Chest Radiograph Scoring Alone or Combined with Other Risk Scores for Predicting Outcomes in COVID-19

Au-Yong, Iain; Higashi, Yutaro; Giannotti, Elisabetta; Fogarty, Andrew; Morling, Joanne R.; Grainge, Matthew; Race, Andrea; Juurlink, Irene; Simmonds, Mark; Briggs, Steve; Cruikshank, Simon; Hammond-Pears, Susan; West, Joe; Crooks, Colin J.; Card, Timothy

BACKGROUND: Radiographic severity may predict patient deterioration and outcomes from COVID-19 pneumonia. PURPOSE: To assess the reliability and reproducibility of three chest radiograph reporting systems (RALE, Brixia, and percentage opacification) in proven SARS-CoV-2 and examine the ability of these scores to predict adverse outcomes both alone and in conjunction with two clinical scoring systems: NEWS2 and ISARIC-4C mortality. MATERIALS AND METHODS: This retrospective cohort study used routinely collected clinical data of PCR-positive SARS-CoV-2 patients admitted to a single UK center from February 2020 until July 2020. Initial chest radiographs were scored for RALE, Brixia, and percentage opacification by one of three radiologists. Intra- and inter-rater agreement was assessed with Intraclass correlation coefficients. The rate of ICU admission or death until 60 days after scored chest radiograph was estimated. NEWS2 and ISARIC-4C mortality, on hospital admission were calculated. Daily risk of admission to ICU or death was modelled with Cox proportional hazards models, incorporating the chest radiograph scores adjusted for NEWS2 or ISARIC-4C mortality. RESULTS: Admission chest radiographs of 50 patients (mean age, 74 years +/-16 [sd], 28 men) were scored by all 3 radiologists, with good inter-rater reliability for all scores (ICCs (95% CIs) of for RALE 0.87 (0.80, 0.92), BRIXIA 0.86 (0.76, 0.92), and percentage opacification 0.72 (0.48, 0.85)). Of 751 patients with chest radiograph, those with >75% opacification had a median time to ICU admission or death of just 1-2 days. Among 628 patients with data (median age 76 years (IQR 61 – 84), and 344 were men), 50-75% opacification increased risk of ICU admission or death by twofold (1.6 - 2.8), and over 75% opacification by 4 fold (3.4 – 4.7), compared to a 0-25% opacification when adjusted for NEWS2 score. CONCLUSION: BRIXIA, RALE, and percent opacification scores all reliably predicted adverse outcomes in SARS-CoV-2. See also the editorial by Little.