Assessing the reliability and validity of sleep assessments in patients seeking metabolic and bariatric surgery.

BACKGROUND

More than 80% of patients seeking metabolic and bariatric surgery (MBS) report disturbance in sleep function. No studies have assessed the psychometric properties of sleep measures in MBS samples.

OBJECTIVES

This study assessed the reliability and validity of the Pittsburgh Sleep Quality Index (PSQI) and the Insomnia Severity Index (ISI) in a large sample of patients seeking MBS.

SETTING

Two academic medical centers.

METHODS

Measures of sleep (PSQI and ISI) and psychological functioning, including the Quick Inventory of Depressive Symptomatology (QIDS), were administered presurgically. Internal consistency was assessed with mean inter-item correlations and item-total correlations. Construct validity was assessed using confirmatory factor analyses (CFAs) based on models identified in the literature and by measuring convergent and discriminant validity.

RESULTS

Participants (N = 939) were primarily female (83.4%) with a mean age of 41.7 (SD = 11.5) years and mean body mass index (BMI) of 47.5 kg/m2 (SD = 8.5). CFAs indicated excellent fit for 2-factor solutions for the PSQI and ISI. Internal consistency for the PSQI and ISI were acceptable. Convergent validity was demonstrated by large correlations between the PSQI and ISI (r = .80, p < .001), and moderate correlation between the PSQI, ISI, and QIDS (rs > .50, ps < .001). The PSQI and ISI were moderately correlated with QIDS items assessing sleep function (P < .001), but correlations with items assessing appetite change were small (r < .10), demonstrating good discriminant validity.

CONCLUSIONS

Results support the reliability and validity of the PSQI and ISI for patients undergoing MBS.