The influence of smoking on the course of idiopathic pulmonary fibrosis (IPF) is complex, and a recent study did not manage to significantly disentangle the relationship. While smoking appeared to influence the onset of IPF, with current smokers falling ill at a younger age, the study found no impact of smoking history on patient survival when taking other factors into account.
Neither did the number of co-morbid conditions influence how long a patient lived, said researchers from Kuopio University Hospital in Finland.
With this, the study “Effect of smoking and comorbidities on survival in idiopathic pulmonary fibrosis,” published in the journal Respiratory Research, concluded that more research is needed to understand the impact of smoking in the course of IPF.
The research team, which collaborated with colleagues at the University of Eastern Finland, retrospectively examined the medical records of 132 IPF patients — 73.5 percent men and 26.5 percent women.
Among them were 66 ex-smokers, 17 current smokers, and 45 people who had never smoked.
Current smokers were significantly younger when they were diagnosed with IPF. They also died at a younger age than both ex-smokers and non-smokers. They had, however, smoked longer, with more pack-years than ex-smokers.
Non-smokers lived for a median of 55 months after diagnosis, followed by current smokers who lived for 52 months. Ex-smokers survived for a significantly shorter period of time — only a median of 36.0 months. Earlier studies have reported similar findings.
But when the team added age and disease severity scores to the analysis, smoking had no impact on survival. Age at diagnosis and disease severity were better predictors of survival in these patients.
Looking at the presence of other diseases among the patient cohort, cardiovascular diseases were the most common ones, affecting 72.7 percent; followed by coronary artery disease, high blood pressure, diabetes and heart failure.
Researchers discovered that men who currently smoked had significantly more chronic obstructive pulmonary disease (COPD) and lung cancer compared to ex-smokers.
Performing an analysis taking several factors into account, the team noted that age, but not smoking history, was related to the number of comorbid conditions a patient had. Nevertheless, the number of co-morbidities did not impact survival.
Despite the lack of associations between smoking or co-morbidities and survival, researchers argued that the fact that current smokers fell ill at an earlier age indicated that smoking might have an influence on IPF.
More research into this relationship is, however, needed, they said.