Impact of foot functionality in patients with systemic sclerosis: Cross-sectional study

Background: Progressive systemic sclerosis or systemic scleroderma (SS) is a chronic and rare autoimmune disease that mainly affects the skin and various internal organs. Raynaud's phenomenon and digital ulcers are some of the symptoms that affect the foot, causing a decrease in the quality of life of patients. The objective of this study is to determine the functionality of the feet in patients with SS and determine the impact on their daily lives. Methods: A sample of 165 patients (154 women, 11 men) diagnosed with SS with a mean age of 46.29 +/- 11.36 years and a mean body mass index (BMI) of 24.90 +/- 5.77 was recruited. Each participant completed the Foot Function Index (FFI) questionnaire and the Systemic Sclerosis Questionnaire (SySQ). A multivariate analysis was performed to determine which factors were related to a higher score in both questionnaires. Results: 32.1% of the participants (n = 53) had claw toe deformities, 79.4% (n = 131) Raynaud's disease and 20% (n = 33) a history of foot ulcers. 51.5% of the participants (n = 85) presented symptoms in their nails, the most frequent sign being thickening, hardening and yellow coloration. The final score of the FFI questionnaire was 3.51 +/- 2.41 (0-9.9), the pain subscale being the highest, with a score of 5.06 +/- 2.75, followed by foot disability (3.26 +/- 2.91) and difficulty performing activities (1.55 +/- 2.22). The final score of the SySQ questionnaire was 0.95 +/- 0.45 (0.18-2.45), and the subscales with the highest score were symptom frequency (1.30 +/- 0.47), symptom intensity (1.11 +/- 0.55), and general skill limitation (0.47 +/- 0.51). A high correlation was observed between the final FFI score and the final SySQ score (r = 0.712; p=<0.001). Also, between foot activity limitation and general skill limitation (r = 0.658; p=<0.001). A moderate correlation was observed between foot pain score and overall symptom intensity (r = 0.482; p=<0.001). Also, between foot disability and overall symptom frequency (r = 0.556; p=<0.001). The multivariate analysis (R2 0.51) showed that the final FFI score had a significant relationship with the final SySQ score (p < 0.001). No significant correlation was found between age (p = 0.15), gender (p = 0.49), BMI (p = 0.74) or time of diagnosis (p = 0.57) and FFI. Conclusion: SS is a disease that affects foot functionality in patients, with a greater impact on the pain scale. There is a correlation between the final FFI score and the final SySQ score, so improving foot functionality could help to improve the overall functionality of the patient with sclerosis.