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Serum Amyloid A is a Biomarker of Severe Coronavirus Disease and Prognosis

Our take —

In a small cohort of Chinese inpatients infected with SARS-CoV-2 who had extended in-hospital stays, increasing serum amyloid A and decreasing lymphocyte counts were associated with disease progression. Further study is needed to understand if either of these biomarkers is of clinical use or performs better than previously proposed prognostic markers.

Study design

Retrospective Cohort

Study population and setting

This study was comprised of 132 patients with laboratory-confirmed SARS-CoV-2 infection who were hospitalized for at least 14 days in Wuhan, China between January 18, 2020 and February 26, 2020. Patients underwent a minimum of two batteries of laboratory tests while admitted and three assessments of clinical severity.

Summary of Main Findings

At admission, higher serum amyloid A (SAA) and C-reactive protein, and lower lymphocyte count were associated with disease severity and worse radiographic findings. Levels of SAA, lymphocyte count, and the ratio between the two at admission were good predictors of clinical progression at 3-5 days post admission. Elevation in SAA and decline in lymphocyte count were predictors of worsening clinical status.

Study Strengths

Serial measurement of candidate biomarkers.

Limitations

The sample size was small and the study was conducted in a single-center, potentially limiting generalizeability. Given the requirement of extended hospital stay, this study does not provide information on the risk factors or prognostic indicators for rapid clinical decline. Further, because critically ill patients who died within 14 days were excluded from this study, those who remain may represent a unique population. Given that the authors sought to evaluate inflammatory biomarkers, it is puzzling as to why interleukins and TNF-? were not included. In particular, IL-6 has previously been suggested to be a good candidate marker of COVID-19’s course.

Value added

This study expands the list of candidate biomarkers for COVID-19 risk stratification.