Chronic Obstructive Pulmonary Disease (COPD) Often Associated With Other Illnesses

Main Category: Respiratory / Asthma
Also Included In: Cardiovascular / Cardiology;  Hypertension
Article Date: 25 Sep 2008 - 3:00 PDT

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This is according to an American study. Its authors recommend screening for diabetes, arterial hypertension and cardiovascular disease in patients with COPD.

The study, to be published in the forthcoming issue of the European Respiratory Journal (ERJ), the scientific publication of the European Respiratory Society, finds that chronic obstructive pulmonary disease (COPD) is often associated with other serious illnesses.

Conversely, a patient with diabetes or arterial hypertension should also be screened for COPD and other respiratory conditions, according to the study's authors.

COPD, which includes chronic bronchitis and emphysema, is increasingly prevalent throughout the world. This serious respiratory disease, caused largely by smoking, could become the third most common cause of death in Western countries by 2020, according to calculations by the World Health Organization (WHO).

In view of this danger, considerable efforts are under way to improve management and prevention of COPD. In particular, researchers are attempting to identify which illnesses are frequently linked with COPD and assess their impact on the way the disease progresses.

Among them are David Mannino (Department of Preventive Medicine and Environmental Health, University of Kentucky, Lexington, USA) and his team, who set out to determine what links COPD to cardiovascular disease, hypertension and diabetes, and to assess to what degree the simultaneous presence of several diseases (comorbidity) could affect hospitalisation and mortality rates.

Over 20,000 patients monitored for five years

For their project, two existing databases were combined, one from the ARIC (Atherosclerosis Risk In Communities) cohort and the other from the Cardiovascular Health Study (CHS). Launched in the late 1980s by the US National Institutes of Health, both studies included thousands of subjects, aged over 65 for the CHS and from 45 to 64 for ARIC.

Mannino's team only studied patients for whom adequate pulmonary function data were available, selecting 15,341 volunteers from the ARIC cohort and 4,955 from the CHS.

The total of 20,296 subjects were classified according to the severity of their COPD, using a scale based on the GOLD (Global Initiative for Chronic Obstructive Lung Disease) classification. This involves five stages, from 0 (respiratory symptoms such as chronic cough and expectoration, but without reduction of respiratory function) to 4 (very severe disease with major anomalies revealed by spirometric testing).

In each group of patients, the authors analysed the presence or absence of diabetes, arterial hypertension, or a cardiovascular disease, including angina pectoris, antecedents of myocardial infarction, heart failure, stroke and transient ischaemic attack (TIA). They also noted the levels of hospitalisation and mortality over the five-year monitoring period of the studies.

Over half of patients have a comorbidity

The results published by the ERJ provide food for thought. A total of 530 patients were in one of the more severe COPD categories (GOLD 3 or 4), with another 2,076 suffering from moderate COPD (GOLD 2) and 2,892 for whom the disease was just beginning (GOLD 1).

A further 4,511 subjects could be considered as potentially at risk (GOLD 0) and 2,868 others were found by functional respiratory testing to be suffering from restrictive syndrome (excessively small lung volume).

Finally, the remaining 7,419 subjects, or approximately one-third of the participants, could be classed as "normal" in terms of respiratory function.

Mannino and his team report in the ERJ article that, having analysed each of the groups for comorbidities, they found over half of the COPD patients to be suffering from an associated condition.

This was particularly striking among patients with one of the severe forms of COPD (GOLD stage 3 or 4), for whom the risk of diabetes was increased by 50%, hypertension by 60% and cardiovascular disease by 140%.

Results are similar for the group of non-COPD patients with restrictive syndrome.

In total, less than half of COPD patients (48.9%) did not have a comorbidity. Over one-third (7,359, or 36.3%) had a single comorbidity, while 2,597 (12.8%) had two. There were even 415 patients (2%) with all three.

What is more, the authors emphasise, the risk of hospitalisation during the five-year study period was significantly higher for those with one or more comorbidities.

The association between COPD and cardiovascular disease has not been completely elucidated.

It could arise from a number of factors, including chronic infection, inflammation or a shared risk factor, such as smoking.

Strangely, though, the association with cardiovascular disease appears to be independent of the severity of the respiratory condition: "the risk of cardiovascular disease is the same in patients with severe COPD and those with only early signs of the condition", Mannino comments.

He believes, therefore, that there would be benefits from systematic screening for cardiovascular disease, hypertension and diabetes in COPD patients, and vice versa.

Title Of The Original Article
"Prevalence and outcomes of diabetes, hypertension, and cardiovascular disease in COPD."
D.M. Mannino, D. Thorn, A. Swensen, F. Holguin
Eur Respir J 2008, doi:10.1183/09031936.00012408
Click here to view abstract online.

The European Respiratory Journal is the peer-reviewed scientific publication of the European Respiratory Society (more than 8,000 specialists in lung diseases and respiratory medicine in Europe, the United States and Australia).

European Respiratory Journal