Heavier smoking significantly increased mortality in adults with progressive fibrosing interstitial lung disease (PF-ILD), based on data from 377 individuals.
The negative impact of smoking on pulmonary diseases is well documented, but the specific impact on patients with PF-ILD has not been well studied,, of St. Antonious Hospital, Nieuwegein, the Netherlands, and colleagues wrote in .
“Patients with PF-ILD or IPF [idiopathic pulmonary fibrosis] are prone to early mortality, indicating a need for prognostic [bio]marker studies for precision medicine,” they said.
The researchers identified adults older than 18 years with PF-ILD who were diagnosed at a single center. All study participants had at least 10% fibrosis, and showed either a decline of at least 10% in forced vital capacity, a 5.0%-9.9% relative FVC decline plus progressive respiratory symptoms and/or an increase in extent of fibrosis on subsequent high-resolution (HRCT progression), or progressive respiratory symptoms and HRCT progression over 24 months after ILD diagnosis.
Pack-years of smoking was a prognostic variable; the researchers also compared median transplant-free survival in heavy smokers and mild to moderate smokers. They also investigated the association between smoking quantity and emphysema in the study population.
Overall, the increased risk for mortality was 11%, 22%, and 44% in patients with 10, 20, and 40 pack-years of smoking, respectively.
Both the unadjusted and adjusted hazard ratio for pack-years were significant (1.014, P < .001 and 1.011, P = .022, respectively).
The median transplant-free survival of ever-smokers versus never-smokers with PF-ILD was 3.3 years versus 4.8 years; median transplant-free survival was 3.0 years for heavy smokers and 3.8 years for mild to moderate smokers. Similarly, median survival was 4.2 years in never-smokers versus 3.0 years in former smokers.
Emphysema was significantly more comment in heavy smokers, compared with never smokers and mild to moderate smokers (P < .001 for both).
“We observed a gradual decrease in survival starting from never to mild-moderate and subsequent heavy smokers supporting our finding that [pack-years] is an independent predictor for mortality in PF-ILD,” the researchers wrote. “This is an important message that clinicians could convey to their ILD patients, but also to patients at-risk for ILD.”
The study findings were limited by several factors, mainly the retrospective design, incomplete data for some patients, and lack of data on comorbidities, the researchers noted. However, the results strengthen the evidence for the detrimental effect of heavy smoking in PF-ILD, they said. Consequently, “efforts to reduce pack-years in those with, and at risk for, PF-ILD may translate into a survival benefit and should have high priority in clinical practice.”
The study was supported by grants from ZonMw TopZorg Care and TZO. The researchers had no financial conflicts to disclose.