Colour changes in the feet: a sign of autonomic symptoms in systemic sclerosis

Patients with autonomic dysfunction, or dysautonomia, often report discolouration of their dependent extremities, which is thought to be from venous pooling or acrocyanosis. A subset of patients with SSc are affected by dysautonomia but may be challenging to identify. We sought to determine whether patients with SSc who report discolouration in their feet have a higher burden of autonomic symptoms, including orthostatic, gastrointestinal (GI), urinary, secretomotor and pupillomotor.

167 patients with SSc completed the Composite Autonomic Symptom Score (COMPASS)-31 survey, which queries whether the patient experiences discolouration of the feet or hands. We compared the COMPASS-31 subdomain scores between SSc patients with and without foot discolouration. Seventy-nine patients with postural orthostatic tachycardia syndrome (POTS) also completed the COMPASS-31 questionnaire for comparison.

We found that extremity discolouration is common in POTS and more often affects the feet, whereas in SSc, the hands are more frequently involved; 62% of SSc patients report colour changes in their feet. These patients are more likely to have other autonomic symptoms, including orthostatic (11.7 ± 10.6 vs 8.6 ± 9.9, P = 0.06), GI (11.3 ± 4.3 vs 8.8 ± 4.3, P = 0.0003), urinary (1.4 ± 1.5 vs 0.8 ± 1.3, P = 0.002) and secretomotor (7.0 ± 3.8 vs 5.9 ± 3.8, P = 0.06) symptoms. These associations persist in a multivariable model after adjusting for potential confounders.

Dependent extremity discolouration is common in dysautonomia. Patients with SSc who report colour changes in their feet are more likely to report other symptoms of autonomic dysfunction.