<qa>  What is the most effective drug?Diffuse cutaneous systemic sclerosis SSc is a rare autoimmune disease characterised by excessive connective tissue in the skin causing skin thickening called scleroderma, muscle, joints and internal organs. A number of different drugs with effects on the immune system known as immunosuppressants are currently being used by clinicians in the treatment of early diffuse cutaneous SSc, but all can have significant side effects. We want to know whether any one is definitely effective and, if so, which is the most effective. 