Effect of adherence on daytime sleepiness, fatigue, depression and sleep quality in the obstructive sleep apnea/hypopnea syndrome patients undertaking nasal continuous positive airway pressure therapy

Abstract

Objectives: The aims of this study were to describe changes in day- and nighttime symptoms and the adherence to nasal continuous positive airway pressure (nCPAP) during the first 3-month nCPAP therapy among newly diagnosed patients with obstructive sleep apnea/hypopnea syndrome (OSAS) and to identify the effect of adherence on the changes in day- and nighttime symptoms during the first 3 months.

Methods: Newly diagnosed OSAS patients were consecutively recruited from March to August 2013. Baseline clinical information and measures of the Epworth Sleepiness Scale (ESS), Fatigue Severity Scale (FSS), Zung's Self-Rating Depression Scale (SDS) and the Pittsburgh Sleep Quality Index (PSQI) at baseline and the end of 3rd, 6th, 9th and 12th week of therapy were collected. Twelve weeks' adherence was calculated as the average of each 3-week period. Mixed model was used to explore the effect of adherence to nCPAP therapy on ESS, FSS, SDS and PSQI in each 3-week phase.

Results: Seventy-six patients completed the 12-week follow-up. The mixed-effects models showed that under the control of therapy phase adherence in the range of <4 hours per night, using nCPAP could independently improve daytime sleepiness, in terms of ESS (coefficient, [95% confidence interval] unit; -4.49 [-5.62, -3.36]). Adherence at 4-6 hours per night could independently improve all variables of day- and nighttime symptoms included in this study, namely ESS -6.69 (-7.40, -5.99), FSS -6.02 (-7.14, -4.91), SDS -2.40 (-2.95, -1.85) and PSQI -0.20 (-0.52, -0.12). Further improvement in symptoms could be achieved at ≥6 hours per night using nCPAP, which was ESS -8.35 (-9.26, -7.44), FSS -10.30 (-11.78, -8.83), SDS -4.42 (-5.15, -3.68) and PSQI -0.40 (-0.82, -0.02). The interaction between adherence level and therapy phase was not significant in day- and nighttime symptoms.

Conclusion: The effect of adherence on the above-mentioned symptoms is stable through the first 3 months. Under the control of therapy phase, the nCPAP therapy effectively improves day- and nighttime symptoms with ≥4 hours adherence, and the patients can achieve a further improvement with ≥6 hours adherence.

Keywords: Epworth Sleepiness Scale; Fatigue Severity Scale; OSAS; Zung’s Self-Rating Depression Scale; nCPAP; the Pittsburgh Sleep Quality Index.

Figure 1

The crude relationship between adherence and ESS and FSS scores in each 3-week period. Notes: Each point represents one study subject. ESS, Epworth Sleepiness Scale (0–24, higher score indicated sleepier); FSS, Fatigue Severity Scale (9–63, higher score indicated more fatigue). Abbreviations: h, hour; wk, weeks.

Figure 2

The crude relationship between adherence and SDS and PSQI scores in each 3-week period. Notes: Each point represents one study subject. SDS, Zung’s Self-Rating Depression Scale (20–80, higher score indicated more depressed) and PSQI, The Pittsburgh Sleep Quality Index (0–21, higher score indicated lower sleep quality). Abbreviations: h, hour; wk, weeks.

Figure 3

Adjusted relationships between adherence range and the changes in ESS, FSS, SDS and PQSI scores from baseline within each 3-week period during first 3 months of nCPAP therapy. Notes: (A) Adjusted relationship between the change in ESS score from baseline and adherence range within each 3-week period during first 3 months of nCPAP therapy; the mean of adjusted ESS score at baseline was 12.66. (B) Adjusted relationship between the change in FSS score from baseline and adherence range within each 3-week period during first 3 months of nCPAP therapy; the mean of adjusted FSS score at baseline was 44.40. (C) Adjusted relationship between the change in SDS score from baseline and adherence range within each 3-week period during first 3 months of nCPAP therapy among males; the mean of adjusted SDS score at baseline was 36.55. (D) Adjusted relationship between the change in PSQI score from baseline and adherence range within each 3-week period during first 3 months of nCPAP therapy among males; the mean of adjusted PSQI score at baseline was 4.73. ESS, Epworth Sleepiness Scale (0–24, higher score indicated sleepier); FSS, Fatigue Severity Scale (9–63, higher score indicated more fatigue); SDS, Zung’s Self-Rating Depression Scale (20–80, higher score indicated more depressed); PSQI, The Pittsburgh Sleep Quality Index (0–21, higher score indicated lower sleep quality). Abbreviations: nCPAP, nasal continuous positive airway pressure; h, hours; wk, weeks.