Clinical trials: types, design, and end-points.

Although the pathogenesis of systemic sclerosis is poorly understood, an increasing number of high quality clinical research trials are attempting to modify the overall disease outcome. Survival has improved, largely through therapies focused on single organs. Candidate outcome measures have been tested and a consensus template for trial design has evolved. The complexity of process in systemic sclerosis renders unlikely that an agent of focused mechanism of therapeutic effect will alter all cardinal features of illness.