Lack of relationship between functional ability and skin score in patients with systemic sclerosis

To examine the hypothesis that functional ability is related to skin score in patients with systemic sclerosis (SSc).

In 140 patients with SSc attending clinics in the northwestern region of England, functional ability (measured using a recently developed 11 item functional questionnaire) was correlated with skin score (measured using a modified Rodnan technique--17 sites, maximum score 3 for each site).

The median functional score was 6 (range 0-31) and the median skin score 7 (range 0-37). There was no correlation between functional score and total skin score (rS = 0.11, p = 0.19, Spearman). Because most of the questions of the functional score related to upper limb function, separate analyses were undertaken restricting consideration of skin involvement to (1) upper limbs only and (2) digital skin only, versus the overall functional score. Again, no evidence of an association was observed.

Functional ability in this broad group of patients with SSc cannot be predicted from the skin score. Although skin score is useful prognostically, it is not a major determinant of a patient's ability to perform activities of everyday living.