Psychometric performance and responsiveness of the functional outcomes of sleep questionnaire and sleep apnea quality of life instrument in a randomized trial: the HomePAP study

Martha E Billings; Carol L Rosen; Dennis Auckley; Ruth Benca; Nancy Foldvary-Schaefer; Conrad Iber; Phyllis C Zee; Susan Redline; Vishesh K Kapur

doi:10.5665/sleep.4262

Psychometric performance and responsiveness of the functional outcomes of sleep questionnaire and sleep apnea quality of life instrument in a randomized trial: the HomePAP study

Sleep. 2014 Dec 1;37(12):2017-24. doi: 10.5665/sleep.4262.

Authors

Martha E Billings¹, Carol L Rosen², Dennis Auckley³, Ruth Benca⁴, Nancy Foldvary-Schaefer⁵, Conrad Iber⁶, Phyllis C Zee⁷, Susan Redline⁸, Vishesh K Kapur¹

Affiliations

¹ UW Medicine Sleep Center, Division of Pulmonary Critical Care, University of Washington, Seattle, WA.
² Case Western Reserve University, School of Medicine, Cleveland, OH: Rainbow Babies and Children's Hospital, University Hospitals, Case Medical Center, Cleveland, OH.
³ Case Western Reserve University, School of Medicine, Cleveland, OH: Center for Sleep Medicine, Division of Pulmonary, Critical Care and Sleep Medicine, MetroHealth Medical Center, Cleveland, OH.
⁴ Department of Psychiatry, University of Wisconsin, Madison, WI.
⁵ Case Western Reserve University, School of Medicine, Cleveland, OH: Cleveland Clinic, Cleveland, OH.
⁶ Hennepin County Medical Center, University of Minnesota, Minneapolis, MN.
⁷ Northwestern University, Feinberg School of Medicine, Chicago, IL.
⁸ Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA.

Abstract

Study objectives: Measures of health-related quality of life (HRQL) specific for sleep disorders have had limited psychometric evaluation in the context of randomized controlled trials (RCTs). We investigated the psychometric properties of the Functional Outcomes of Sleep Questionnaire (FOSQ) and Sleep Apnea Quality of Life Instrument (SAQLI). We evaluated the FOSQ and SAQLI construct and criterion validity, determined a minimally important difference, and assessed for associations of responsiveness to baseline subject characteristics and continuous positive airway pressure (CPAP) adherence in a RCT population.

Design: Secondary analysis of data collected in a multisite RCT of home versus laboratory-based diagnosis and treatment of obstructive sleep apnea (HomePAP trial).

Participants: Individuals enrolled in the HomePAP trial (n = 335).

Interventions: N/A.

Measurement and results: The FOSQ and SAQLI subscores demonstrated high reliability and criterion validity, correlating with Medical Outcomes Study 36-Item Short Form Survey domains. Correlations were weaker with the Epworth Sleepiness Scale (ESS). Both the FOSQ and SAQLI scores improved after 3 mo with CPAP therapy. Averaging 4 h or more of CPAP use was associated with an increase in the FOSQ beyond the minimally important difference. Baseline depressive symptoms and sleepiness predicted FOSQ and SAQLI responsiveness; demographic, objective obstructive sleep apnea (OSA) severity and sleep habits were not predictive in linear regression.

Conclusions: The FOSQ and SAQLI are responsive to CPAP intervention, with the FOSQ being more sensitive to differences in CPAP adherence than the SAQLI. These instruments provide unique information about health outcomes beyond that provided by changes in physiological measures of OSA severity (apnea-hypopnea index).

Clinical trial information: Portable Monitoring for Diagnosis and Management of Sleep Apnea (HomePAP) URL: http://clinicaltrials.gov/show/NCT00642486. NIH clinical trials registry number: NCT00642486.

Keywords: health-related quality of life; psychometrics; sleep apnea.

Publication types

Randomized Controlled Trial
Research Support, Non-U.S. Gov't

MeSH terms

Continuous Positive Airway Pressure*
Female
Humans
Male
Middle Aged
Patient Compliance
Psychometrics
Quality of Life*
Reproducibility of Results
Sleep / physiology*
Sleep Apnea, Obstructive / physiopathology*
Sleep Apnea, Obstructive / psychology*
Sleep Apnea, Obstructive / therapy
Surveys and Questionnaires*
Treatment Outcome

Associated data

ClinicalTrials.gov/NCT00642486