Insomnia symptoms, objectively measured sleep, and disease severity in chronic obstructive pulmonary disease outpatients.
BACKGROUND
Sleep disturbances are known to have a negative impact on a range of clinical outcomes in chronic obstructive pulmonary disease (COPD). We examined the associations of insomnia symptoms and objectively measured sleep parameters to a composite score for body mass index, airflow obstruction, dyspnea, and exercise capacity (BODE) index (a multidimensional index of COPD severity), arterial blood gases, nocturnal respiratory disturbances, periodic limb movements (PLM), psychologic distress, pain, age, and sex.


METHODS
The sample comprised 73 COPD outpatients (mean age, 63.6years; standard deviation {SD}, 7.5; range 47-85years; 41.1% women). Insomnia symptoms were measured with the Bergen Insomnia Scale (BIS) and sleep efficiency (SE), slow-wave sleep (SWS), and total sleep time (TST) were assessed with clinical polysomnography (PSG).


RESULTS
BODE index was positively associated with composite BIS score (P=.040). Patients with more severe COPD presented more complaints of nonrestorative sleep compared to patients with less severe COPD (P=.010). In multivariate analysis, the composite BIS score was independently associated with PLM (P<.001), nocturnal respiratory disturbances (P=.001), pain (P=.031), and psychologic distress (P=.044) but not with the BODE index. Objectively measured sleep variables were not associated with any of the health-related variables.


CONCLUSIONS
Insomnia symptoms in COPD patients result from a wide range of health-related factors. More severe COPD may be associated with a subjective experience of nonrestorative sleep but not with objectively measured sleep variables.
Department of Clinical Psychology, University of Bergen, Christies Gate 12, 5015 Bergen, Norway; NKS Olaviken, Hospital for Old Age Psychiatry, Askvegen 150, 5306 Erdal, Norway. Electronic address: minna.hynninen@psykp.uib.no.
Minna J
MJ
Hynninen
Ståle
S
Pallesen
Jon
J
Hardie
Tomas M L
TM
Eagan
Bjørn
B
Bjorvatn
Per
P
Bakke
Inger Hilde
IH
Nordhus
D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010045:Outpatients; D017286:Polysomnography; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology*; D012720:Severity of Illness Index; D012890:Sleep / Q000502:physiology*; D007319:Sleep Initiation and Maintenance Disorders / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology*; D011795:Surveys and Questionnaires
BODE-index; COPD; Disease severity; Insomnia; Polysomnography; Sleep