Association Between Red Cell Index and Depressive Symptoms in NHANES (2005-2018): A Cross-sectional Study

Physical symptoms and emotional distress, such as melancholy, are common among cancer survivors. Misinterpreting these as normal reactions delays depression diagnosis and worsens prognosis. Patients may hide depressive symptoms during treatment, whereas clinicians and families often dismiss them as expected disease adaptation. Emerging evidence links depression to inflammatory responses and symptoms such as fatigue/cognitive decline to hypoxia, suggesting relevance of the Red Cell Index (RCI).

To identify depression risk factors in cancer survivors and evaluate RCI as a potential biomarker.

We included and analyzed 2890 patients from the National Health and Nutrition Examination Survey database in this study. The 9-item Patient Health Questionnaire was used to evaluate the depressive symptoms. We employed multivariable logistic regression and stratified analyses to evaluate the association between RCI and depressive symptoms.

Higher RCI inversely correlated with depression risk in unadjusted analysis, persisting after full adjustment. Subgroup findings were consistent. A significant nonlinear RCI-depression connection was found by dose-response analysis.

As the RCI increased, the likelihood of depression in patients diagnosed with cancer decreased. Nevertheless, cross-sectional studies can merely establish the link, necessitating further research to validate causality and assess the practicality of clinical use.

Possible connections between hematological markers and depression symptoms are revealed by this investigation. The RCI-depression correlation offers new perspectives for nursing practice. For cancer survivor care, integrating validated hematological indicators into assessments alongside monitoring physical/psychological symptoms is recommended. Future research should prioritize RCI-depression risk assessment and early interventions in oncology patients.