COPD patients increasingly at risk of dying from non-respiratory causes
Patients with chronic obstructive lung disease (COPD) and on oxygen are increasingly at higher risk for death from non-respiratory diseases, finds a new study.
Researchers from Sweden who studied 7,628 adult patients on long-term oxygen therapy (LTOT) for COPD, between between January 1987 and December 2004, found the annual risk of dying from circulatory and digestive diseases rose 2.8 and 7.8 percent respectively.
The authors say the findings are important for physician monitoring of co-existing conditions that can improve survival of COPD patients.
In the study, the patients were followed an average of 1.7 years. During the study period, 5,497 patients died. End-point was discontinuation of oxygen therapy or death.
"In recent decades the demography of patients starting LTOT for COPD has changed markedly," said Magnus P. Ekström, MD, respiratory medicine physician and researcher, Blekinge Hospital, Karlskrona, Sweden. "In Sweden, the mean age of patients starting LTOT increased from approximately 66 to 73 years between 1987 and 2000. There has also been a significant increase in the proportion of women receiving LTOT for COPD; in fact, the majority of patients starting LTOT are now women."
Cause of death for respiratory disease rose 2.7 percent and for lung cancer, the increase was 2.7 percent in the COPD patients. The researchers found a 1.6 percent increased risk of dying, overall.
In oxygen-dependent COPD, mortality has decreased for respiratory disease and increased for non-respiratory causes, such as cardiovascular disease," Dr. Ekström said. "This supports the importance of optimized diagnostics and treatment of coexisting diseases and conditions to improve survival in severe COPD."
Dr. Ekström notes the cause of death for COPD patients may be shifting because of tobacco cessation and advanced age for starting oxygen therapy.
"Tobacco exposure has decreased overall in Sweden, resulting in a delay in the decline of lung function, which means patients are generally older when they require LTOT," he said. "However, although smoking has decreased overall, the rate of decrease has been greater in men than in women. Previous studies have also shown women may be more likely to be adversely affected by smoking, which may also contribute to an increase in the number of women developing COPD and requiring LTOT.
The authors suspect advanced age of patients starting oxygen therapy for COPD places them at risk of dying from non-respiratory causes. Dr. Ekström said. "Physicians who treat COPD with LTOT need to be aware of these shifts and to monitor for other conditions that may influence the risk of death in these patients."
Am. J. Respir. Crit. Care Med., Jan 2011; doi:10.1164/rccm.201010-1704OC
"Trends in Cause-Specific Mortality in Oxygen-Dependent COPD"
Magnus P Ekström, Philippe Wagner, and Kerstin E Ström