Derivation and validation of a prediction rule for two-year mortality in early diffuse cutaneous systemic Sclerosis

Robyn T. Domsic, Svetlana I. Nihtyanova, Stephen R. Wisniewski, Michael J. Fine, Mary Lucas, Chian K Kwoh, Christopher P. Denton, Thomas A. Medsger

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Abstract

Objective Systemic sclerosis (SSc) is associated with a reduction in life expectancy, but there are no validated prognostic models for determining short-term mortality. The objective of this study was to derive and validate a prediction rule for 2-year mortality in patients with early diffuse cutaneous SSc (dcSSc). Methods We studied a prospectively enrolled cohort of 387 US Caucasian patients with early dcSSc (<2 years from the appearance of the first symptom), randomly divided into a derivation cohort (n = 260) and a validation cohort (n = 127). Predefined baseline predictor variables were analyzed in a stepwise multivariable logistic regression model in order to identify factors independently associated with 2-year all-cause mortality using a cutoff of P < 0.05. We rounded the beta values to the nearest integer and summed the points assigned to each variable in order to stratify patients into low-risk, moderate-risk, and high-risk groups. We then applied this rule to an external validation cohort of 110 Caucasian patients with early dcSSc from a single UK center and compared stratum-specific mortality using chi-square statistics. Results Four independent predictor variables (with assigned integer values) comprised the model: age at first visit (points allotted: -1, 0, or 1), skin thickness progression rate (points allotted: 0 or 1), gastrointestinal tract severity (points allotted: 0, 1, or 2), and anemia (points allotted: 0 or 2). The prediction model performed well, with no significant differences between the derivation cohort and the US or UK validation cohorts in the low-risk and moderate-risk groups. Conclusion We derived a 4-variable prediction rule that can be used to stratify patients with early dcSSc into groups by risk of 2-year mortality, and we validated that prediction rule in US and UK cohorts.

Original languageEnglish (US)
Pages (from-to)1616-1624
Number of pages9
JournalArthritis and Rheumatology
Volume66
Issue number6
DOIs
Publication statusPublished - 2014
Externally publishedYes

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ASJC Scopus subject areas

  • Immunology
  • Immunology and Allergy
  • Rheumatology

Cite this

Domsic, R. T., Nihtyanova, S. I., Wisniewski, S. R., Fine, M. J., Lucas, M., Kwoh, C. K., ... Medsger, T. A. (2014). Derivation and validation of a prediction rule for two-year mortality in early diffuse cutaneous systemic Sclerosis. Arthritis and Rheumatology, 66(6), 1616-1624. https://doi.org/10.1002/art.38381