More than a quarter of patients with cardiovascular disease (CVD) and a history of smoking also have air flow limitation compatible with chronic obstructive pulmonary disease (COPD), Japanese study data show.
Strikingly, the vast majority (87.7%) of patients found to have such airflow limitation had not previously been diagnosed with COPD, report Katsuya Onishi (Onishi Heart Clinic, Mie) and colleagues.
“This suggests that it is important to look routinely for COPD in CVD patients >40 years old with a history of smoking, as the combination of COPD with CVD is known to be associated with poorer prognosis”, they remark.
The researchers prospectively measured forced expiratory volume in 1 second (FEV1) and in 6 seconds (FEV6) by handheld spirometry in 995 consecutive outpatients (mean age 66.6 years, 95.5% men) with a smoking history who routinely visited one of 17 CVD clinics in Japan. The 269 patients with a FEV1/ FEV6 ratio less than 0.73 were classed as having airflow limitation compatible with COPD.
These patients were, on average, significantly older than patients without airflow limitation (71 vs 65 years), had a significantly lower mean body mass index (23.3 vs 25.1 kg/m2), and were more likely to have chronic bronchitis symptoms (25.3 vs 18.6%) and a higher COPD assessment test score (8.3 vs 6.4).
Although the prevalence of COPD increased with age (up to 39% in those aged 70 years and older) and was more likely to have previously been diagnosed in older patients (13.8% of those aged 70 years and older), cases still occurred in younger patients, with a rate of 5.1% observed in those aged 40 to 49 years, none of whom had been previously diagnosed.
As expected, the percentage of patients with a prior diagnosis of COPD increased with increasing spirometry use, but still only reached 14.0% in centres classed as using spirometry “often” (≥10 times/month), compared with 11.1% in those that seldom used it (<2 times/month).
The researchers also point out that around 20% of the patients they studied had lung function less than 50% of the Global initiative for chronic Obstructive Lung Disease FEV1 predicted values. This shows that even patients with severe to very severe airflow limitation had not previously been diagnosed with COPD, they say.
The study findings are published in the International Journal of Chronic Obstructive Pulmonary Disease.
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