Insomnia in older adults with chronic obstructive pulmonary disease (COPD) in Hong Kong: a case-control study

This study aimed to determine the frequency and sociodemographic/clinical correlates of insomnia in Chinese patients aged ≥60 years suffering from chronic obstructive pulmonary disease (COPD). In this case-control study of 142 outpatients with COPD and 218 sex- and age-matched control subjects, COPD patients were recruited from a prospective study sample hospitalized in Hong Kong for acute COPD exacerbation (≥2 major COPD symptoms or >1 major+minor COPD symptoms for ≥2 consecutive days). Controls were recruited from social centres in Hong Kong. Activity of daily living was assessed with the Instrumental Activities of Daily Living Scale, life events were evaluated using the Life Event Scale, depressive symptoms were ascertained with the Geriatric Depression Scale, and quality of life was measured using the Medical Outcomes Study Short Form-12. Early, middle and late insomnia were measured using items 4, 5 and 6 of the Hamilton Rating Scale for Depression. The frequency of ≥1 type of insomnia was 47.2% in patients and 25.7% in controls; frequencies of early, middle and late insomnia in patients were 24.6%, 31.0%, and 26.1%, respectively, compared to 14.7%, 14.7% and 11.9% in controls. Group differences were non-significant after controlling for relevant covariates. However, in multiple logistic regression analysis, more physical illnesses (p = 0.02, OR = 1.3, 95% CI = 1.1-1.7) and more severe depressive symptoms (p = 0.009, OR = 1.1, 95% CI = 1.03-1.3) were independently associated with any type of insomnia in COPD patients, accounting for 21.3% of the variance. A significant proportion of older adult Chinese COPD patients suffer from insomnia that warrants more attention in clinical practice.