Lung Transplants, Earlier Death Seen as More Likely in Men with IPF Than Women

Joana Carvalho, PhD avatar

by Joana Carvalho, PhD |

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sex differences and IPF

Men with idiopathic pulmonary fibrosis (IPF) are at higher risk of death and are more likely to require a lung transplant than women, according to a recent study.

Researchers also identified coughing to be an independent predictor of survival in men with IPF.

The study, “Differences in Clinical Characteristics and Outcomes Between Men and Women With Idiopathic Pulmonary Fibrosis,” was published in the journal CHEST.

Statistics indicate that about 70% of IPF cases are diagnosed in male patients. Although the reasons why IPF is more prevalent in men than in women are not clear, some studies propose this could be because men are exposed more often to environmental risk factors like cigarette smoking and air pollutants in the workplace, or to sex-related factors like male hormones.

Some studies also suggest that disease progression may be slower in women, and others report that male IPF patients are at greater risk of death.

“Although a sex difference in terms of risk for disease has been consistently observed, whether this disease is truly sexually dimorphic — that is, whether IPF manifests distinctly in each sex — has not been described,” the investigators wrote.

Researchers at the University of Colorado and colleagues analyzed data from patients with interstitial lung diseases (ILDs) stored at registries from two academic tertiary care centers — the University of California San Francisco (2001-2017) and the Mayo Clinic (1993-2017).

Their study included data from 1,263 patients diagnosed with IPF and for whom follow-up data was available. Its main goal was to assess if patient’s sex could be associated with different outcomes, particularly regarding mortality and the need for a lung transplant.

Researchers assessed the contribution of several factors that could be related to these outcomes, including lung function parameters, body mass index (BMI), smoking history, presence of cough or phlegm, and the need for oxygen therapy.

About 71% of the study’s population were male. The median survival of this overall IPF population was 3.1 years.

Results showed that men had a 1.4 times higher risk of mortality or a lung transplant compared to women, after adjusting data for age and lung function.

Survival analyses also indicated that women tended to live longer than men — a median survival of 3.9 years for women versus 2.8 years for men.

The presence of cough, phlegm, and the need for oxygen therapy among the entire group were all associated with a greater risk of death or a transplant, even after adjusting for sex, age, and lung function. In contrast, BMI and smoking history were not seen to independently affect survival.

Analyses also found that older age, poorer lung function (lower values of diffusion capacity for carbon monoxide percent predicted, or DLCO%), and the presence of cough or phlegm were associated with a higher risk of death or transplant in men, but not in women. But among all these factors, only cough was found to differ significantly between the two sexes.

“Our data validate the observation of a male disadvantage in survival within a large cohort of IPF patients, and indicate that cough may be a sex-specific predictor of survival,” the researchers wrote.

“Our findings have potential implications on the development of prognostic algorithms for IPF and our understanding of symptoms in men and women with IPF. Whether true sexual dimorphism [sex differences] exists in IPF, and its impact on pathophysiologic [disease mechanisms] and disease manifestations that may be sex-specific, requires ongoing investigation,” they added.