A Longitudinal Analysis of Inflammation and Depression in Patients With Metastatic Lung Cancer: Associations With Survival

Background: Depression and inflammation are concomitantly elevated in patients with lung cancer and may have collective survival implications. However, the longitudinal relationship between depression and inflammation in patients with metastatic lung cancer is not fully appreciated. We hypothesized that longitudinal changes in inflammation and depression would be concordant; that longitudinally elevated inflammation would lead to greater depression over time; and that depression with inflammation would be more persistent than depression without inflammation. Methods: Patients with metastatic lung cancer (n = 68) were assessed for clinically significant depression (Hospital Anxiety and Depression Scale >= 8) and inflammation (C-Reactive Protein >= 1 mg/L) along with demographic variables. Survival estimations were made using Cox Proportional Hazard Model and Kaplan-Meier plot analyses. Results: At baseline (T1), 15% had depression and 35% had increased inflammation followed by 18% with depression and 38% with increased inflammation 4.7 months later (T2). The odds ratio of depression in the presence of clinically significant inflammation was 4.8 at T1 and 5.3 at T2. Between time points, inflammation difference correlated with depression difference (r = -.26,p= .03). Significant depression atboth time pointswas associated with a 4 fold risk of inferior survival while significant inflammation atany time pointwas associated with >3 fold risk of inferior survival. Conclusions: Depression and inflammation track together over time and have variable implications on survival. Persistent depression is particularly detrimental but incidental inflammation is more sensitive to predicting poor survival. These findings have implications for treating depression early in the lung cancer trajectory.