**Background:** Adherence to physician recommendations is critical for older adults with chronic conditions, yet predictors remain poorly understood. Prior research has focused on medication adherence and physician-patient relationships, but the influence of patients' health-related locus of control beliefs—whether they attribute health outcomes to internal actions, external forces like health professionals, or luck—has been underexplored. This study aimed to examine how multidimensional health-related locus of control beliefs, cognitive functioning, and multimorbidity affect adherence to physician recommendations among community-dwelling older adults.
**Methods:** Data came from wave 3 (1992) of the Successful Aging Study conducted among independent retirement community residents in Clearwater, Florida. The analytic sample included 684 older adults (mean age 80.70 years, SD=4.51; 65.20% female; 46.05% married; mean education 13.63 years). Adherence was measured by asking "How often do you follow advice provided by your physician or medical care provider?" with responses recoded into three categories: always (68.27%), frequently (23.54%), and less than frequently (8.19%). Health-related locus of control was assessed using nine items from the Multidimensional Health Locus of Control scale (e.g., "Health professionals control my health," "Main thing that affects my health is what I myself do"), each on a 1–5 Likert scale. Cognitive impairment was measured using the 10-item Short Portable Mental Status Questionnaire (SPMSQ), with 21.35% classified as having impairment (≥3 errors). Multimorbidity was the sum of 17 chronic conditions (mean=3.54, SD=2.01). Disability was assessed using Lawton's ADL/IADL scales (mean=1.39, SD=3.31). Self-rated health was categorized as excellent (27.78%), good (40.20%), or poor/fair (32.02%). Ordered logistic regression was used, with the proportional odds assumption confirmed (Brant test p=0.591).
**Key Results:** In the fully adjusted model (Model 2), several health-related locus of control beliefs significantly predicted adherence. Older adults who more strongly believed that "Health professionals control my health" had 34% higher odds of greater adherence (OR=1.34, 95% CI: 1.11–1.58, p<0.001). Those who believed "I recover because of other people taking good care of me" had 26% higher odds (OR=1.26, 95% CI: 1.13–1.51, p<0.05). Conversely, older adults who believed "Main thing that affects my health is what I myself do" had 27% lower odds of adherence (OR=0.73, 95% CI: 0.55–0.97, p<0.01). Those who believed "My good health is largely a matter of good fortune" had 19% lower odds (OR=0.81, 95% CI: 0.68–0.95, p<0.05). The item "Regarding my health, I can only do what my doctor tells me to do" was not significant (OR=1.14, 95% CI: 0.92–1.41, p>0.05). Cognitive impairment was associated with 38% lower odds of adherence (OR=0.62, 95% CI: 0.41–0.90, p<0.05). Self-rated health (OR=1.07, 95% CI: 0.85–1.36), disability (OR=1.05, 95% CI: 0.98–1.12), and multimorbidity (OR=0.98, 95% CI: 0.89–1.07) were not significant. Age was positively associated with adherence (OR=1.07 per year, 95% CI: 1.03–1.11, p<0.001). Gender, marital status, education, and total doctor visits were not significant.
**Clinical Implications:** This study demonstrates that health-related locus of control beliefs are important predictors of adherence to physician recommendations among older adults, independent of physical health status. Contrary to the hypothesis, internal locus of control (belief in personal control over health) was associated with lower adherence, possibly because these individuals feel less need for medical advice. External locus of control beliefs (trust in health professionals or others) were associated with higher adherence, suggesting that fostering trust and collaborative relationships may improve adherence. Cognitive impairment significantly reduced adherence, highlighting the need for simplified regimens and caregiver support. The lack of association with multimorbidity and functional limitations suggests that beliefs and cognition may be more influential than disease burden alone. Clinicians should assess patients' health beliefs and cognitive status to tailor communication and support strategies, potentially improving adherence and health outcomes in older adults.