The relationship of subjective sleep quality, pain, and quality of life in advanced cancer patients.

STUDY OBJECTIVES Cancer patients have been reported to complain about poor quality of sleep. This study evaluated the quality of sleep in this group, utilizing demographic data and clinical features of the cancers as assessment criteria. A secondary aim was to evaluate the correlation between the self-rated questionnaire for the quality of sleep with other instruments used in measuring pain and quality of life. DESIGN A total of 102 patients with stage IV cancer completed the study and were subsequently followed for up to 10 months. Self-rated questionnaires were administered for the evaluation of quality of sleep (PSQI), quality of life Medical Outcomes Study 12-item short-form (SF-12) questionnaire, the Mental Component Summary (MSC) and the Physical Component Summary (PCS), and pain (VAS Pain). The mediation analysis model was also used to evaluate how quality of life can influence the quality of sleep through its relation to pain, the performance status of patients and analgesics (Opioids). PATIENTS The mean age of the study participants was 62.8 (range: 26.0-87.0) years old. The majority (70.6%) of the patients presented with ECOG score between 2 and 3 and with metastasis (58.8%). RESULTS Mean Global Sleep Quality score was 12.0+/-4.6. The use of the PSQI questionnaire in cancer patients demonstrated that these subjects were prone to sleep poor quality. However, the various demographic variables and clinical features of the cancers did not affect quality of sleep. Global Sleep Quality scores from the PSQI correlated with the scores obtained from the SF-12 questionnaire and with the VAS Pain results, indicating a relationship between quality of sleep, quality of life and pain. However, only the SF-12 questionnaire had predictive value on quality of sleep. Mediation analysis showed that quality of life influences quality of sleep both directly and indirectly by its effect on pain. In addition, some of the effect of quality of life on sleep quality was mediated by the use of opioids. CONCLUSIONS Quality of sleep in patients suffering from stage IV cancer was significantly decreased. Demographic data and clinical variables of cancers did not affect the PSQI Global Sleep Quality score. The use of the mediation model also provides evidence that quality of sleep, quality of life, pain, and opioids are strictly correlated each other.