caregivers.
Introduction
The increasing number of older adults, rising prevalence of many chronic diseases, and greater emphasis on noninstitutional care are requiring a greater number of individuals to serve as informal caregivers of family members with chronic illnesses or disabilities. These family caregivers often endure substantial life changes and chronic stressors that several studies suggest are linked to deleterious health effects, including increased risk of death. A widely cited landmark study of spouse caregivers, the Caregiver Health Effects Study (CHES), found that those who were providing care to a disabled spouse and who reported some strain associated with that care had a 63% elevated risk of death compared with noncaregiving spouses. Increased rates of death have also been reported for the spouses of partners who have recently been hospitalized. Along with findings from many studies that suggest caregivers have poorer mental and physical health status than noncaregivers, caregiving has been widely portrayed as a serious public health problem in the professional literature and as a threat to survival in the popular media (e.g., "the most devoted family caretakers are at risk of dying first themselves" (10, p. 70)).
Despite these common conclusions that caregiving presents a health risk that could extend to increased risk of death, several other recent studies have provided opposing evidence and suggested that caregiving may actually be associated with preserved health over time and reduced risk of death. Married participants from the Health and Retirement Study providing 14 or more hours of care per week to their spouses who had problems with activities of daily living or instrumental activities of daily living were found to have reduced rates of death compared with spouses who provided no such care. An analysis of Northern Ireland census data found that individuals who reported family caregiving responsibilities had lower 4-year death rates than noncaregivers. Fredman et al. reported that older American women who engaged in informal caregiving activities had lower 8-year death rates than a corresponding sample of noncaregiving women, and that higher levels of physical performance (e.g., walking speed, strength measures) were maintained over a 2-year period among the caregivers who provided a high level of assistance with activities of daily living or instrumental activities of daily living.
Several factors might partially explain the findings of preserved health and lower rates of death among some caregiving samples. These factors form the core of the "healthy caregiver hypothesis" and include both possible selection processes and potential psychological and social benefits of caregiving. Selection factors concern who takes on informal caregiving responsibilities when a family member becomes seriously ill or disabled. One population-based study found that healthier individuals were more likely to take on and endure in family caregiving roles over time. Health and resource factors might be especially important in the selection of nonspouse caregivers. Other investigators have noted the potential positive aspects of caregiving, including possible health and longevity benefits for individuals who become more active themselves when volunteering or providing help and support to others.
One topic that is rarely addressed is whether the mortality effects of caregiving are similar across different subgroups of caregivers. Caregivers are an incredibly diverse group consisting of many relationship subtypes (e.g., spouses, adult children, and others) who handle different types of care recipient problems. Caregivers may or may not live with their care recipients and may perceive different levels of caregiving strain. Existing studies of the caregiving-mortality association in the United States have not only led to conflicting findings, but have also been limited to spouse caregivers or female caregivers. Population-based studies of caregivers and matched noncaregiving controls that include larger numbers of minority participants and more diverse and representative relationship subtypes are needed to further inform this important area of investigation.
A promising analytical approach for examining potential causal variables that cannot be subjected to random assignment is through the use of propensity scores that can be obtained from large observational data sets. In this approach, individuals who are exposed to a treatment (or a risk factor) are compared with a selected comparison group of untreated individuals, such that both groups are balanced on a wide range of potential confounding factors. Large, population-based, observational studies that assess caregiving status as 1 of a range of contextual variables provide a unique opportunity to implement this approach and to examine the health effects of caregiving after controlling for many confounding variables. However, to our knowledge, no previous study of the caregiving-mortality association has compared caregivers with a matched sample of noncaregivers by using an empirical, propensity score matching procedure.
In this study, family caregivers were identified from a large national epidemiologic study and confirmed to differ from noncaregivers on a range of demographic, medical history, and health behavior variables. A logistic regression, propensity-matching algorithm was used to individually match and balance caregiving and noncaregiving subgroups, and survival analysis methods were then used to examine subsequent all-cause mortality rates. We also conducted supplemental analyses to examine whether the mortality effects of caregiving were comparable across races and sexes, between caregivers of parents versus spouses, and among those with different levels of self-reported caregiving strain to see if different patterns would emerge among subgroups that might partly explain the previous contradictory findings.