STUDY OBJECTIVES: After nasal continuous positive airway pressure (nCPAP) treatment, several symptoms such as hypersomnolence, daytime fatigue, and impaired concentration improve in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS). A variability of perception of pretreatment sleepiness (response-shift phenomenon) experienced in OSAHS patients before and after nCPAP treatment may reflect informative shifts in an individual's internal standards, in values and priorities, or in the conceptualization of perceived sleepiness. The objective of this study is to determine whether there is a response shift in perceptions of pretreatment sleepiness before and after nCPAP treatment in patients with OSAHS. We investigated the response shift in Epworth Sleepiness Scale scores before and after nCPAP.
DESIGN: Thirty-one consecutive OSAHS patients filled out the subjective ESS before nCPAP treatment (Pre-ESS). After a mean of about 10 months of nCPAP treatment, the patients filled out the ESS again, which was designated as the Post-ESS. Then they were asked to complete the scale again, recalling sleepiness before nCPAP treatment (Response Shift-Pre-ESS). The control group consisted of 11 patients with OSAHS who had not yet received nCPAP treatments and were matched for age, body mass index, and respiratory disturbance index.
SETTING: University Hospital in, Japan.
INTERVENTIONS: N/A.
MEASUREMENTS AND RESULTS: There was a significant response shift in ESS scores before and after nCPAP treatment (Pre-ESS: 8.5 [95% Confidence interval [CI], 7.1-9.9] vs Response Shift-Pre-ESS: 11.1 [95% CI, 9.5-12.8], P < .002). A significant number of patients (P < .02) had not recognized the degree of sleepiness experienced before treatment until after they had received nCPAP treatment. Eight had pretreatment ESS scores > or = 11 and 18 had posttreatment ESS scores > or = 11 on the Response Shift-Pre-ESS. In the control group, ESS did not change significantly from the first to the second testing performed before nCPAP treatment (first ESS, 8.8 [95% CI, 5.3-12.3]; second ESS, 8.3 [95% CI, 4.7-11.8]: P = .95).
CONCLUSIONS: Response shifts should be taken into consideration when explaining factors underlying individual differences in susceptibility to daytime sleepiness.
