ABSTRACT
Systemic sclerosis is a multisystem disease that has considerable variability in its presentation, course, and prognosis. The aim of this study was to determine serum levels of platelet-derived growth factor [PDGF A/B] in patients with systemic sclerosis [SSc] and to correlate these levels with the extent of skin sclerosis and presence of pulmonary affection. Moreover, the efficiency of PDGF and skin score in early detection of pulmonary affection were assessed. The study included 22 female patients with SSc [according to the American College of Rheumatology] [Masi et al., 1980] and 15 age-matched healthy control females. According to the classification by LeRoy et al. [1988], we divided our patients into limited SSc [10 patients-45.5%] and diffuse SSc [12 patients-54.5%]. The extent of skin sclerosis was assessed by the modified Rodnan total skin thickness scoring [TSS] system [Clements et al., 1995]. In our study, patients with limited SSc had a skin score <25, while those with diffuse SSc had skin score >25. Five diffuse SSc patients had associated pulmonary affection, diagnosed by history taking, clinical examination, chest x-ray, arterial blood gases, spirometry and diffusing capacity of the lung for carbon monoxide [DLCO]. Serum levels of PPGF were determined in SSc patients and healthy controls using quantitative sandwich ELISA technique. Serum PDGF mean and standard deviation in healthy subjects was 5.2 +/- 2.466 ug/l. PDGF values showed continuous significant increment with progression of the disease. Mean PDGF serum levels in limited SSc, diffuse SSc without pulmonary affection and with pulmonary affection were 15.8 +/- 2.3, 20.86 +/- 2.41 and 32 +/- 3.08 ug/l, respectively. Furthermore, the results revealed that PDGF value <10 ugh, tend to exclude the diagnosis of SSc with 100% sensitivity and specificity, respectively. Moreover, all patients with diffuse SSc and having pulmonary affection had PDGF values >25 ug/l. This value provided a diagnostic sensitivity and specificity of 100%. As regards the total skin score, a statistical significance was found between limited and diffuse SSc but did not show a statistically significant difference between SSc patients with [32.2 +/- 4.49] and without [29.71 +/- 3.25] pulmonary affection [p>0.05]. However, in patients with diffuse SSc, PDGF levels tended to correlate positively with the skin score [p=0.05]. ROC plot showed that skin score at a value of 29 was the best cut-off level to diagnose pulmonary affection in patients with diffuse SSc with a diagnostic sensitivity of 80% and specificity of 71.4%. PDGF is a simple and easy laboratory test that tends to exclude the presence of SSc at a cut-off value of 10ng/ml with 100% sensitivity and specificity, respectively. PDGF correlates positively with extent of skin involvement and significantly with pulmonary affection. PDGF and skin scoring system are simple laboratory and physical measures for evaluating patients with systemic sclerosis with cut-off levels of 25 ug/l, and 29 respectively in detecting pulmonary affection. However, further studies are recommended on larger population to ensure the diagnostic efficiency of PDGF and to test the applicability of our obtained cut-off values