Unique clinical and autoantibody profile of a large Asian Indian cohort of scleroderma-do South Asians have a more aggressive disease?

Abstract

Aim and methods: A single-centre retrospective study was conducted using electronic medical records (EMR) of inpatients and outpatients with the diagnosis of "scleroderma" or "systemic sclerosis" visiting our clinic over the preceding 5 years.

Results: A total of 327 patients' charts met our selection criteria; 301 were females. The median (IQR (inter quartile range)) age at onset of first non-Raynaud's symptom was 34.67 (27-43) years and median (IQR) disease duration prior to presentation to our department was 2.5 (1-5) years. Of these, 310 (94.8%) belonged to diffuse systemic sclerosis variety, 13 (4%) had limited systemic sclerosis, and 4 (1.2%) were of sine scleroderma type. A total of 289/302 (95.7%) patients were positive for ANA; of them, 245/327 (74.9%) were Scl-70 antibody-positive and 4% were CENP antibody-positive. Interstitial lung disease (ILD) was present in 288/327 (88.1%) patients. Among patients with available baseline forced vital capacity (FVC) data, 20% had a normal lung function and 28.4% had severe restriction. Pulmonary hypertension as assessed by echocardiography was present in 8.1% of patients. A significant association of Scl-70 antibody positivity with the presence of interstitial lung disease (ILD) (p = 0.000) and pulmonary hypertension (p = 0.035) was seen. On the other hand, presence of CENP antibody showed a protective trend against muscle weakness and/or muscle enzyme elevation (p = 0.052). Presence of arthritis was protective against development of digital ulceration (p = 0.021) and PAH (0.004). Patients younger than 40 years of age had significantly higher frequency of Scl-70 positivity (p = 0.038), whereas CENP antibody positivity was more likely in those aged > 40 years (p = 0.002).

Conclusion: Younger age of onset and high prevalence of Scl-70 antibody are unique South Asian features common with large Indian, Thai, and Chinese series. High prevalence of ILD is a feature common to Indian and Chinese series. Strong correlation of Scl-70 antibody with younger age and pulmonary hypertension were unique features of our cohort.

Key points: • Asian Indian scleroderma patients are younger by 2 decades compared to Caucasian series. • Higher prevalence of Scl-70 antibody, its association with young age, interstitial lung disease and pulmonary hypertension are features of our cohort. • High prevalence of interstitial lung disease (88.1%) was noted ; among those with baseline spirometry data (141/327), two thirds(66%) had moderate to severe restriction. • Younger age at onset, higher prevalence of Scl-70 antibody are features common to other Indian, Thai and Chinese series.

Keywords: Anti-Scl-70 antibody; Interstitial lung disease; Pulmonary arterial hypertension; Scleroderma; Younger.