{
  "abstract": "Objectives The revised Sapporo criteria have been central to research classification of antiphospholipid syndrome (APS) but have been criticized for heterogeneity and ambiguities in clinical and laboratory definitions. The 2023 ACR/EULAR criteria introduce a compulsory entry requirement and an additive weighted system that incorporates nonthrombotic features, refined obstetric definitions, microvascular disease, and risk stratification by antiphospholipid antibodies (aPL) profile, achieving higher specificity. Objectives: To characterize demographic, clinical and immunological features of a single-center APS cohort; to determine the proportion of patients fulfilling the revised Sapporo and the 2023 ACR/EULAR classification criteria; to assess agreement between these criteria; to identify reasons for discordance.Methods Cross-sectional study of adults with primary APS diagnosis followed in our Rheumatology clinic (2020–2024). Continuous variables are reported as mean ± SD, categorical as frequencies. Group comparisons used ANOVA/Kruskal–Wallis or chi-square/Fisher’s exact tests. Analyses were performed in Python® 3.13.Results Sixty-three patients were included – 47 fulfilling revised Sapporo criteria, 41 fulfilling ACR/EULAR criteria (of which 1 patient fulfilling only ACR/EULAR criteria), and 15 patients fulfilling neither. The agreement was 87.3% (kappa=0.70). Among patients fulfilling revised Sapporo criteria, 40 (85.1%) also met ACR/EULAR and 7 (14.9%) did not. Patients who met ACR/EULAR had higher venous thromboembolism rates (22% vs 0%). Patients not meeting these criteria showed a trend toward higher prevalence of cardiovascular risk factors, with a significant difference only for diabetes (71.4% vs 17.5%; p=0.008). They also had more early miscarriages (42.9% vs 7.5%; p=0.035). One patient met ACR/EULAR but not Sapporo, with thrombocytopenia, valvular vegetations, and triple-positive high-titer aPL. In the unclassified patients, several manifestations plausibly linked to APS but underrepresented in current classification criteria were observed ( figure 1).Abstract PO:01:017 Table 1–2Abstract PO:01:017 Figure 1Clinical phenotypes in patients not meeting classification criteria (n=15). DUs, digital ulcers; MRI, magnetic resonance imaging; PE, pulmonary embolismConclusions ACR/EULAR preferentially classifies Sapporo-positive patients with macrothrombosis, while early obstetric morbidity often falls below its threshold. Diabetes was more frequent in ACR/EULAR-negative patients, suggesting a non–APS-specific vascular burden attenuating classification. Thrombocytopenia, explicitly included in ACR/EULAR, can contribute when combined with nonthrombotic features and high-weight aPL, as in the ACR/EULAR-only case, which also shows its ability to capture cardiac involvement. The unclassified cohort underscores underweighted APS features in both systems and the need to distinguish research classification from individualized diagnosis.",
  "authors": [
    {
      "affiliations": [
        "Department of Rheumatology, Unidade Local de Saúde Almada-Seixal, Almada, Portugal"
      ],
      "name": "Rodrigo Rei"
    },
    {
      "affiliations": [
        "Department of Rheumatology, Unidade Local de Saúde Almada-Seixal, Almada, Portugal"
      ],
      "name": "Susana Matias"
    },
    {
      "affiliations": [
        "Department of Rheumatology, Unidade Local de Saúde Almada-Seixal, Almada, Portugal"
      ],
      "name": "Tomás Stein Novais"
    },
    {
      "affiliations": [
        "Department of Rheumatology, Unidade Local de Saúde Almada-Seixal, Almada, Portugal"
      ],
      "name": "Catarina Abreu"
    },
    {
      "affiliations": [
        "Department of Rheumatology, Unidade Local de Saúde Almada-Seixal, Almada, Portugal"
      ],
      "name": "Ana Catarina Duarte"
    },
    {
      "affiliations": [
        "Department of Rheumatology, Unidade Local de Saúde Almada-Seixal, Almada, Portugal"
      ],
      "name": "Maria José Santos"
    }
  ],
  "title": "PO:01:017 Applicability and agreement of the 2023 ACR/EULAR and revised sapporo classification criteria in a single-center antiphospholipid syndrome cohort",
  "uid": "d232892a-a026-5169-a287-871000a38af1"
}