Update on indices of disease activity in systemic sclerosis

An important barrier in the study of systemic sclerosis (SSc) is the difficulty in measuring disease activity. We reviewed the literature on currently available global measures of disease activity in SSc.

The PubMed database (1950-2006) was searched for the key words "scleroderma" in conjunction with "disease activity" and then "disease severity." All relevant original and review articles in English and French were reviewed. Textbooks in rheumatology and pertinent secondary references were also reviewed.

There are currently 3 tools that are used to measure disease activity globally in SSc. Physician global assessments have been commonly used but have not been formally evaluated. The Valentini Disease Activity Index is a new measure that consists of 10 variables and a resulting score ranging from 0 to 10. It appears easy to use but lacks some face and content validity and responsiveness to change has yet to be demonstrated. The Medsger Disease Severity Scale measures disease severity in 9 organ systems. However, it assesses mostly damage and is difficult to score.

There is currently no gold standard measure of disease activity in SSc. Given the need to measure disease activity in SSc and the limitations of the currently available instruments, efforts are ongoing to develop new ones. This represents a major challenge but one that remains particularly important to undertake.