Epidemiology of Interstitial Lung Disease in the Royal Hospital

Introduction: Interstitial lung disease (ILD) is a group of heterogenous disorders that induces inflammation and fibrosis of the lung parenchyma. It is associated with significant morbidity and mortality. The diagnosis is made by histopathology or radiology. There is limited study on the epidemiology of ILD especially in Oman.

Method: This is a clinical observational cross-sectional study conducted at the Royal Hospital. The study included all patients seen in the Medical Out-Patients clinics during the period January 2016 to December who were diagnosed to have interstitial lung disease based on radiological or histopathological findings. We included patients from the age of 13 years and above. We excluded patients without HRCT or biopsy findings. The data was analyzed using the EPI DATA program.

Results: Out of 239 patients included in the study with a mean age of 63.2 years, and 141 were female. Dyspnea and cough were the most predominant symptoms. Arthralgia was more prominent in females and smoking was more prevalent in males. There was no difference between males and females in the lung function test, however, males walked more distance on 6-minute walk test. Also, more males developed pulmonary hypertension and reduced ejection fraction compared to females. The high-resolution computed tomography (HRCT) findings of reticulation, ground glass opacities, and honeycombing were more significant in females. There was no difference between males and females in the treatment, but prednisolone and azathioprine were more used in females. The overall mortality over a mean of 6 years of follow-up was 14.6% among the interstitial lung disease patients.

Conclusion: ILD was more common in females than males. More males developed complications of ILD including pulmonary hypertension and reduced ejection fraction, however no difference in mortality between the two genders. Further prospective studies to examine the effect of management upon the morbidity and mortality of people with ILD are required to further delineate the prognosis of such patients.