Sex-specific epidemiological and clinical differences in spontaneous pneumothorax: A cross-sectional cohort study in Japan.

BACKGROUND

Pneumothorax is less common in females than in males, presenting with distinct features, including catamenial pneumothorax (CP) and lymphangioleiomyomatosis (LAM). However, its clinical characteristics in female patients remain poorly understood. We elucidated the clinical characteristics of pneumothorax in female patients and compared them with those of male patients.

METHODS

This nationwide observational study of 1747 patients with spontaneous pneumothorax was conducted in Japan using a large inpatient database. We characterized spontaneous pneumothorax in female patients and examined sex-specific differences in age distribution and subtype prevalence.

RESULTS

A distinctive trimodal age distribution was observed among females, with the second peak predominantly corresponding to CP and LAM in females of reproductive age. Age was associated with an increased likelihood of secondary spontaneous pneumothorax compared with primary spontaneous pneumothorax, beginning at >35 years in females compared with 60 years in males. Male patients exhibited a bimodal distribution, highlighting age- and sex-specific onset patterns. When CP and LAM cases were excluded, there was no substantial difference in spontaneous pneumothorax occurrence between sexes.

CONCLUSIONS

We highlight the importance of sex-specific evaluation of spontaneous pneumothorax. The trimodal distribution in female patients suggests different underlying mechanisms across age groups. Improved recognition of female-specific subtypes such as CP and LAM, along with multidisciplinary approaches, may lead to more accurate diagnoses and optimized management strategies.