The typical caregiver for an elderly patient with functional limitations is the patient's spouse or adult child. Previous studies have shown that caregivers suffer impaired health as a result of their caregiver status. For example, delayed wound healing, increased rates of depression and increased rates of serious illness have occurred in caregivers. Schulz and Beach conducted this prospective cohort study to determine the relationship between caregiving stress and mortality.

Part of the Cardiovascular Health Study was the Caregiver Health Effects Study, from which data for this study were taken. Patients more than 65 years of age were included in this study if they lived in the community and had their spouse as their caregiver. Patients were excluded if they were confined to a wheelchair or were receiving treatment for cancer. The patient was defined as having difficulty with at least one activity or instrumental activity of daily living (ADL or IADL) because of physical or cognitive problems. Two groups were identified: the caregivers group (as defined above) and patients who had a spouse living with them but who did not require caregiving (the noncaregiver group). Caregivers were categorized as having a prevalent disease (such as angina or congestive heart failure), a subclinical disease (such as a major electrocardiographic abnormality) or no prevalent or subclinical disease. The spouse was asked if the patient had difficulty with any of six ADLs or six IADLs. If the answer was “yes,” the spouse was then asked whether he or she helped the patient with the activity. If the answer to that question was “yes,” the spouse was classified as a caregiver, and the level of emotional stress was categorized as “no strain,” “some strain,” or “a lot of strain.”

Participants in the study were placed in four groups based on these categorizations: the control group (spouse not disabled); spouse disabled but requiring no help; spouse disabled and no caregiver strain; and spouse disabled and caregiver strain. The dyads were followed for 3.4 to 5.5 years. The study recruited 392 caregivers and 427 noncaregivers. The mean age of the caregivers was 80 (range: 66 to 96). Of participants with disabled spouses, most (81 percent) were considered caregivers and about one half of those (56 percent) reported strain. During the four-year follow-up period, 9.4 percent of the spouses in the control group died, compared with 17.3 percent in the disabled-but-requiring-no-help group, 13.8 percent in the disabled-and-no-caregiver-strain group and 17.3 percent in the disabled-and-caregiver-strain group. However, after adjusting the results for age, sex, race, education and physical health (the prevalent disease and subclinical disease), the caregivers who reported strain had a 63 percent higher mortality risk than participants whose spouse was not disabled. The other participants with disabled spouses did not have a similarly increased mortality risk after these adjustments. The authors conclude that caregiver strain, even when spouses are minimally disabled, is associated with increased mortality rates.

The authors call for simultaneous attention to both partners when one is a caregiver for the other. In an accompanying editorial, Kiecolt-Glaser and Glaser encourage physicians to assess psychosocial and biomedical factors in the couple, not just in the patient.