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

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 (F2,3451 = 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 (F2,3451 = 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.

COPD-related features of the study sample (summary statistics).
Group A: Low risk, low symptom burden. Patients have both a low exacerbation rate (0-1 exacerbation and no hospital admissions) and low symptom burden (CAT score < 10). Group B: Low risk, higher symptom burden. Patients have a low exacerbation rate (0-1 exacerbation and no hospital admissions) but high symptom burden (CAT score ≥10). Group C: High risk, low symptom burden. Patients have a high exacerbation rate (≥2 exacerbations annually or any number leading to hospital admission) but low symptom burden (CAT score < 10). Group D: High risk, higher symptom burden. Patients with both high exacerbation rate (≥2 exacerbations annually or any number leading to hospital admission) as well as high symptom burden (CAT score ≥10).
* 33 patients received no treatment for COPD (0.009% of the study sample) BPH: benign prostatic hyperplasia, CHF: congestive heart failure, COPD: chronic obstructive pulmonary disease, DM: diabetes mellitus, IHD: ischemic heart disease, PVD: peripheral vascular disease ICS: inhaled corticosteroids, LABA: long-acting β adrenoreceptor agonists, LAMA: long-acting muscarinic receptor antagonists, M: methylxanthines, PDE4I: PDE4 inhibitors, SABA: short-acting β adrenoreceptor agonists, SAMA: short-acting muscarinic receptor antagonists Supplementary Figure 3 (Left panel) The overall CASIS score among COPD patients, categorized based on their type of treatment; either no treatment, or treatment strategy including inhaled corticosteroids, or treatment strategy not including inhaled corticosteroids. Notable differences have been specified between the no treatment group with the treatment groups.
(Right panel) Self-perceived, subjective notion of patients on whether sleep quality has been improved after initiating current inhalation COPD treatment (whatever this treatment might be). CASIS100: COPD and Asthma Sleep Impact Scale, linearly transformed to a 0-100 scale, COPD: chronic obstructive pulmonary disease, N: number of subjects, SD: standard deviation * p < 0.05 Multiple regression results for CASIS100, using as independent variables the %predicted FEV1 spirometric data post-bronchodilation (%predFEV1postBD) and the total CAT score, without excluding its sleeplessness component. The multiple regression model statistically significantly predicted sleep quality, F2,3451 = 1718.9, p<0.001. Both independent variables added statistically significantly to the prediction.

Sleep quality has been improved following initiation of the current inhalation COPD treatment (N=3025)
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, LL: lower limit, UL: upper limit, SE B: standard error of the coefficient, β: standardized coefficient, R 2 : coefficient of determination, ΔR 2 : adjusted R 2 * p ≤ 0.001

Supplementary Figure 4
Positive correlations between age and poorness in night sleep, as well as between time-sincediagnosis and poorness in night sleep. Spearman rank correlation coefficient ρ has been used. CASIS100: COPD and Asthma Sleep Impact Scale, linearly transformed to a 0-100 scale  Table 2 Summary statistics of different variables of the COPD patients included in this study (CAT score, age, time-since-diagnosis, severity stage), depending on which treatment category they belong to (no treatment, treatment including inhaled corticosteroids and treatment without corticosteroids). The patients in each therapeutic category vary on average in these parameters, especially in CAT scores. CAT: COPD assessment test, COPD: chronic obstructive pulmonary disease, ICS: inhaled corticosteroids, NT: no treatment, SD: standard deviation, T-ICS: treatment scheme containing ICS, T-other: treatment scheme not containing ICS, TsD: time since diagnosis