[1] Med Univ S Carolina, Div Pulm & Crit Care, Div Rheumatol & Immunol, Charleston, SC 29425 USA
[2] Med Univ S Carolina, Div Pulm & Crit Care, Charleston, SC 29425 USA
[3] Johns Hopkins Univ, Baltimore, MD USA
[4] Royal Free Hosp, Ctr Rheumatol, London NW3 2QG, England