{
  "abstract": "Introduction Validated instruments for measuring disease activity (e.g., Valentini and EUSTAR indices) in systemic sclerosis (SSc) are important for clinical care and research. The Scleroderma Clinical Trials Consortium Activity Index (SCTC-AI) was developed in 2024 to have face, content, and construct validity. Although SCTC-AI’s construct and predictive validity were demonstrated in Australian and Canadian SSc cohorts, we sought to further assess construct, discriminant, and predictive validity in a US academic SSc cohort.Material and Methods Patients who completed the Routine Assessment of Patient Index Data 3/RAPID3 (range 0-30, lower scores advantageous) and the Patient-Reported Outcomes Measurement Information System 10–Item General Health Short-Form/PROMIS-10 (range 0-100, comprised of Physical and Mental Health Component scores with higher scores advantageous) at two clinic visits one year apart were identified. Clinical data (within three months of each visit) were used to generate SCTC-AI scores (range 0-140, lower scores advantageous) for each time point. PROMIS-10 Physical Health Component (PHC) score groups were ‘Mild/None’ (greater than 35) and ‘Moderate/Severe’ (less than 35). We assessed construct validity with Kendall’s Tau, discriminant validity using the Wilcoxon rank sum test, and predictive validity using unadjusted linear mixed effects models. Statistical analyses were conducted in RStudio (Vienna, Austria).Results One hundred twenty patients were included ( table 1). SCTC-AI scores negatively correlated with PROMIS-10 Physical Health (τ = -0.17, p = 0.02) and Mental Health (τ = -0.11, p = 0.02). Component scores were positively correlated with RAPID3 scores (τ= 0.04, p = 0.52). The median baseline SCTC-AI scores were six and zero in the ‘Moderate/Severe’ and ‘Mild/None’ PHC groups, respectively (p = 0.007). Lower SCTC-AI scores were associated with higher PROMIS-10 Physical Health Component scores, with an average decrease of 0.37 points for every point increase in PROMIS-10 Physical Health scores ( β= -0.37, p = 0.003).Conclusions Baseline and follow-up SCTC-AI scores significantly correlated with PROMIS-10 Physical and Mental Component scores, supporting construct validity. At baseline, SCTC-AI scores differed significantly across PROMIS-10 physical health groups, supporting discriminant validity. SCTC-AI showed weak correlation with RAPID3 scores, demonstrating limited predictive validity. This suggests PROMIS-10 may be more appropriate than RAPID3 for assessing disease status in systemic sclerosis. Work is ongoing to analyze data in a U.S. academic cohort of 220 additional patients.Abstract P.307 Table 1Demographics and patient characteristics, N=120",
  "authors": [
    {
      "affiliations": [
        "Yale School of Medicine, Department of Internal Medicine, Section of Rheumatology, Allergy & Immunology, New Haven, USA"
      ],
      "name": "Ayush Kalia"
    },
    {
      "affiliations": [
        "Yale School of Medicine, Department of Internal Medicine, Section of Rheumatology, Allergy & Immunology, New Haven, USA"
      ],
      "name": "Sophia Ruser"
    },
    {
      "affiliations": [
        "Yale School of Medicine, Department of Internal Medicine, Section of Rheumatology, Allergy & Immunology, New Haven, USA"
      ],
      "name": "Morgan Emokpae"
    },
    {
      "affiliations": [
        "Yale School of Medicine, Department of Internal Medicine, Section of Rheumatology, Allergy & Immunology, New Haven, USA"
      ],
      "name": "Bindu Koyi"
    },
    {
      "affiliations": [
        "Yale School of Medicine, Department of Internal Medicine, Section of Rheumatology, Allergy & Immunology, New Haven, USA"
      ],
      "name": "Abhijeet Danve"
    },
    {
      "affiliations": [
        "Independent Statistician, Washington D.C., USA"
      ],
      "name": "Michael Zamani"
    },
    {
      "affiliations": [
        "Yale School of Medicine, Department of Internal Medicine, Section of Rheumatology, Allergy & Immunology, New Haven, USA"
      ],
      "name": "Bashar Kadhim"
    },
    {
      "affiliations": [
        "Yale School of Medicine, Department of Internal Medicine, Section of Rheumatology, Allergy & Immunology, New Haven, USA"
      ],
      "name": "Ilayda Gunes"
    },
    {
      "affiliations": [
        "Royal Prince Alfred Hospital Sydney and University of Sydney, Department of Rheumatology, Camperdown, Australia"
      ],
      "name": "Mandana Nikpour"
    },
    {
      "affiliations": [
        "Yale School of Medicine, Department of Internal Medicine, Section of Rheumatology, Allergy & Immunology, New Haven, USA"
      ],
      "name": "Monique Hinchcliff"
    }
  ],
  "title": "P.307 Validation of the SCTC-AI in a U.S. systemic sclerosis cohort",
  "uid": "e193e679-84fc-5d4a-be52-87e1ef246097"
}