Learning Objective #1: Critique the methodological approaches used in the study of blood pressure (BP) and heart rate (HR) stress responses of caregivers

Learning Objective #2: Propose methodological alternatives to improve study design and measurement among African American women caregivers and noncaregivers

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BACKGROUND: Caring for a disabled elder can be stressful. Blood pressure (BP) and heart rate (HR) during sleep hold promise as stress indicators. During sleep, the influences of posture and activity are minimized, facilitating evaluation of the influence of caregiver status and perceived stress on BP and HR.

DESIGN: Case-control design of caregivers and noncaregivers.

POPULATION, SAMPLE, SETTING, YEARS: Random sample of African American (AA) women (age 18+) who were caregivers for disabled older (65+) adults (n=193) and AA women living in the community who were potential caregivers (n=179) in their homes.

Variables studied: sleep BP, HR, caregiver status, perceived stress, covariates (age, body mass index, alcohol, hypertension treatment, smoking, exercise).

Methods: After informed consent, nurses interviewed, and attached the ambulatory BP monitor to participants. BP and HR were recorded every 60 minutes 10PM to 6AM (sleep BP). Participants recorded bed and awakening times and nighttime activity. Separate hierarchical linear regressions entering caregiver status, perception of stress, and their interaction in the first block; potential covariates in the second block for each outcome: mean systolic BP, diastolic BP, and HR.

FINDINGS: Caregiver status, perceived stress, and their interaction did not explain SBP or DBP during sleep. Covariates explained 23% of SBP (p<.05) and 9% of DBP (p<.05) variances. For HR, perceived stress contributed 1.4% (p<.05); covariates added 8.6% (p<.05).

CONCLUSIONS/METHODOLOGICAL IMPLICATIONS: Cardiovascular stress responses of AA caregivers and noncaregivers do not differ during sleep, contrary to findings of higher awake BPs among Caucasian caregivers. Perceived stress explained HR, caregiver status did not. Other factors may explain the different relationships of these variables to cardiovascular status in AA and Caucasian women. Future studies of caregiver stress would benefit from attention to SAMPLE (homogeneous caregiver group), ENVIRONMENT (posture, location, activity), MEASUREMENT (operationalzing caregiver status and stress responses) and DATA ANALYSIS (incorporating moderators).