Rapid skin thickness progression rate is associated with high incidence rate of cardiopulmonary complications in patients with early diffuse cutaneous systemic sclerosis: inception cohort study.

Objectives: We aimed to investigate patients with early diffuse cutaneous systemic sclerosis (dcSSc) with regard to: 1. the association between skin thickness progression rate (STPR) at baseline visit and incidence rate of cardiopulmonary complications; 2. comparison of the mortality rate between patients with skin improvers and those with skin non-improvers.

Methods: An inception cohort of early dcSSc patients seen at the Rheumatology Clinic, Maharaj Nakorn Chiang Mai Hospital, Thailand, was selected. All patients were assessed for clinical manifestations, and modified Rodnan skin score (mRSS) and underwent echocardiography, and HRCT at study entry and then annually.

Results: One hundred and four dcSSc patients (57 of whom were females and 91 anti-topoisomerase I-positive) with a mean disease duration of 11.1±8.6 months were enrolled. Forty-two patients had rapid STPR [RPsp], 38 intermediate STPR [IMsp] and 24 slow STPR [SLsp]. At enrolment, the RPsp group had a significantly shorter disease duration, more prevalent anti-topoisomerase-I-positive, higher mRSS, more prevalent creatine kinase≥500 IU/L and higher NT-proBNP levels compared to the IMSp and SLsp groups. During a mean observation period of 4.5±2.0 years, the RPsp group had a significantly higher incidence rate of LVEF< 50% (6.06 vs. 0 per 100 person- years, p=<0.01) and interstitial lung disease (ILD) (69.69 vs. 34.66 per 100 person-years, p=0.012) than the SLsp group. Skin non-improvers had a signif- icantly higher mortality rate than skin improvers (28.6% vs. 5.8 %, p= 0.004).

Conclusions: In this early dcSSc study cohort it was found that skin change determined by STPR at the baseline visit was a useful surrogate marker for cardiac and ILD complications. It was also found that skin improvers assessed 1-year later were a useful surrogate marker of mortality.