Sleep Quality and Its Determinants Among Patients with Metastatic Cancer Treated with Immune Checkpoint Inhibitors: A Two-Center Cross-Sectional Study

<i>Background and Objectives</i>: Sleep disturbance (SD) is common among cancer patients and may be influenced by immune-related mechanisms during immune checkpoint inhibitor (ICI) therapy. This study evaluated the prevalence and predictors of SD in patients receiving ICIs. <i>Materials and Methods</i>: This retrospective, two-center study included 187 patients with advanced or metastatic cancers. Sleep quality was assessed at three months using the Pittsburgh Sleep Quality Index (PSQI). Patients were categorized as having no SD (PSQI ≤ 5) or SD (PSQI > 5). Logistic regression analyses identified predictors of SD. <i>Results</i>: Clinically relevant SD was observed in 97 patients (51.9%), with a mean PSQI score of 7.54 ± 5.39. The most affected PSQI components were SD (1.33 ± 1.05) and daytime dysfunction (1.21 ± 1.04). In univariate analyses, Eastern Cooperative Oncology Group (ECOG) performance status ≥ 1 (Odds ratio [OR]: 3.29, 95% confidence interval [CI] 1.77-6.08, <i>p</i> < 0.001), second-line or beyond therapy (OR: 3.76, 95% CI 1.92-7.34, <i>p</i> < 0.001), ≥ 2 metastatic sites (OR: 2.69, 95% CI 1.47-4.92, <i>p</i> = 0.001), and ≥6 ICI cycles (OR: 1.85, 95% CI 1.04-3.32, <i>p</i> = 0.036) were associated with SD. In multivariate analysis, ECOG ≥ 1 (OR: 2.33, 95% CI 1.17-4.62, <i>p</i> = 0.015), second-line or beyond therapy (OR: 2.43, 95% CI 1.14-5.16, <i>p</i> = 0.021), and ≥ 2 metastatic sites (OR: 2.10, 95% CI 1.06-4.16, <i>p</i> = 0.032) remained independent predictors. <i>Conclusions</i>: Over half of patients treated with ICIs experienced SD. Poor performance status, advanced disease burden, and later-line therapy independently predicted impaired sleep, supporting the routine assessment of sleep during ICIs.