The Pittsburgh Sleep Quality Index-2: The validity of a two-item sleep quality screener in Brazilian adults

Abstract Background: Several instruments are available to assess sleep quality, including the 19-item Pittsburgh Sleep Quality Index (PSQI). As shorter measures may be desirable for use in clinical settings or population-based research, we evaluated the validity of a 2-item sleep quality screener, the PSQI-2. Methods: The PSQI-2 inquiries about sleep duration and subjective sleep quality over the past 30 days, scoring each from 0 ("very good"; > 7h of sleep) to 3 ("very bad"; < 5h of sleep). The sum of the two items generates a score from 0 to 6; the higher the score, the worse the sleep quality. This study was conducted with 1,762 adults in a population-based household survey with stratified sampling between October and December 2020 in Brazil. Concurrent validity was assessed using the full PSQI as the reference test. Results: As PSQI-2 scores increased from 0 to 6, a substantial increase has been found in the prevalence of individuals with poor sleep quality (p <0.05). The PSQI-2 had excellent internal consistency (α = 0.94 and ω = 0.85) and known-group validity, with higher scale scores found in individuals with symptoms of depression and anxiety. Considering PSQI > 5 (poor sleep quality) as a reference, the best cut-off point of the PSQI-2 score was > 2, with a sensitivity of 77.9% and specificity of 73.8%. The concurrent validity revealed acceptable performance of the PSQI-2 for the PSQI > 5 and > 7, and exceptional performance for the PSQI > 10. Conclusion: The PSQI-2 presents good/excellent validity evidence for screening sleep quality in a sample of Brazilian adults.