Objective: To determine the minimal clinically important difference (MCID) and minimal detectable change (MDC) of the Standardized List Evaluating Apnea (SLEAP) and evaluate its psychometric properties using item response theory (IRT).

Study design: Prospective cohort study.

Settings: Tertiary referral center.

Methods: This study included 379 adults with obstructive sleep apnea (OSA). MCID and MDC were calculated using a distribution-based approach. The IRT analysis assessed the difficulty and discrimination of the 6-step SLEAP scale.

Results: The IRT analysis showed that most items evenly described quality of life (QoL) limitations, with minor over- or underestimation in specific items.The MCID of SLEAP was 12 points, and the MDC was 12.2 points. For all the items in the questionnaire, the discrimination ability ranged from moderate to perfect, indicating strong capacity to differentiate QoL levels. The SLEAP scale performed best around the average QoL level in this sample.

Conclusion: The SLEAP scale demonstrated an MCID of 12 points, robust psychometric properties, and strong discrimination ability. It effectively measures QoL changes in patients with OSA and serves as a reliable screening tool in clinical and research settings.