Depression Moderates Physical Functioning Over Time in Survivors of Cancer

Background: Cancer survivors are at risk for declines in physical functioning (PF). The strongest predictor of PF is prior PF. Clinically significant depression predicts declines in PF; however, the extent to which depression symptoms moderate the association between self-reported and performance-based measures of PF over time is unknown. Objective/Purpose: To examine whether level of depression symptoms in cancer survivors moderates the association of repeated self- and performance-based measures of PF at 6 and 18 months after cancer diagnosis. Methods: Prospective, observational study with assessment at 6 (T1), 12 (T2), and 18 months after cancer diagnosis (T3). Setting and Patients: Community-dwelling US veterans with newly diagnosed head and neck, esophageal, gastric, or colorectal cancers. Measurements: Measures included demographics, cancer variables (type, stage, severity, and treatment), depression symptoms (Patient Health Questionnaire-9 [PHQ-9]), Short Physical Performance Battery (SPPB), and self-reported PF (Patient-Reported Outcomes Measurement Information System-29 [PROMIS-29]). Results: Using hierarchical regression models, after adjustment for covariates, depression symptoms at T2 moderated the relationship between performance-based PF, SPPB (β = −0.24, P = .001) but not self-reported PF, PROMIS (β = −0.14, P = .05). In moderation analyses, SPPB T1 was only related to SPPB T3 when the PHQ-9 score was less than 9. Limitations: Majority White, male participants, did not measure chronicity of depression. Conclusions: Depression symptoms moderate the relationship of performance-based PF from baseline to 18 months.