Localized scleroderma severity index and global assessments: a pilot study of outcome instruments

Abstract

Objective: To develop a disease outcome instrument measuring localized scleroderma (LS) severity and to determine its reliability.

Methods: Patients with LS were evaluated by 2 rheumatologists. The LS Severity Index (LoSSI) comprises the sum of 4 clinical skin scores measured at 14 cutaneous anatomic sites: extent of surface area (SA) affected, erythema score (ES), skin thickness (ST) score, and new lesion/extension (N/E). Physician and patient global assessments (GA) were recorded on a 100 mm visual analog scale.

Results: Twenty-two patients with LS had 66 visits, during which 91 lesions were assessed. Individual skin scores (SA, ES, ST) and LoSSI showed substantial interrater reliability (kappaw 0.77-0.83; percentage agreement 93.41%-96.70%). Intrarater variability was calculated using 26 anatomic sites and 9 pair-visits. Each skin score demonstrated excellent reliability (kappaw 0.56-0.80, percentage agreement 90.39%-94.23%). Physician GA showed substantial interrater correlation [0.72, 95% confidence interval (CI) 0.57, 0.87]. There was only fair correlation between physician and patient GA (0.27, 95% CI 0.00, 0.64). The standardized response means for LoSSI and physician GA were large (1.86 and 2.55) for those who improved after therapy.

Conclusion: LS clinical trials are impeded by the lack of reliable and reproducible outcome measures. We have developed the LoSSI to correct this deficiency. Our pilot study demonstrates that the LoSSI is reliable and reproducible in measuring LS severity and therapeutic effects and can be easily implemented into the clinical examination of patients with LS. Both LoSSI and physician GA were sensitive to clinical changes in patients with LS. A formal study should be conducted to validate these preliminary findings.