Underlying and immediate causes of death in patients with idiopathic pulmonary fibrosis

Miia Kärkkäinen, Hanna Nurmi, Hannu-Pekka Kettunen, Tuomas Selander, Minna Purokivi, Riitta Kaarteenaho

The most common cause of death of patients with idiopathic pulmonary fibrosis (IPF) has been reported to be the lung disease itself and mortality from IPF appears to be increasing. However, the causes of death in patients with IPF taking into account differences between genders and smoking histories as well as disease progression, have not been previously explored. Retrospective data from hospital register and death certificates from national database of IPF patients treated in Kuopio University Hospital (KUH) from 2002 to 2012 were collected. Mortality was also explored from the death registry database via ICD-10 code J84 revealing the numbers of deaths from pulmonary fibrosis in Finland from 1998 to 2015. Out of 117 deaths, 26.5% were females and 73.5% males in KUH. The most common underlying causes of death were IPF 67.5% and ischemic heart diseases 14.8%. More males died for reasons other than IPF (39.5%) compared to females (12.9%) (p = 0.007). Pneumonia as the immediate cause of death was more common in males (27.9%) than in females (3.2%) (p = 0.004) and in ex-smokers (32.7%) compared to non-smokers (9.3%) (p = 0.007). Death register based mortality from pulmonary fibrosis is increasing in Finland. Even though the overall mortality was higher in males with IPF, the disease-specific mortality for IPF was higher in females i.e. in males, comorbidities were more often the underlying causes of death. Pneumonia-triggered acute exacerbations of IPF may be associated with smoking and gender since females and non-smokers were less likely to succumb to pneumonia. We conclude that disease progression at the end of life may vary depending on smoking habits and gender.