Do chronic obstructive pulmonary disease (COPD) patients that snore have an increased risk of obstructive sleep apnea?

Co-morbid disease in COPD – more than a coincidence Chronic obstructive pulmonary disease (COPD) is a major cause of disability and death worldwide. Its prevalence and mortality are increasing disproportionately among the elderly, women, persons of lower socioeconomic status, and the populations of developing countries (Anthonisen 1988; Borson et al 1998; Andreassen and Vestbo 2003). There is increasing recognition that COPD is a complex disorder, with many associated co-morbidities. The term " co-morbid " has traditionally been interpreted as " a medical condition existing simultaneously but independently with another condition in a patient. " However, this does not seem to fi t the more recent research on patients with COPD as co-morbid conditions occur more frequently in these patients that would be expected by chance. Such conditions include cardiovascular disease (CVD) Some of these conditions may be worsened by COPD or complicated by COPD. For instance raised airway glucose concentrations in the airways that may occur in diabetes have been shown to precede an increase of respiratory pathogens (Baker et al 2006) and cardiovascular disease (CVD) is a very common cause of death in patients with COPD (Calverley and Scott 2006). The paper by Anecchino and colleagues (2007) in this issue adds to the literature on the prevalence of co-morbidities in patients with COPD reporting on a study of the prevalence of COPD and 3 treated co-morbidities: CVD, depression and osteoporosis in Italy. This is an important study as it utilizes data from a large cohort of approximately 123,000 possible COPD patients. Of note is the high proportion (98%) of these patients who had been prescribed at least one " nonrespiratory " drug. We need however to be cautious in interpreting this data for a number of reasons. Patients in this study were defi ned as having COPD and the co-morbid conditions by drug treatment rather than having a specifi c diagnosis. This means the patients studied may have had other respiratory diseases such as asthma and that patients with untreated CVD, depression and osteoporosis are excluded. Unfortunately, the authors chose to report on just three specifi c co-morbidities, cardiovascular, diabetes and depression. It is hoped that the authors will go on to include other important co-morbidities such as osteoporosis. There appear to be a number of mechanisms by which co-morbid conditions arise in patients with COPD other than by chance. The fi rst of these is sharing of common …