Measuring disease activity and damage in discoid lupus erythematosus.

BACKGROUND

Discoid lupus erythematosus (DLE) is a disfiguring inflammatory skin disease. There is no specific tool for measuring disease severity.

OBJECTIVES

To determine the features needed in a score measuring activity and damage in DLE and to investigate the score's reliability and its correlation with the physician's global assessment of disease severity and the patient-reported Dermatology Quality of Life Index (DLQI).

METHODS

The content of the score was determined following a peer review, pilot work in patients and a preliminary inter-rater reliability study. The Score of Activity and Damage in DLE (SADDLE) measures severity of activity (erythema, scale, induration) and damage (scarring/atrophy and dyspigmentation) attributable to DLE. Summed scores range between 0 and 195. Inter- and intrarater reliability of the score was tested using six assessors and nine patients with DLE. Intraclass correlation coefficients (ICCs) > 0.7 were considered evidence of good inter- and intrarater agreement.

RESULTS

The mean +/- SD SADDLE score of nine patients in the inter-rater reliability study was 47 +/- 22 (range 14-102). There was good inter-rater agreement for the total score [ICC 0.82; 95% confidence interval (CI) 0.61-0.95] and for the activity and damage scales, the individual physical signs and the total scores at individual body sites. The total score demonstrated excellent intrarater reliability (ICC 0.98; 95% CI 0.86-1.00). Although there was poor inter-rater agreement for global assessments (ICC 0.28; 95% CI 0.06-0.66), a good correlation was demonstrated between total scores and global assessments (r = 0.7). A weaker positive correlation was observed between disease activity scores and DLQI (r = 0.4).

CONCLUSIONS

The SADDLE measures activity and damage in patients with DLE. It demonstrates good inter- and excellent intrarater agreement, over and above that for global assessment. It correlates well with global assessment scores. Further studies are required to investigate SADDLE's responsiveness to change with therapy.