Smoker's pack-years, age and area of emphysema are strong predictors of mortality in COPD

Identifying an individual's the smoking history could help doctors to predict survival time in people with COPD.

A new study, which will be presented today (4 September 2012) at the European Respiratory Society's Annual Congress in Vienna, has identified that the measurement, pack-years, is a strong predictor for mortality in COPD.

Chronic obstructive pulmonary disease (COPD) is a term given to a group of conditions which cause a gradual restriction of airflow which gives people difficulty breathing. The condition is largely caused by smoking, yet clinicians are still unsure what factors of the illness will determine a person's survival time from diagnosis.

Researchers analysed 208 people with COPD, 104 of them died during the study. The average survival time for these people was 10.4 years from inclusion. The researchers measured a number of clinical factors including lung function tests, age and patient history, number of pack-years and the degree of emphysema using a CT scan. They then used a statistical survival model, called the Cox proportional hazard regression model, to analyse the probability that each factor could help predict survival time.

The results showed that the age of the patient and their pack-years they had smoked were statistically significant predictors of mortality. The area of emphysema measured by CT scan also emerged as a strong predictor of mortality.

Lead author, Dr Saher B. Shaker, from Gentofte University Hospital in Denmark, said: "Our results have clinical relevance as we have identified three factors, pack-years, age and area of emphysema, as strong predictors of mortality in COPD. It was also interesting to note that measurements taken from the lung function tests did not reach statistical significance."