Cancer-related drowsiness (CRD) is a distressing symptom in advanced cancer patients (ACP). The aim of this study was to determine the frequency and factors associated with severity of CRD. We also evaluated the screening performance of Edmonton Symptom Assessment Scale-drowsiness (ESAS-D) item against the Epworth Sedation Scale (ESS).

We prospectively assessed 180 consecutive ACP at a tertiary cancer hospital. Patients were surveyed using ESAS, ESS, Pittsburgh Sleep Quality Index, Insomnia Severity Index, and Hospital Anxiety Depression Scale.

Ninety of 150 evaluable patients had clinically significant CRD (ESS); median (interquartile ratio): ESS. 11 (7–14); ESAS-D. 5 (2–6); Pittsburgh Sleep Quality Index. 8 (5–11); Insomnia Severity Index. 13 (5–19); Stop Bang Scoring 3 (2–4), and Hospital Anxiety Depression Scale-D 6 (3–10). ESAS-D was associated with ESAS (r, p) sleep (0.38, <0.0001); pain (0.3, <0.0001); fatigue (0.51, <0.0001); depression (0.39, <0.0001); anxiety (0.44, <0.0001); shortness of breath (0.32, <0.0001); anorexia (0.36, <0.0001), feeling of well-being [(0.41, <0.0001), ESS (0.24, 0.001), and opioid daily dose (0.19, 0.01). Multivariate-analysis showed ESAS-D was associated with fatigue (odds ratio [OR] = 9.08, p < 0.0001), anxiety (3.0, p = 0.009); feeling of well-being (OR = 2.27, p = 0.04), and insomnia (OR = 2.35; p = 0.036). Insomnia (OR = 2.35; p = 0.036) cutoff score ≥3 (of 10) resulted in a sensitivity of 81% and 32% and specificity of 70% and 44% in the training and validation samples, respectively.

Clinically significant CRD is frequent and seen in 50% of ACP. CRD was associated with severity of insomnia, fatigue, anxiety, and worse feeling of well-being. An ESAS-D score of ≥3 is likely to identify most of the ACP with significant CRD.