Men with idiopathic pulmonary fibrosis (IPF) have poorer lung function and a higher frequency of heart-related diseases (comorbidities) than women with IPF, according to a Swedish study.
The data, which showed no differences between the sexes in terms of quality of life, suggest that additional research is required to clarify the potential need for gender-specific therapeutic interventions among IPF patients.
The study, “Gender differences at presentation of idiopathic pulmonary fibrosis in Sweden,” was published in the journal BMC Pulmonary Medicine.
IPF is more frequent in men than in women, and a previous study showed that men are at a higher risk of death compared with women. However, the mechanisms behind these gender differences are still poorly understood.
In addition, potential gender differences in disease presentation, as well as in comorbidities — the simultaneous presence of two chronic diseases or conditions in a patient — remain unclear.
“Gender differences may have important implications in the diagnosis, treatment and prognosis of IPF and a better understanding of these differences may also give us new clues about [IPF’s underlying mechanisms],” the researchers said.
To learn more, the team of researchers now set out to identify potential gender differences among IPF patients by analyzing clinical data included in the Swedish IPF Registry. This web-based registry, initiated in 2014, covers approximately 60% of respiratory medicine units in Sweden.
The team analyzed data from 348 people with IPF — 250 men and 98 women — with a median age of 72, and ages ranging from 46 to 88. These patients, included in the registry between September 2014 and December 2017, had mild-to-moderate IPF.
The analyzed data included demographics, smoking status, lung function as assessed through several validated tests, exercise capacity — measured using the 6-minute walk test (6MWT) — comorbidities (mostly patient-reported), and quality of life, as measured by the King’s Brief Interstitial Lung Disease Questionnaire (K-BILD) score.
The results showed there was a significantly higher proportion of ex-smokers, and higher exposure to tobacco among men (68%) compared with women (54%).
Among ex-smokers, IPF’s onset occurred approximately 20 years after patients quit smoking. The researchers noted that this finding agreed with previous data from a German registry study.
“This seems to identify a specific risk group [for IPF] which could be a target for screenings for early diagnosis,” the investigators said.
Men with IPF also showed a significantly poorer lung function, compared with women — and this difference was even more pronounced within the ex-smokers group.
Exercise capacity was generally similar between the two genders.
Multiple concurrent diseases were observed in 77% of the male group, and in 80% of the female group. High arterial blood pressure and acid reflux were the most common comorbidities among all patients.
Notably, men had a more than three times greater likelihood of having heart-related diseases — including heart failure and atrial fibrillation — than women. In turn, thyroid-related diseases, asthma, and osteoporosis, a disease that weakens bones, were more common among women with IPF than men with the disease.
Despite differences in disease burden between the two genders, patients showed similar K-BILD scores in terms of quality of life. These scores reflected an overall poor quality of life for both men and women.
The team hypothesized that the similar scores between men and women may be related to the K-BILD test’s insufficient sensitivity in detecting differences between genders. The differences also could be due to the distinct domains — physical in men and emotional in women —mainly affected by IPF.
However, chest symptoms assessed through the K-BILD were more frequent in women than in men within the never-smoker group.
Additional analyses showed that higher values of mean predicted forced vital capacity, a measure of lung function, were associated with better quality of life in men, but not in women.
Overall, the team concluded that “females have a more preserved lung function than male patients at presentation, while the prevalence of cardiovascular diseases such as coronary heart disease is increased in males.”
The researchers noted, however, that larger studies are required to confirm these gender differences, and “to elucidate the potential need for tailored therapeutic interventions and overall care on the basis of gender.” More studies are also needed to better understand the impact of comorbidities on IPF patients’ survival, quality of life, and symptom burden, the team said.