Can Perinephric Fat Stranding be used as a Predictor of Renal Dysfunction in COVID-19 Patients? A Retrospective Study

Abstract

Introduction: High Resolution Computed Tomography (HRCT) of the chest is often performed in patients with Coronavirus Disease-2019 (COVID-19) to assess the severity of lung involvement. Multiorgan dysfunction is a well-known complication of COVID-19 infection. Bilateral Perinephric Fat Stranding (PFS) is often observed in cases of COVID-19 infection while reporting the chest Computed Tomography (CT) scans, which might represent associated acute kidney injury. It is still not known whether a correlation exists between the severity of COVID-19 infection and presence of PFS or renal dysfunction. Aim: To determine the association between PFS, Computed Tomography Severity Index (CTSI) and serum creatinine levels in patients with COVID-19 infection. Materials and Methods: This retrospective cohort study was conducted in Department of Radiology, Nizam’s Institute of Medical Sciences, Hyderabad, Telangana, India, from April 2021 to June 2021. A total of 90 COVID-19 positive patients of age group 21-80 years of either gender, who underwent HRCT of chest were included in the study. The chest scans were retrospectively reviewed for severity of lung involvement using a CTSI. The data collected was analysed from July 2021 to September 2021. The cases were divided equally into two groups A (n=45) and B (n=45). Group A included cases showing PFS on CT and group B included cases with no evidence of PFS. Serum creatinine levels (obtained within 24 hours of the scan) of all patients were noted and analysed to determine any possible association between the PFS, CTSI and serum creatinine levels. Analysis was done using Mann-Whitney U test, for continuous variables and Chi-square test was used for categorical data. Results: Mean age of cases in group A was 56.16±12.31 years and in group B was 49.91±16.67 years. The mean age of patients (p-value=0.047) and the male to female ratio (p-value <0.001) was significantly higher in group A than in group B. Statistically significant association was found between PFS and serum creatinine (W=1375.500, p-value=0.003). PFS as an indicator of renal dysfunction had a sensitivity of 73.3%, specificity of 54.7%, Positive Predictive Value (PPV) of 24.4%, Negative Predictive Value (NPV) of 91.1% and a diagnostic accuracy of 57.8% with an odds ratio of 3.32. Conclusion: Presence of PFS at imaging can serve as a useful screening tool for detecting underlying renal dysfunction in patients with COVID-19 infection.

Keywords

• acute kidney injury
• coronavirus disease-2019
• computed tomography severity index
• perirenal