Self-perceived quality of sleep among COPD patients in Greece: the SLEPICO study

Abstract

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide accompanied by a substantial social and economic burden for the patient and the society. Poor sleep quality among COPD patients is frequently unnoticed and unaddressed by physicians and patients themselves, although it is a major source of further deterioration of these patients' quality of life. The aim of the present study was to record the quality of sleep in COPD patients among the Greek population and correlate these findings with various features of these patients, using the COPD and Asthma Sleep Impact Scale (CASIS). This was a cross-sectional observational study. Forty different variables (demographics, vital sign measurements, COPD-related medical history parameters, comorbidities, CASIS questionnaire results, COPD assessment test, COPD severity based on spirometry measurements, COPD stage based on the ABCD assessment approach, inhaled COPD treatment report) were collected from 3454 nation-wide COPD patients (Greece). The study sample consisted of COPD patients, mainly male (73%) with a median age of 69 years and a median BMI of 27.2. More than half of COPD patients (60.6%) suffered from moderate disease severity and 23.8% from severe disease, while less than half (42.1%) suffered from at least one exacerbation of the disease over the last year prior study enrollment. About 14% reported frequent to very frequent issues affecting their sleep quality, between a fourth and a third of them reported occasional night sleep disturbances, and at least half of them reported no or very infrequent problems in their night sleep. Our study indicates that the COPD assessment test (CAT) and the spirometry-based disease severity can predict the poorness in the quality of sleep (F_2,3451 = 1397.5, p < 0.001, adj. R2 = 0.45) as assessed by CASIS score, and that the latter also correlates with age (ρ = 0.122, p < 0.001) and disease duration (ρ = 0.104, p < 0.001). On the contrary, there appears to be no correlation between sleep quality and number of exacerbations. Finally, untreated patients with COPD suffer from poorer quality of sleep compared to treated subjects, independently of the use of inhaled corticosteroids (F_2,3451 = 21.65, p < 0.001). The results of the SLEPICO study show that increased age, prolonged disease duration, and especially CAT score ≥ 10, and severe COPD stage, might act as important indicators for deterioration in the quality of sleep, with potential consequences in the daily routine of those patients, thus urging potentially for further pharmacological interventions or modifications.

Figure 1

(Upper panel) Summary statistics of the overall score and the score from each of the 7 items of the CASIS questionnaire. (Lower panel) Distribution of the responses of the study participants in each of the 7 items of the CASIS questionnaire. To present all data in a uniform manner (in that the directionality of best-to-worst responses is always left-to-right), the values in the last two items have been reversed. CASIS: COPD and Asthma Sleep Impact Scale, CASIS100: COPD and Asthma Sleep Impact Scale, linearly transformed to a 0–100 scale, COPD: chronic obstructive pulmonary disease.

Figure 2

(Α) Plotting the %predicted FEV1 spirometric data post-bronchodilation (FEV1 Post-BD % pred or %predFEV1postBD) against the CASIS100 scores show a negative linear correlation (ρ = −0.180, p < 0.001). (B)Plotting the total CAT score excluding its sleeplessness component (CAT[excl. sleep] or CATex.sleep) against the CASIS100 scores show a positive linear correlation (ρ = 0.668, p < 0.001). (C) As the disease severity increases, patients tend to have higher CASIS scores, i.e., experience poorer quality of sleep. (D) Patients belonging to groups B and D of the GOLD ABCD classification system have notably poorer quality of sleep compared to those belonging to groups A and C. (E) Multiple regression results for CASIS100, using as independent variables %predFEV1postBD and CATex.sleep. B: unstandardized regression coefficient, CASIS100: COPD and Asthma Sleep Impact Scale, linearly transformed to a 0–100 scale, CAT: COPD assessment test, CI: confidence intervals, COPD: chronic obstructive pulmonary disease, GOLD: Global Initiative for Chronic Obstructive Lung Disease, LL: lower limit, UL: upper limit, SE B: standard error of the coefficient, β: standardized coefficient, R2: coefficient of determination, ΔR2: adjusted R2 *p ≤ 0.001.

Figure 3

Sleep outcome, measured by CASIS, based on the different therapeutic approaches, and adjusted to different ranges of CAT score. As we have established so far (see main text and previous figures), sleep outcomes in COPD patients correlate moderately with their age, TsD and disease severity stage, and strongly with the symptoms of the disease (estimated by CAT). For low CAT scores (0–10), treatment or no treatment does not seem to impact sleep outcomes. Nevertheless, for higher CAT scores (11 +), any treatment seems to notably improve sleep outcomes compared to no treatment. After adjusting for the CAT score, the use of ICS does not seem to impact sleep outcomes. CASIS100: COPD and Asthma Sleep Impact Scale, linearly transformed to a 0–100 scale, CAT: COPD assessment test, COPD: chronic obstructive pulmonary disease, ICS: inhaled corticosteroids, N: number of subjects, NT: no treatment, SD: standard deviation, T-ICS: COPD treatment scheme containing ICS, T-other: COPD treatment scheme not containing ICS.