The relationship between smoking, Raynaud's phenomenon, digital ulcers, and skin thickness in the Waikato Systemic Sclerosis cohort
Authors: Silva Cherumi , Solanki Kamal K. , White Douglas H.N. 
Published: July 2022

Abstract

Objectives
Systemic sclerosis (SSc) is a heterogeneous complex autoimmune connective tissue disease with variable presentation as a consequence of multisystem involvement. One of the key features of SSc is Raynaud's phenomenon along with vascular endothelial dysfunction that leads to digital ulcers (DUs). Raynaud's tends to be triggered by decreasing thermal gradient exposure, while stress and smoking also play a role. DUs arising as a consequence of severe Raynaud's and vasculopathy are a major cause of morbidity and disability in SSc. We set out to determine the relationship between smoking, Raynaud's phenomenon, DUs, and skin thickness in our Waikato Systemic Sclerosis cohort.

Methods
The Waikato Systemic Sclerosis (SSc) database was used to extract data. Variables collected included demographics, age of diagnosis, SSc subtypes, age at first non-Raynaud's phenomenon, medications used for treatment of Raynaud's phenomenon or ulcers, and maximal modified Rodnan skin score (mRSS). Raynaud's phenomenon and finger DUs (severity for each over the past week and since diagnosis) and a Scleroderma Health Assessment Questionnaire (SHAQ) visual analog 10 cm scale were collected. The lead rheumatologist completed a physician's assessment of Raynaud's and the disease severity questionnaire.

Results
Of the cohort of 143 patients, 100 patients were eligible to complete the questionnaires. Seventy-five patients returned completed questionnaires. Of these, the majority were female (88%), 52 (69.3%) had limited cutaneous systemic sclerosis (lcSSc), 17 (22.7%) had diffuse cutaneous systemic sclerosis (dcSSc), and 6 (8%) had an overlap syndrome. Thirty-six (48%) had a smoking history (in the time frame of collection of serial data). Mean ± standard deviation (SD) pack-years smoked were 17.11 ± 15.29 years. Thirty-five participants had a history of DUs, with a median of 4 DU (range 1–20). Of 17 patients with dcSSc, 12 (70.6%) had ulcers in comparison with 17 of 52 (32.7%) patients with lcSSc. There was a significant relationship between SSc subtype and the number with ulcers (X2
= 10.1, P = 0.007). There was also a significant relationship between physician severity of Raynaud's and presence of ulcers (t = 6.1, P < 0.001), which was not evident between patients’ severity of Raynaud's and presence of ulcers (t = 1.9, P = 0.06). On the SHAQ score, smokers had significantly worse Raynaud's phenomenon over the prior week (t = 3.08, P = 0.03) and were more likely to note DUs over the preceding week, although the latter was not statistically significant (t = 1.95, P = 0.055). There was no association between smoking and skin thickness as measured by mRSS (r = 0.23, P = 0.19).

Conclusion
Our study demonstrates that smokers have had worse Raynaud's phenomenon over the past week and they were also more likely to note DUs with a trend toward significance but not statistically significant most likely due to our small sample size. Our study also demonstrated that patients with dcSSc had more ulcers in comparison with lcSSc. This study justifies physicians strongly recommending smoking cessation in patients with SSc.