Validity and reliability of the Taiwanese version of the Pittsburgh Sleep Quality Index in cancer patients

Background: Sleep disturbance remains a common symptom among cancer patients. Assessment of sleep disturbance in cancer patients is hindered by infrequent use of standardized tools for sleep management. Objectives: The purposes of this study were to validate the Taiwanese version of the Pittsburgh Sleep Quality Index (PSQI-T) and to determine detection cut-off points in cancer patients. Design: A cross-sectional and descriptive correlational design. Participants: A sample of 205 Taiwanese patients with various cancer diagnoses. Methods: The survey included the Pittsburgh Sleep Quality Index-Taiwanese version, the MD Anderson Symptom Inventory-Taiwanese version, the Brief Fatigue Inventory-Taiwanese version, the seven-day sleep log, and Manual of Mental Disorders, Fourth Edition. Results: The internal consistency Cronbach's alpha for the PSQI was 0.79. Test-retest reliability was 0.91 for the global score over a 20- to 28-day interval in a sample of 16 patients. Construct validity was established by a significant relationship of the PSQI-T global score to the total symptom severity score and the fatigue severity score. Convergent validity was examined by correlating the PSQI-T scores and scores of the DSM-IV and scores on the seven-day sleep log. Known-group validity was established by comparing PSQI-T scores for patients having low fatigue levels and those having high fatigue levels. Receiver-operating characteristic (ROC) curves were used to determine the detection cut-off points. Conclusions: We found that a PSQI-T global score of 8 generates the best sensitivity and specificity for measuring sleep disturbance in cancer patients. The PSQI-T is a reliable, valid, and sensitive instrument for measuring sleep quality among Taiwanese cancer patients.