Practical application and validation of the 2018 ATS/ERS/JRS/ALAT and Fleischner Society guidelines for the diagnosis of idiopathic pulmonary fibrosis

Background Accurate diagnosis of idiopathic pulmonary fibrosis (IPF) is essential to inform prognosis and treatment. In 2018, the ATS/ERS/JRS/ALAT and Fleischner Society released new diagnostic guidelines for usual interstitial pneumonitis (UIP)/IPF, adding Probable UIP as a CT category based on prior studies demonstrating this category had relatively high positive predictive value (PPV) for histopathologic UIP/Probable UIP. This study applies the 2018 ATS/ERS/JRS/ALAT and Fleischner Society guidelines to determine test characteristics of CT categories in academic clinical practice. Methods CT and histopathology were evaluated by three thoracic radiologists and two thoracic pathologists. Comparison of consensus categorization by the 2018 ATS and Fleischner Society guidelines by CT and histopathology was performed. Results Of patients with CT UIP, 87% (PPV, 95% CI: 60–98%) had histopathologic UIP with 97% (CI: 90–100%) specificity. Of patients with CT Probable UIP, 38% (PPV, CI: 14–68%) had histopathologic UIP and 46% (PPV, CI: 19–75%) had either histopathologic UIP or Probable UIP, with 88% (CI: 77–95%) specificity. Patients with CT Indeterminate and Alternative Diagnosis had histopathologic UIP in 27% (PPV, CI: 6–61%) and 21% (PPV, CI: 11–33%) of cases with specificities of 90% (CI: 80–96%) and 25% (CI: 16–37%). Interobserver variability (kappa) between radiologists ranged 0.32–0.81. Conclusions CT UIP and Probable UIP have high specificity for histopathologic UIP, and CT UIP has high PPV for histopathologic UIP. PPV of CT Probable UIP was 46% for combined histopathologic UIP/Probable UIP. Our results indicate that additional studies are needed to further assess and refine the guideline criteria to improve classification performance.

COVID-19 Associated Interstitial Lung Disease - An Emerging Entity

Background: COVID-19 disease associated pulmonary sequalae has been increasingly reported after recovery from acute infection. Therefore, we aim to explore the charactersitics of interstitial lung disease in patients with COVID-19.Methods: An observational study was conducted in patients with COVID-19 associated ILD from April 2020 till September 2020. Patients ≥18 years of age with COVID-19 who were diagnosed with ILD based on respiratory symptoms and HRCT chest imaging after the recovery phase of COVID-19 infection were recruited. Data was recorded on a structured proforma, and descriptive analysis was performed using Stata version 12.1.Results: A total of 30 patients with COVID-associated ILD were identified. The mean age of patients was 59.14 (SD 12.60) and 27 (90%) were males. Four HRCT patterns of interstitial lung disease were seen; organizing pneumonia in 10 (33.33%), non-specific interstitial pneumonitis in 17 (56.67%), usual interstitial pneumonitis in 12 (40%) and probable usual interstitial pneumonitis in 14 (46.67%). Diffuse involvement was found in 15 (50%) patients, while peripheral predominance in 15 (50%) and other significant findings were seen in 8 (26.67%) patients. All patients were treated with corticosteroids. The case fatality rate was 16.67%. Amongst the survivors, 8 (32%) recovered completely, 9 (36%) improved, while 8 (32%) patients had static or progressive disease.Conclusions: This is the first study from Southeast Asia that identified COVID-associated interstitial lung disease in patients who had no pre-existing lung disease, highlighting the importance of timely recognition and treatment of an entity that might lead to fatal outcome.