Current Developments in Interstitial Lung Disease

Frequency of Interstitial Lung Disease in Rheumatoid Arthritis Patients: A Hospital-Based Study

Introduction: Among various extra-articular manifestations of rheumatoid arthritis (RA), interstitial lung disease (ILD) is the most frequent and concerning manifestation. The reported frequency of RA-associated ILD (RA-ILD) varies in the literature. The objective of the present study was to determine the frequency of ILD in RA patients at a teaching hospital in Rawalpindi.

Methods: 175 male and female patients between 18-70 years were enrolled in the study from January 21, 2022, till July 24, 2022. Patients diagnosed with RA were screened for the concomitant presence of ILD (increased pulmonary markings on chest X-rays and total lung capacity ≤ 80%, predicted on pulmonary function tests). In addition, the frequency of RA-ILD was noted and compared across various subgroups of patients based on age, gender, and disease duration.

Results: The mean age of the patients was 45.3 ± 11.5 years. The male-to-female ratio was 1:3.1. The mean disease duration was 6.2 ± 3.5 years at the time of presentation. A total of 118 (67.4%) patients were diagnosed with RA-ILD. The frequency of RA-ILD was significantly higher among patients with a prolonged duration of disease, < 5 years vs. ≥ 5 years (59.1% vs. 75.9%; p-value=0.018). Among 118 patients with RA-ILD, usual interstitial pneumonia (UIP) was the most frequent pattern and was noted in 74 (62.7%) patients, followed by nonspecific interstitial pneumonitis (NSIP), which was noted in 44 (37.3%) patients. When compared, there was no statistically significant difference in the frequency of high-resolution CT (HRCT) pattern of RA-ILD across various subgroups of patients based on age (p-value=0.969), gender (p-value=0.934), and duration of disease (p-value=0.881).

Conclusion: In the present study, a substantial proportion of RA patients suffered RA-ILD, which warrants routine screening of these patients for undiagnosed pulmonary involvement so that timely identification and anticipated management may improve the outcome of such cases in future clinical practice.

Trends and seasonal variation of hospitalization and mortality of interstitial lung disease in the United States from 2006 to 2016

Background

In the recent years, the overall trends in hospital admission and mortality of interstitial lung disease (ILD) are unknown. In addition, there was some evidence that interstitial lung disease death rate highest in the winter but this finding was only available in one study. This study will investigate the trend and seasonal variations in hospital admission and mortality rates of ILD from 2006 to 2016.

Method

From the Nationwide Inpatient Sample database, we collected all cases with the International Classification of Diseases (ICD)-9 or ICD-10 codes of ILD excluding identifiable external causes (drug, organic or inorganic dusts) from 2006 to 2016. Hospitalization rates of each year were calculated based on U.S Census population data. Monthly hospitalization and in-hospital mortality rates were analyzed by seasonal and trend decomposition. Subgroups of idiopathic interstitial fibrosis (IPF), acute respiratory failure (ARF), pneumonia were analyzed.

Results

From 2006 to 2016, all-cause hospital admission rate of patients with interstitial lung disease (ILD) and IPF-only subgroup declined but their overall mortality remained unchanged (except IPF subgroup and acute respiratory failure subgroup). Acute respiratory failure related admission account for 23% of all causes and pneumonia 17.6%. Mortality of ILD in general and subgroup of ILD with ARF was highest in winter, up to 8.13% ± 0.60 and 26.3% ± 10.2% respectively. The seasonal variations of hospital admission and mortality of ILD in general was not changed when infectious pneumonia cases were ruled out. All cause admission rates were highest in months from January to April. Subgroup analysis also showed seasonal variations with highest hospitalization rates for all subgroups (IPF, ARF, pneumonia) in the months from December to April (winter to early Spring).

Conclusion

From 2006 to 2016, admission rates of ILD of all causes and IPF subgroup declined but in-hospital mortality of ILD of all causes remained unchanged. Mortality of IPF subgroup and acute respiratory failure subgroup trended down. All-cause hospital admissions and mortality of ILD have a strong seasonal variation. Hospitalization rates for all subgroups (IPF, ARF, pneumonia) were highest in the months from December to April.