Former smokers survive longer

Patients with severe chronic obstructive pulmonary disease (COPD) who stop smoking may be able to improve their rate of survival. A study has shown that patients with severe, early-onset COPD who continued to smoke had a risk of mortality that was almost three times that of patients who stopped.

"Lifetime smoking intensity and current smoking status independently increased mortality in our patients with severe COPD," states Craig R Hersh, Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Boston. "However, patients who continued smoking significantly reduced their survival rate, which confirms the importance of smoking cessation even in patients with the most advanced stages of lung disease."

Hersh utilized data from the Boston Early-Onset COPD Study to determine the survival rates of patients under age 53 during a follow-up period of two months to eight years. Of the 139 patients (72.7% women) studied, 37 died within the study period, with the majority of deaths due to cardiorespiratory illness. Overall survival rates were 85% at three years and 72% at five years. Patients who smoked during the study period had a risk of mortality that was almost three times that of patients who quit. In addition, greater smoking intensity was associated with decreased survival, and the risk of mortality increased by 20% for each 10 pack-years of smoking.

"As age increases, so does the risk of mortality in patients with COPD," Hersh points out. "Yet, the relatively young patients in our study had a high rate of mortality, despite their age."

Although women made up the majority of patients in the study, both groups had similar rates of survival. In addition to age and gender, symptoms of home oxygen use, bronchodilator responsiveness, chronic bronchitis, being underweight, pulmonary rehabilitation, and lung volume reduction surgery were not significant predictors of survival.

"The large number of female patients with severe, early-onset COPD has been an interesting finding of our study that we have not yet been able to explain fully," says Edwin K. Silverman, the principal investigator of the Boston Early-Onset COPD Study. "It is possible that women are more susceptible to the harmful effects of cigarette smoke and that this increased susceptibility has not been appreciated due to the historically higher rates of smoking among men."

COPD is the fourth-leading cause of death in the U.S., with mortality rates significantly increasing among women each year. COPD currently is diagnosed in at least 10,000,000 Americans, and the majority of cases are attributed to long-term cigarette smoking.

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