Cystatin C is a marker for acute kidney injury, but not for mortality among COVID-19 patients in Mexico

BACKGROUND: Patients infected with SARS-CoV-2 can develop acute kidney injury (AKI), associated with adverse clinical outcomes. In Mexico, an AKI incidence of 60.7% was reported in patients with COVID-19. Serum cystatin C is a well-known marker for AKI. It has been postulated as a marker for mortality in Chinese patients with COVID-19. Information regarding levels of cystatin C in COVID-19-infected patients is nonexistent among Mexican or Latin American populations. AIM: This work aimed to assess the level of cystatin C as an indicator of AKI and mortality among COVID-19 patients from Mexico. METHODS: A cross-sectional study among 38 adults was performed in the Regional High Specialty Hospital of the Yucatan Peninsula in Merida, Yucatan, Mexico. Baseline characteristics and clinical and biomechanical parameters were collected, and serum levels of cystatin C were measured by ELISA. RESULTS: A total of 71% (27 patients) with COVID-19 developed AKI; 78% were men, and 22% were women. In addition, 60% of individuals (16 men; 7 women) died due to COVID-19 complications. Serum levels of cystatin C were higher in those individuals who developed AKI (p = 0.001). A logistic regression model indicated that individuals with serum levels of cystatin C above 0.84 ng/mL had a 23-fold increased risk of developing AKI (OR, 23.7, 95% CI, 2.59-217.00, p = 0.005). However, increased cystatin C was not independently associated with mortality in the Mexican population (HR, 1.01, 95% CI, 0.66-1.56, p = 0.959). CONCLUSION: The results suggest that serum levels of cystatin C indicate AKI in COVID-19 patients. Although we recommend caution when using serum cystatin C levels as an indicator of mortality among the Mexican population, it is essential to note that cystatin C elevates earlier than creatinine, which is an advantage for timely clinical interventions.