Validity and Reliability of the Greek Version of Pittsburgh Sleep Quality Index in Chronic Non-Specific Low Back Pain Patients

The purpose of this study was to investigate psychometric properties of the Greek translation of Pittsburgh Sleep Quality Index (GR-PSQI) in a Greek chronic non-specific low back pain (CNSLBP) sample, thus, providing insight on its clarity and acceptability as a widely used sleep assessment tool in clinical practice. Asymptomatic volunteers (n = 73) and CNSLBP volunteers (n = 47), participated in the study. For the assessment of construct validity, the known-groups method was used. Thus, all the participants (asymptomatic and CNSLBP) completed the GR-PSQI. For the assessment of concurrent validity, the CNSLBP participants additionally completed the following validated questionnaires for depression, insomnia and sleep quality: Beck Depression Inventory Questionnaire (BDI), Insomnia Severity Index (ISI), and Sleep Quality Numeric Rating Scale (SQNRS). For the assessment of test–retest reliability, the CNSLBP participants completed the GR-PSQI a second time, one week after the first time. The results showed excellent test–retest reliability (ICC = 0.969, SEM = 0.90, SDD = 2.49%) and internal consistency (Cronbach α = 0.985), moderate to good concurrent validity (from r = 0.556 to r = 0.860) among PSQI, BDI, SQNRS, and ISI, as well as excellent construct validity (p = 0.000) between the two groups. The Greek translation of PSQI could be a valuable tool for Greek healthcare professionals in both clinical and research environments.