The Pittsburgh Sleep Quality Index (PSQI) Applied to Cancer Patients: Psychometric Properties and Factors Affecting Sleep Quality

Objective: Cancer patients frequently report sleep problems. The Pittsburgh Sleep Quality Index (PSQI) is a 19-item instrument for assessing sleep problems. The main objective of this study was to analyze the usefulness of the PSQI in oncological research. Methods: A sample of 1,733 cancer patients with mixed diagnoses were included. In addition to the PSQI, the following questionnaires were adopted: the Insomnia Severity Index (ISI), the Jenkins Sleep Scale (JSS) and the sleep scale of the EORTC QLQ-SURV100. Results: The internal consistency of the PSQI was alpha = 0.79. Of the PSQI subscales, the subjective sleep quality correlated most strongly with the other sleep instruments (r between 0.68 and 0.77). In total, 69.2% of the sample were poor sleepers; the effect size of the difference between the PSQI total scores of the patients and a general population sample was d = 0.83. Female patients experienced more sleep problems than male patients (d = -0.49), and younger patients (<60 years) reported more sleep problems than older patients (>= 60 years) (d = 0.21). Conclusions: The PSQI can be recommended for use in clinical practice since its sub-dimensions provide detailed information on the sleep situation of cancer patients.