Psychometric properties of the Ethos Brief Index (EBI) using factorial structure and Rasch Analysis among patients with obstructive sleep apnea before and after CPAP treatment is initiated

Abstract

Background Continuous positive airway treatment (CPAP) is the recommended treatment for patients with obstructive sleep apnea (OSA). Outcome measures often focus on clinical and/or self-rated variables related to the medical condition. However, a brief validated instrument focusing on the whole life situation (i.e., ethos) suitable for clinical practice is missing. The aim of this study was to investigate factorial structure, categorical functioning of the response scale, and differential item functioning across sub-populations of the Ethos Brief Index (EBI) among patients with obstructive sleep apnea (OSA) before and after initiation of continuous positive airway pressure (CPAP). Methods A prospective design, including 193 patients with OSA (68% men, 59.66 years, SD 11.51) from two CPAP clinics, was used. Clinical assessment and overnight respiratory polygraphy were used to diagnose patients. Questionnaires administered before and after 6 months of CPAP treatment included EBI, Epworth Sleepiness Scale (ESS), Hospital Anxiety and Depression Scale, and global perceived health (initial item in SF-36). The validity and reliability of the EBI were investigated using Rasch and confirmatory factor analysis models. Measurement invariance, unidimensionality, and differential item functioning across gender groups, Apnea-Hypopnea Index, and ESS groups were assessed. Results The reliability of the EBI was confirmed using composite reliability and Cronbach’s alpha. The results supported unidimensionality of the EBI in confirmatory factor analysis and the Rasch model. No differential item functioning was found. A latent profile analysis yielded two profiles of patients with low ( n = 42) and high ( n = 151) ethos. Patients in the low ethos group were younger and had higher depression scores, lower perceived health, and higher body mass index. Conclusions The EBI is a valid tool with robust psychometric properties suitable for use among patients with OSA before and after treatment with CPAP is initiated. Future studies should focus on its predictive validity.

The ethos brief index—validation of a brief questionnaire to evaluate wellness based on a holistic perspective in patients with restless legs syndrome

“…In addition, no DIF was identified for either sex, age, or any of the RLS-related variables (i.e., insomnia, daytime sleepiness, RLS severity, or RLS-related QoL), which makes EBI a short and valid alternative to RLS-specific and generic QoL instruments. The unidimensional structure of the EBI found in both general [16,17] and OSA populations [21] was also supported in the present study by results from both the CFA (i.e., explaining 61.5% of the variance) and Rasch analysis.…”

“…The items are scored on a scale from 0 (very bad) to 10 (very good). In the version tested in patients with obstructive sleep apnea [21], as well as in the present study, item 9 worded "I am satisfied with my total life situation" was deleted to decrease the number of items. The other eight items are summarized, yielding a total score of 0-80.…”

“…Since theory on the construct already exists [16,17,21], the structural validity of the EBI was assessed by CFA using the diagonally weighted least squares estimator. Several indices were used to test the unidimensional structure of the EBI: comparative fit index (CFI), Tucker-Lewis index (TLI), root mean square error of approximation (RMSEA), and standardized root mean square residual (SRMR).…”

“…The 67-item Ethos Toward Wellness Questionnaire (EtWeQ) [16,17] is grounded in theory [18][19][20] and has shown promising validity in a healthy population [16,17], but it has not yet been used in people with RLS. One problem is that the EtWeQ is extensive, but the last part of the EtWeQ, the Ethos Brief Index (EBI), has proven valid in patients with obstructive sleep apnea (OSA) [21]. The EBI could, if found valid and reliable also in an RLS population, be a comprehensive tool for clinicians and researchers to evaluate Ethos before and after treatment initiation and could work as a holistic tool to strengthen the patient's perspective during shared decisionmaking [22,23].…”

Communication during the initial visit to a CPAP clinic Practitioners’ experiences of facilitators and barriers when talking to patients with obstructive sleep apnea

“…after several weeks of treatment), as side‐effects tend to vary and patients respond differently to interventions, which might affect habit development (Ulander et al., 2014 ). The same instruments complemented with, for instance, Calgary Sleep Apnea Quality of Life Index (Flemons & Reimer, 2002 ) and Ethos Brief Index (Broström et al., 2019 ) might be applied to evaluate mediators and moderators for CPAP adherence, but also to establish whether patient‐centred communication during clinical visits facilitates the patient's adherence to CPAP, or whether a specific therapeutic orientation (e.g. psychological) is required.…”