Clinical characteristics and all-cause mortality in female patients with idiopathic pulmonary fibrosis in Chinese population.

Background: Idiopathic pulmonary fibrosis (IPF) exhibits notable sex-based disparities and male patients with IPF are significantly more numerous than female patients. Therefore, the female patients are often overlooked and under-investigated. This study aimed to evaluate the clinical characteristics and all-cause mortality in female patients with IPF in Chinese population.

Methods: This retrospective cohort study included IPF patients registered at Xiangya Hospital of Central South University and the First Affiliated People's Hospital of Shaoyang University from January 2015 to May 2024. The data on age, sex, body mass index, smoking (pack-years), forced expiratory volume in one second to forced vital capacity, diffusing capacity of the lung for carbon monoxide percentage of predicted (DL_CO %pred), diffusing capacity divided by the alveolar volume (DL_CO/VA), laboratory analysis, comorbidities, and antifibrotic therapy were collected. The patients were followed-up to collect the data on all-cause mortality.

Results: A total of 583 patients were enrolled and 116 (19.9%) of them were female. Female patients had higher levels of forced expiratory volume in one second to forced vital capacity, DL_CO %pred, DL_CO/VA, arterial oxygen partial pressure (Pao₂), and total cholesterol, while a lower smoking (pack-years), haemoglobin, blood urea, uric acid, myoglobin, and creatine kinase. The proportion of lung cancer and antifibrotic therapy were lower in female patients (P < 0.05). Logistic regression analysis showed that haemoglobin (odds ratio (OR) = 0.813; 95% confidence interval (CI) = 0.706-0.937) and blood urea (OR = 0.158; 95% CI = 0.030-0.849) as negatively associated with female, while total cholesterol (OR = 14.699; 95% CI = 1.892-114.190) and DL_CO %pred (OR = 1.112; 95% CI = 1.005-1.229) were positively associated (P < 0.05). Over a median follow-up period of 31.0 (12.0-64.0) months, a total of 489 patients with IPF were analysed the all-cause mortality and 101 (20.7%) of them were female. Cox regression analysis revealed that female patients had significantly lower all-cause mortality compared to males (hazard ratio = 0.168; 95% CI = 0.031-0.920, P < 0.05).

Conclusions: Significant differences in clinical characteristics and prognosis were observed between male and female IPF patients in Chinese population. Specifically, female patients exhibited better pulmonary function, higher Pao₂, and lower all-cause mortality than male patients. Therefore, gender differences should be systematically evaluated in the diagnostic and therapeutic approach to IPF, and targeted strategies should be developed to optimise treatment outcomes in female patients.