Avoiding misclassification of thrombotic primary antiphospholipid syndrome as systemic lupus erythematosus (SLE): What are the best-performing SLE classification criteria?

Flavio Signorelli; Gustavo Guimarães Moreira Balbi; Eloisa Bonfá; Eduardo F Borba; Danieli Castro de Oliveira Andrade

doi:10.1177/09612033211033978

Avoiding misclassification of thrombotic primary antiphospholipid syndrome as systemic lupus erythematosus (SLE): What are the best-performing SLE classification criteria?

Lupus. 2021 Oct;30(11):1732-1738. doi: 10.1177/09612033211033978. Epub 2021 Jul 22.

Authors

Flavio Signorelli^{1

2}, Gustavo Guimarães Moreira Balbi^{1

3}, Eloisa Bonfá¹, Eduardo F Borba¹, Danieli Castro de Oliveira Andrade¹

Affiliations

¹ Rheumatology Division, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil.
² Rheumatology Division, Hospital Universitário Pedro Ernesto, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil.
³ Rheumatology Division, Hospital Universitário, Universidade Federal de Juiz de Fora, Juiz de Fora, Brazil.

PMID: 34292093
DOI: 10.1177/09612033211033978

Abstract

Background: Systemic lupus erythematosus (SLE) and Primary Antiphospholipid Syndrome (PAPS) overlap clinical and immunological features. Therefore, misclassification of PAPS patients as SLE is a concern. The ACR/EULAR 2019 SLE classification has never been studied in PAPS.

Objective: To verify if the ACR/EULAR 2019 SLE classification can correctly classify a PAPS patient as not having SLE and compare its performance with the SLICC 2012 SLE classification. Methods: One-hundred thrombotic PAPS patients who fulfilled the Sidney criteria were consecutively screened and those who attended the inclusion criteria were submitted to ACR/EULAR 2019 and SLICC 2012 classifications.

Results: Sixty-seven PAPS patients were included in this study. The majority was female (89.6%) with median age at study inclusion of 45 years (35-53) and median PAPS disease duration of 13 years (8-19). PAPS correct classification was observed more often with ACR/EULAR 2019 than SLICC 2021 criteria (94.0% vs. 64.2%; p < 0.001). The 4 misclassified patients in ACR/EULAR 2019 were also misclassified in SLICC 2012. The comparison of misclassified patients to those correctly not classified as SLE resulted, for both criteria, in higher frequencies of hematological domain [ACR/EULAR 2019 (100% vs. 28.6%, p = 0.010) and SLICC 2012 (95.8% vs. 11.6%, p < 0.001)]. Further analysis of hematological manifestations revealed that for the ACR/EULAR 2019 leukopenia (100% vs. 22.2%, p = 0.004) and for the SLICC 2012 leukopenia/lymphopenia (91.7% vs. 7%, p < 0.001) were more frequent in misclassified group. Proteinuria (20.8% vs. 0%, p = 0.004) and low complement (45.8% vs. 20.9%, p = 0.033) were also more often observed in the incorrectly SLICC 2012 classified patients.

Conclusion: ACR/EULAR 2019 had high accuracy for distinguishing PAPS from SLE, whereas the SLICC 2012 incorrectly classified more than one third of the PAPS patients as having SLE.

Keywords: ACR/EULAR 2019 criteria and SLICC 2012 criteria; Systemic lupus erythematosus; primary antiphospholipid syndrome.

MeSH terms

Adult
Antiphospholipid Syndrome* / classification
Antiphospholipid Syndrome* / diagnosis
Diagnostic Errors
Female
Health Status Indicators
Humans
Lupus Erythematosus, Systemic* / classification
Lupus Erythematosus, Systemic* / diagnosis
Male
Middle Aged
Thrombosis* / diagnosis