Predicting Skin Score Changes in Early Diffuse Systemic Sclerosis

Researchers developed 2 predictive models for progressive skin thickening in patients with early diffuse cutaneous systemic sclerosis (SSc) to use in clinical practice and to improve recruitment in clinical trials, using results from The European Scleroderma Observational Study (ClinicalTrials.gov identifier: NCT02339441) published in the Annals of the Rheumatic Diseases.

The investigators sought to identify patients with early diffuse cutaneous SSc who had progressive skin thickness and derive prediction models for disease progression over 12 months. The mRSS was recorded every 3 months in a total of 326 patients. Researchers used logistic models to predict progression that were compared based on the area under curve (AUC), accuracy, and positive predictive value (PPV).

Of the 326 patients, 22.5% were considered “progressors,” defined as participants who experience a 5-unit and 25% increase in mRSS score over 12±3 months, while 77.5% did not progress. The researchers noted that 33 patients did not have their status examined because of insufficient data. Participants who were categorized as “progressors” had significantly shorter disease duration (median 8.1 months vs 12.6 months; P =.001) and significantly lower mRSS (median 19 units vs 21 units; P =.030) compared with nonprogressors. Moreover, skin scores were highest and peaked earliest in the anti-RNA polymerase III (Pol3+) subgroup of patients (n=50).

The results showed that in the first predictive model, which included mRSS, duration of skin thickening, and the interaction between the two, the accuracy was 60.9%, the AUC was 0.666, and the PPV was 33.8%. When a variable for Pol3+ was added to the second predictive model, the model achieved an accuracy of 71%, an AUC of 0.711, and a PPV of 41%.

The investigators concluded that in patients with early diffuse cutaneous SSc, individuals with shorter disease duration and a lower mRSS are most likely to be “progressors.” Utilization of the predictive models developed in this study should help the recruitment process in future clinical trials of diffuse cutaneous SSc.

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Reference

Herrick AL, Peytrignet S, Lunt M, et al. Patterns and predictors of skin score change in early diffuse systemic sclerosis from the European Scleroderma Observational Study. Ann Rheum Dis. 2018;77(4):563-570.