Associations of self-efficacy and outcome expectancy with adherence to continuous positive airway pressure therapy in Japanese patients with obstructive sleep apnea.

Objective: To examine the associations of self-efficacy and outcome expectancy with adherence to continuous positive airway pressure (CPAP) therapy among Japanese men with obstructive sleep apnea (OSA) using objective adherence data for CPAP therapy. Methods: We conducted a retrospective study of 497 Japanese men with OSA who were receiving CPAP therapy. Good adherence was defined as CPAP use of ≥4 hours per night for ≥70% of nights. Logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for the associations of good adherence to CPAP therapy with self-efficacy and outcome expectancy (measured with the CPAP Self-Efficacy Questionnaire for Sleep Apnea in Japanese). The models were adjusted for age, duration of CPAP therapy, body mass index, apnea-hypopnea index, Epworth Sleepiness Scale score, and comorbidities (diabetes mellitus and hypertension). Results: In total, 53.5% of participants had good adherence to CPAP therapy. The mean CPAP use was 5.18±1.53 hours/night. After adjusting for related factors, we found significant associations of good adherence to CPAP therapy with self-efficacy scores (OR, 1.10; 95% CI, 1.05-1.13; p<0.001) and outcome expectancy scores (OR, 1.10; 95% CI, 1.02-1.15; p=0.007). Conclusions: Our results indicate that self-efficacy and outcome expectancy are associated with good adherence to CPAP therapy among Japanese men with OSA.

Associations of diabetes mellitus and hypertension with adherence to continuous positive airway pressure therapy in male patients with obstructive sleep apnea.

Methods: We conducted a retrospective study among 497 male patients with OSA on CPAP therapy. Participants with pretreatment Apnea-Hypopnea Index (AHI) data based on overnight polysomnographic recordings completed a questionnaire. Adherence data for CPAP therapy were collected using a smart card system. We classified CPAP use of ≥4 hours per night and ≥70% of nights as good adherence; other CPAP use was categorized as poor adherence. Logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for poor adherence to CPAP therapy in the hypertension and diabetes mellitus groups, compared with the no comorbidity group, adjusting for body mass index, duration of CPAP therapy, AHI, and Epworth Sleepiness Scale score. Results: In the no comorbidity, hypertension, and diabetes mellitus groups, 43.4%, 44.7%, and 56.0%, respectively, had poor adherence to CPAP therapy. Being in the diabetes mellitus group was significantly associated with poor adherence to CPAP therapy (OR=1.86, 95% CI: 1.18-2.92, p=0.007); there was no association for the hypertension group. Conclusion: Our results indicate that comorbidity of diabetes mellitus is associated with poor adherence to CPAP therapy in male patients with OSA.

Development and evaluation of a self-efficacy instrument for Japanese sleep apnea patients receiving continuous positive airway pressure treatment.

The purpose of this study was to develop and evaluate a self-efficacy instrument for Japanese obstructive sleep apnea (OSA) patients treated with continuous positive airway pressure (CPAP). Analyzed subjects were 653 Japanese OSA patients (619 males and 34 females) treated with CPAP at a sleep laboratory in a respiratory clinic in a Japanese city. Based on Bandura's social cognitive theory, the CPAP Self-Efficacy Questionnaire for Sleep Apnea in Japanese (CSESA-J) was developed by a focus group of experts, using a group interview of OSA patients for the items of two previous self-efficacy scales for Western sleep apnea patients receiving CPAP treatment. CSESA-J has two subscales, one for self-efficacy and the other for outcome expectancy, and consists of a total of 15 items. Content validity was confirmed by the focus group. Confirmatory factor analysis showed that the factor loadings of self-efficacy and outcome expectancy were 0.47-0.76 and 0.41-0.92, respectively, for the corresponding items. CSESA-J had a significant but weak positive association with the General Self-Efficacy Scale, and a strong positive association with "Self-efficacy scale on health behavior in patients with chronic disease." Cronbach's alpha coefficient was 0.85 for the self-efficacy subscale and 0.89 for the outcome expectancy subscale. The intraclass correlation coefficient using data from the first and second measurements with CSESA-J for a subset of 130 subjects was 0.93 for the self-efficacy and outcome expectancy subscales. These results support CSESA-J as a reliable and valid instrument for measuring the self-efficacy of Japanese OSA patients treated with CPAP. Further studies are warranted to confirm validity for female OSA patients and generalizability.

Incidence of chronic obstructive pulmonary disease, and the relationship between age and smoking in a Japanese population.

BACKGROUND: Accurately evaluating a risk of chronic obstructive pulmonary disease (COPD) requires a large-scale longitudinal study using a standard criterion for diagnosing COPD. There have been only a few such follow-up studies in Europe and no reports in Asia. We estimated the incidence rate and incidence rate ratio (IRR) of age and smoking for COPD in a Japanese population using the diagnosis criterion of the Global Initiative for Chronic Obstructive Lung Disease guidelines. METHODS: Subjects were 17,106 participants aged 25-74 years during health check-ups including spirometry from April 1997 through March 2005 in Japan. Total follow-up of participants were 47,652 person-years in males and 25,224 person-years in females. The IRR of age and smoking was estimated using Cox proportional hazard models with both variables. RESULTS: We identified 466 incidence cases of COPD. The incidence rate per 100 person-years was 0.81 (95% confidence interval [CI], 0.73-0.89) in males and 0.31 (0.24-0.38) in females, and significantly increased with age in both sexes. The incidence rate for current smokers was significantly higher than that for male non-smokers but not significantly for females. Among males, the IRR for current smokers with Brinkman Index < 400, 400-799, and 800+ was 1.2 (0.8-1.9), 2.7 (1.9-3.8), and 4.6 (3.3-6.5), respectively. CONCLUSION: These results indicated that the COPD risk gradually increased with aging, and that there was a dose-response relationship between smoking and COPD risk.

Effects of smoking and age on chronic obstructive pulmonary disease in Japan.

BACKGROUND: The Global Initiative for Chronic Obstructive Lung Disease guidelines recommended a forced expiratory volume at one second per forced vital capacity as a standard diagnostic criterion of chronic obstructive pulmonary disease (COPD). A few reports on the risk factors of COPD have used the standard diagnostic criteria. In our study, the effects of age and smoking on COPD in Japan under the standard diagnosis criteria were evaluated. METHODS: Subjects were 11,460 participants aged 25-74 years during health check-ups including spirometry at the Toyota Community Medical Center in Japan. Logistic regression analyses with or without COPD as a dependent variable and age as an independent variable were conducted among non-smokers. The ratio of the observed number of COPD cases in former and current smokers to the number expected for non-smokers with the same distribution of age (O/E) was calculated. RESULTS: The proportion of males incurring COPD significantly increased with age, and the O/E for former and current male smokers was significantly higher than one, i.e., O/E (95% confidence interval) for current smokers with a Brinkman Index of <400, 400-799, and 800+ were 3.10 (2.00-4.81), 2.78 (2.05-3.73), and 4.76 (3.65-6.19), respectively. Among females, the O/E for current smokers with a Brinkman Index of <400, and 400-799 were significantly higher than one. CONCLUSION: Age and smoking were shown to constitute strong risk factors for COPD under the standard diagnostic criteria.

[Development of a Japanese version of the Modified Questionnaire on the Pulmonary Functional Status and Dyspnea].

A Japanese version of the Pulmonary Functional Status and Dyspnea Questionnaire (PFSDQ-M) was made through a translation-backtranslation procedure under agreement with the original author, Dr. Lareau, SC. Three components of the Japanese version, dyspnea with activities (DA), fatigue with activities (FA), and change experienced by patients with activities (CA), were tested using 63 chronic respiratory disease (CRD) patients. Cronbach's alpha was the same, 0.93, for DA, FA and CA. Average values for DA, FA, and CA were significantly associated with the MRC and BDI scores in 63 patients. In 43 Chronic Obstructive Pulmonary Disease (COPD) patients, average values for DA, FA, and CA were significantly associated with the % predicted FEV1.0. After 26 patients were randomly selected, the same protocol was repeated with a 10- to 14-day interval to validate the reproducibility of the PFSDQ-M. Correlation coefficients were 0.94, 0.88, and 0.91 for DA, FA, and CA, respectively. Then, 52 patients were randomly selected and the same protocol was repeated with a 6- to 12-month interval to evaluate the sensitivity of PFQD-M. The changes in DA, FA and CA with the 6- to 12-month interval were significantly associated with changes in MRC and TDI. In 37 COPD patients, changes in DA, FA, and CA with the 6- to 12-month interval were significantly associated with the changes in the % predicted FEV1.0. These results show that the Japanese version of PFSDQ-M is valid in its reproducibility and internal consistency, and may also have construct validity and sensitivity for evaluating the functional status and dyspnea of patients with chronic respiratory illness.