Co-morbid disease in COPD – more than a coincidence / Do chronic obstructive pulmonary disease (COPD) patients that snore have an increased risk of obstructive sleep apnea? ||FREE PAPER||

Alan J Crockett¹, David Price²

¹Associate Professor, Director, Primary Care Respiratory Research Unit, Discipline of Public Health and Clinical Practice, The University of Adelaide, South Australia; ²General Practice Airways Group, Professor of Primary Care Respiratory Medicine, Department of General Practice and Primary Care, University of Aberdeen, Scotland, UK

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 fit 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) (Calverley and Scott 2006), depression (Borson et al 1998), diabetes (Schmidt et al 1999), lung cancer (Omori et al 2006), and osteoporosis (Vogelmeier and Bals 2007). 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).

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

Nicholas Hart

Consultant in Respiratory and Critical Care Medicine, Lane Fox Respiratory unit, Guy’s and St Thomas’ NHS Foundation Trust, London, UK

Obstructive sleep apnea (OSA) affects around 4% of middle-aged men (Young et al 1993). With this high prevalence of OSA and the rising worldwide increase in morbidity and mortality in chronic obstructive pulmonary disease (COPD) (WHO 2000), it is not surprising that research attentions have focused on the overlap between these two highly prevalent conditions with the aim of determining their relationship. A number of studies have investigated the association between OSA and COPD. In patients with COPD, studies have shown that as the depth of sleep increases so there is a reduction in minute ventilation with an increase in upper airway resistance (Ballard et al 1995) with up to 20% patients with severe COPD exhibiting co-existent OSA (Brander et al 1992). Although the Sleep Heart Health Study (Sanders et al 2003) found that OSA prevalence was not increased in mild COPD, undiagnosed airways obstruction can be present in ≥10 percent of patients with OSA (Lin and Huang 1992). These observations may simply reflect that the clinical relevance of the overlap between COPD and OSA only become apparent when one or both of these conditions are severe.