Pre-existing interstitial lung disease in patients with coronavirus disease 2019: A meta-analysis

BACKGROUND: The impact of pre-existing interstitial lung disease (ILD) on the severity and mortality of COVID-19 remains largely unknown. The purpose of this meta-analysis was to investigate the prevalence of ILD among patients with COVID-19 and figure out the relationship between ILD and the poor clinical outcomes of COVID-19. METHODS: A systematic literature search was conducted in the PubMed, EMBASE, Web of Science and MedRxiv Database from 1 January 2020 to 26 May 2021. RESULTS: 15 studies with 135,263 COVID-19 patients were included for analysis of ILD prevalence. The pooled prevalence of comorbid ILD in patients with COVID-19 was 1.4% (95% CI, 1.1%-1.8%, I(2) = 91%) with significant between-study heterogeneity. Moreover, the prevalence of ILD in non-survival patients with COVID-19 was 2.728-folds higher than that in corresponding survival patients (RR = 2.728, 95% CI 1.162–6.408, I(2) = 54%, p = 0.021). Additionally, 2–3 studies were included for comparison analysis of clinical outcome between COVID-19 patients with and without ILD. The results showed that the mortality of COVID-19 patients with ILD was remarkably elevated compared with patients without ILD (RR = 2.454, 95% CI 1.111–5.421, I(2) = 87%, p = 0.026). Meanwhile, the pooled RR of ICU admission for ILD vs. non-ILD cases with COVID-19 was 3.064 (95% CI 1.889–4.972, I(2) = 0, p < 0.0001). No significant difference in utilizing rate of mechanical ventilation was observed between COVID-19 patients with and without ILD. CONCLUSIONS: There is great variability in ILD prevalence among patients with COVID-19 across the globe. Pre-existing ILD is associated with higher severity and mortality of COVID-19.