Co-morbidity in mild-to-moderate COPD: comparison to normal and restrictive lung function

A relationship between local and systemic inflammation and different co-morbidities, such as cardiovascular, has been discussed in relation to disease process and prognosis in COPD.

To evaluate if conditions as cardiovascular diseases, diabetes, chronic rhinitis and gastroesophageal reflux are overrepresented in COPD.

All subjects with COPD according to GOLD, FEV(1)/FVC<0.70, were identified (n = 993) from the clinical follow-up in 2002-04 of the OLIN (Obstructive Lung Disease in Northern Sweden) studies' cohorts together with 993 gender- and age-matched reference subjects without COPD (non-COPD, further divided into normal and restrictive lung function). Interview data on co-morbidity and symptoms were used.

Cardiovascular co-morbidity, taken together heart disease, hypertension, stroke and intermittent claudication, was the most common and higher in COPD compared to in normal lung function (Nlf) 50.1% vs 41.0% (p<0.001). The prevalence of chronic rhinitis and gastroesophageal reflux (GERD) was higher in COPD compared to in Nlf (43.1% vs 32.3%, p<0.001 and 16.7% vs 12.0%, p = 0.011). In restrictive lung function the prevalence of chronic rhinitis, cardiovascular disease, hyperlipemia and diabetes was higher compared to in Nlf (41.0% vs 32.3%, p = 0.017, 59.0% vs 41.0%, p<0.001, 29.2% vs.12.9%, p = 0.033, 20.9% vs 8.6%, p <0.001). In COPD and heart disease, 62.5% had chronic rhinitis and/or GERD, while in Nlf the corresponding proportion was 42.5%.

Co-morbid conditions such as cardiovascular disease, chronic rhinitis and gastroesophageal reflux were common in COPD. The overlap between heart disease, chronic rhinitis and GERD was large in COPD. Restrictive lung function did also identify a population with increased disease burden.