Health Preference Measures in Patients with Obstructive Sleep Apnea Syndrome Undergoing Continuous Positive Airway Pressure Therapy: Data from a Randomized Trial

An empirical comparison of sleep-specific versus generic quality of life instruments among Australians with sleep disorders

PURPOSE

In Australian adults diagnosed with a sleep disorder(s), this cross-sectional study compares the empirical relationships between two generic QoL instruments, the EuroQoL 5-dimension 5-level (EQ-5D-5L) and ICEpop CAPability measure for Adults (ICECAP-A), and three sleep-specific metrics, the Epworth Sleepiness Scale (ESS), 10-item Functional Outcomes of Sleep Questionnaire (FOSQ-10), and Pittsburgh Sleep Quality Index (PSQI).

METHODS

Convergent and divergent validity between item/dimension scores was examined using Kendall's Tau-B correlation, with correlations below 0.30 considered weak, between 0.30 and 0.50 moderate and those above 0.50 strong (indicating that instruments were measuring similar constructs). Exploratory factor analysis (EFA) was conducted to identify shared underlying constructs.

RESULTS

A total of 1509 participants (aged 18-86 years) were included in the analysis. Convergent validity between dimensions/items of different instruments was weak to moderate. A 5-factor EFA solution, representing 'daytime dysfunction', 'fatigue', 'wellbeing', 'physical health', and 'perceived sleep quality', was simplest with close fit and fewest cross-loadings. Each instrument's dimensions/items primarily loaded onto their own factor, except for the EQ-5D-5L and PSQI. Nearly two-thirds of salient loadings were of excellent magnitude (0.72 to 0.91).

CONCLUSION

Moderate overlap between the constructs assessed by generic and sleep-specific instruments indicates that neither can fully capture the complexity of QoL alone in general disordered sleep populations. Therefore, both are required within economic evaluations. A combination of the EQ-5D-5L and, depending on context, ESS or PSQI offers the broadest measurement of QoL in evaluating sleep health interventions.

Content Comparison of Quality-of-Life Instruments Used in Economic Evaluations of Sleep Disorder Interventions: A Systematic Review

BACKGROUND

Assessment of quality of life (QoL) in people living with sleep disorders using questionnaires is necessary to compare intervention benefits. Knowledge of the content and concepts covered by specific QoL instruments is essential to determine which instruments are best suited for conducting economic evaluations of sleep-related interventions.

OBJECTIVES

This review aims to identify the QoL instruments that have been applied in economic evaluations of sleep disorder interventions and compare their conceptual overlap and content coverage using the framework of the International Classification of Functioning, Disability and Health (ICF).

METHODS

A systematic review of full economic evaluations in sleep published in peer-reviewed journals from conception to 30 May, 2023 was conducted. MEDLINE, PsychInfo, ProQuest, Cochrane, Scopus, CINAHL, Web of Science and Emcare were searched for eligible studies. Studies incorporating either generic or sleep-specific QoL instruments as the primary or secondary measures of effectiveness within a full economic evaluation were included. Quality appraisal against the JBI Critical Appraisal Checklist for Economic Evaluations and EURONHEED checklists and mapping of QoL items to ICF categories were performed by two reviewers, with a third helping settle any potential differences.

RESULTS

Sixteen instruments were identified as having been used in sleep health economic evaluations. The EQ-5D-3L, Epworth Sleepiness Scale, and Insomnia Severity Index were the most widely used, but the latter two are predominantly diagnostic tools and not specifically designed to guide economic evaluations. Other instruments with broader ICF content coverage have been least used, and these include the Sleep Apnea Quality of Life Index, Functional Outcomes of Sleep Questionnaire, 15 Dimensions, Short-Form 6 Dimensions, 12-item Short Form Survey, 36-item Short Form Survey and the GRID Hamilton Rating Scale for Depression.

CONCLUSIONS

This study provides an overview of current QoL instruments used in economic evaluations of sleep with respect to their content coverage. A combination of generic and sleep-specific instruments with broader ICF content coverage is recommended for such evaluations.

Cost-Utility Analysis of Continuous Positive Airway Pressure Therapy Compared With Usual Care for Obstructive Sleep Apnea in the Public Health System in Brazil

OBJECTIVES

This study aimed to conduct a cost-utility analysis of continuous positive airway pressure (CPAP) therapy compared with usual care as treatment of moderate to severe cases of obstructive sleep apnea (OSA) in Brazil, where decentralized policies of CPAP provision are in place.

METHODS

Markov cohort model comparing CPAP therapy with usual care, that is, no specific treatment for OSA, for moderate to severe cases was used. The payer perspective from the Unified Health System, Brazil, was adopted. Effectiveness parameters and costs related to health states were informed by literature review. Resource use related to CPAP therapy was defined by specialists and costs informed by recent purchase and leasing contracts. Incremental cost-effectiveness ratios were generated for purchase and leasing contracts to reflect current practices. A conservative willingness-to-pay threshold was set at 1 gross domestic product per capita per quality-adjusted life-year (QALY) (Brazilian reais [BRL] 40 712/QALY). Uncertainties were explored in deterministic and probabilistic sensitivity analyses.

RESULTS

Incremental cost-effectiveness ratio for the purchase modality was 8303 BRL/QALY and for leasing 45 192 BRL/QALY. Considering the adopted willingness-to-pay threshold, provision of CPAP by the purchase modality was considered cost-effective but not the leasing modality. The parameter related to the greatest uncertainty was the reduction in the risk of having a stroke attributable to CPAP. Probabilistic analysis confirmed the robustness of results.

CONCLUSIONS

CPAP therapy is a cost-effective alternative compared with usual care for moderate to severe OSA for the purchase modality. These results should help underpinning the decision making related to a uniform policy of CPAP provision across the country.

Use of the visual analogue scale for health state valuation: a scoping review

OBJECTIVES

The visual analogue scale (VAS) has been used in the context of health and healthcare for various purposes, for example, to measure pain and to provide a single-index measure of health-related quality of life (HRQoL). This scoping review aims to describe how the VAS has been used for health state valuation in the published literature.

METHODS

The search was carried out in Medline, Web of Science and PsycInfo. The findings of the included articles were tabulated and presented descriptively using frequencies and proportions.

RESULTS

The database search yielded 4856 unique articles, out of these, 308 were included. In 83% of the articles, the main purpose for using a VAS was to value health states. The two most common perspectives when valuing health states with a VAS were hypothetical (44%) and own health (34%). Some (n = 14) articles used the VAS in the context of economic evaluations, including calculating quality-adjusted life years (QALYs). A large variation in the design of the VAS was found, including the description of the lower and upper anchors. Advantages and disadvantages with using a VAS were mentioned in 14% of the included articles.

CONCLUSION

The VAS has been a common method for valuing health states, both as a stand-alone method and in combination with other valuation methods. Despite its widespread use, the design of the VAS has been inconsistent which makes comparison of results across studies challenging. Further research on the role of using the VAS in economic evaluations is warranted.

Dynamics of Circulating CD14/CD16 Monocyte Subsets in Obstructive Sleep Apnea Syndrome Patients upon Hypoglossal Nerve Stimulation

Background: Obstructive sleep apnea syndrome (OSAS) is a widespread respiratory disease that is associated with recurrent breathing intermissions at night. The corresponding oxidative stress triggers a low-grade systemic inflammation which leads to alterations of different immune cells in the peripheral blood. The current standard treatment for OSAS is continuous positive airway pressure (CPAP), whereas hypoglossal nerve stimulation (HNS) has been established as a second-line treatment option for CPAP failure. The aim of the study was to investigate the influence of HNS for OSAS patients on the distribution and differentiation of circulating monocyte subsets in connection with the clinical parameters. Materials and Methods: Therefore, a detailed analysis of the distribution of CD14/CD16 characterized monocyte subsets in the peripheral blood of OSAS patients before and after HNS therapy was performed by flow cytometry. Furthermore, values of BMI (body mass index), ODI (oxygen desaturation index), and ESS (Epworth Sleepiness Scale) were measured. Results: These OSAS patients significantly improved AHI and ESS scores under HNS. In addition, HNS revealed the potential to ensure normal distributions of blood monocyte subsets and even improved the monocyte dynamics in selected OSAS patients, but there were no significant correlations with AHI, ODI, HNS usage, and daytime sleepiness. Conclusions: We conclude that HNS-related positive effects on the oxygenation of the peripheral blood as well as affect the distribution of circulating monocyte subsets, but clinical OSAS correlations are missing. Far more individual clinical, cellular and molecular factors are involved in this sensitive and complex regulatory network and have to be elucidated in further studies.

Reconstitution of Monocyte Subsets and PD-L1 Expression but Not T Cell PD-1 Expression in Obstructive Sleep Apnea Patients upon PAP Therapy

Obstructive sleep apnea (OSA) is characterized by nocturnal breathing intermissions resulting in oxidative stress and eventually, a low-grade systemic inflammation. The study aimed to investigate the impact of positive airway pressure (PAP) therapy on the inflammatory milieu as measured by monocyte and T cell phenotypic alterations. Participants were assessed for their OSA severity before PAP therapy and about six months later, including patient-reported outcome and therapy usage by telemetry readout. The distributions of the CD14/CD16-characterized monocyte subsets as well as the CD4/CD8-characterized effector T cell subsets with regard to their PD-1 and PD-L1 expression were analyzed by flow cytometry from blood samples. Data of 25 patients revealed a significant reconstitution of the monocyte subset distribution and a decrease in PD-L1 expression on pan-monocytes and CD8⁺ T cells without an association to initial AHI and overweight. The PD-1 expression was still increased on T cell subsets, especially on CD4⁺ TH17/22 cells. We conclude that PAP therapy might have a rapid effect on the monocyte phenotype and overall PD-L1 expression levels. However, T cell immune alterations especially on TH17/22 cells persist longer, indicating an ongoing disturbance of the adaptive immune system.