tetano
Editor, Senior Moderator
Clin Biochem
. 2021 Jan 18;S0009-9120(21)00004-7.
doi: 10.1016/j.clinbiochem.2021.01.003. Online ahead of print.
Anti-SARS-CoV-2 IgM improves clinical sensitivity early in disease course
Victoria Higgins[SUP] 1 [/SUP], Anselmo Fabros[SUP] 2 [/SUP], Xiao Yan Wang[SUP] 2 [/SUP], Maria Bhandari[SUP] 3 [/SUP], David J Daghfal[SUP] 3 [/SUP], Vathany Kulasingam[SUP] 4 [/SUP]
Affiliations
Abstract
Introduction: Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is diagnosed by molecular-based detection of SARS-CoV-2 RNA. Serologic testing detects antibodies specific to SARS-CoV-2 and IgM specifically may serve as an adjunct test to PCR early in disease. We evaluated the Abbott anti-SARS-CoV-2 IgM and IgG assays along with DiaSorin anti-SARS-CoV-2 IgG and Roche anti-SARS-CoV-2 Total.
Methods: Specimens from 175 PCR-positive patients and 107 control specimens were analyzed using Abbott IgM and IgG, DiaSorin IgG, and Roche Total (IgA, IgG, IgM) assays. Sensitivity, specificity, cross-reactivity, concordance between assays, trends over time, positive predictive value (PPV), and negative predictive value (NPV) were determined.
Results: Abbott IgM sensitivity was 63.6% at 0 days post-PCR positivity, 76.5% at 1-5d, 76.3% at 6-14d, 85.2% at 15-30d, and 63.6% at >30d. All assays exhibited highest sensitivity 15-30d post-PCR positivity (83.3-85.2%). Combining Abbott IgM and IgG improved sensitivity by 22.7% compared to IgG alone when tested 0d post-PCR positivity. All assays had a specificity of 100% and only Abbott IgG exhibited cross-reactivity (anti-dsDNA). Cohen's kappa varied between 0.86-0.93. Time to seroconversion from PCR positivity was lowest for Abbott IgM and highest for Abbott IgG. NPV was highest for Abbott IgM <14 days post-PCR positivity and Abbott IgG ≥14 days.
Conclusion: The Abbott IgM assay exhibited the earliest response and greatest signal in most patients evaluated for serial sampling and had the highest NPV <14 days post-PCR positivity, suggesting its potential utility as an adjunct test to PCR early in disease course.
Keywords: COVID-19; IgM; Immunoassay; SARS-CoV-2; Serology.
. 2021 Jan 18;S0009-9120(21)00004-7.
doi: 10.1016/j.clinbiochem.2021.01.003. Online ahead of print.
Anti-SARS-CoV-2 IgM improves clinical sensitivity early in disease course
Victoria Higgins[SUP] 1 [/SUP], Anselmo Fabros[SUP] 2 [/SUP], Xiao Yan Wang[SUP] 2 [/SUP], Maria Bhandari[SUP] 3 [/SUP], David J Daghfal[SUP] 3 [/SUP], Vathany Kulasingam[SUP] 4 [/SUP]
Affiliations
- PMID: 33476578
- DOI: 10.1016/j.clinbiochem.2021.01.003
Abstract
Introduction: Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is diagnosed by molecular-based detection of SARS-CoV-2 RNA. Serologic testing detects antibodies specific to SARS-CoV-2 and IgM specifically may serve as an adjunct test to PCR early in disease. We evaluated the Abbott anti-SARS-CoV-2 IgM and IgG assays along with DiaSorin anti-SARS-CoV-2 IgG and Roche anti-SARS-CoV-2 Total.
Methods: Specimens from 175 PCR-positive patients and 107 control specimens were analyzed using Abbott IgM and IgG, DiaSorin IgG, and Roche Total (IgA, IgG, IgM) assays. Sensitivity, specificity, cross-reactivity, concordance between assays, trends over time, positive predictive value (PPV), and negative predictive value (NPV) were determined.
Results: Abbott IgM sensitivity was 63.6% at 0 days post-PCR positivity, 76.5% at 1-5d, 76.3% at 6-14d, 85.2% at 15-30d, and 63.6% at >30d. All assays exhibited highest sensitivity 15-30d post-PCR positivity (83.3-85.2%). Combining Abbott IgM and IgG improved sensitivity by 22.7% compared to IgG alone when tested 0d post-PCR positivity. All assays had a specificity of 100% and only Abbott IgG exhibited cross-reactivity (anti-dsDNA). Cohen's kappa varied between 0.86-0.93. Time to seroconversion from PCR positivity was lowest for Abbott IgM and highest for Abbott IgG. NPV was highest for Abbott IgM <14 days post-PCR positivity and Abbott IgG ≥14 days.
Conclusion: The Abbott IgM assay exhibited the earliest response and greatest signal in most patients evaluated for serial sampling and had the highest NPV <14 days post-PCR positivity, suggesting its potential utility as an adjunct test to PCR early in disease course.
Keywords: COVID-19; IgM; Immunoassay; SARS-CoV-2; Serology.