Fatigue, physical function, and the context of social vulnerability for older adults with cancer

Older adults with cancer-related fatigue often experience impairments in their physical function. Social determinants of health (SDOH) at the individual and community level may mean some patients have fewer resources to deal with fatigue and are at greater risk for decline in physical function.

We analyzed patients age ≥ 70 with advanced cancer and ≥ 1 aging-related impairment who were starting new treatment regimens with a high risk of toxicity in a nationwide cluster-randomized clinical trial (NCT02054741, UG1CA189961). Patient-Reported Outcome Common Terminology Criteria for Adverse Events (PROC-CTCAE) fatigue severity (0-4 points) was collected at baseline, Short Physical Performance Battery (SPPB, a measure of physical function, 0-12 points) at baseline, 4-6 weeks, 3 months, and 6 months. SDOH in the county where patients lived were measured by the Social Vulnerability Index (SVI, a measure reflecting community vulnerability, 0 to 1, higher = worse). We estimated adjusted relative risk (RR) of ≥1 point SPPB decline at 4-6 weeks associated with baseline fatigue. In exploratory analyses we estimated: (1) this association at 3 and 6 months, (2) moderation of this association by SVI.

Out of 718 patients, we analyzed 600 with SPPB assessed at ≥1 follow up timepoint. Half reported fatigue that was moderate or greater, and 38.8 % declined in SPPB by 4-6 weeks. Mean SVI was 0.42 (SD 0.23). Greater fatigue was associated with increased risk of SPPB decline at 4-6 weeks (RR 1.21; 95 % CI 1.09, 1.34, p < 0.001), but not 3 or 6 months. The association at 4-6 weeks was not significantly different for patients living in areas with the least vulnerable quartile of SVI (RR 1.27, 95 % CI 1.05, 1.53) vs. the most vulnerable (RR 1.22, 95 % CI 0.91, 1.65; p = 0.85).

Fatigue is associated with decline in physical function among older adults with advanced cancer and does not vary by social vulnerability. These results emphasize the importance of assessing and managing fatigue in this population.