[1] Guys & St Thomas NHS Trust, Guys Hosp, London, England
[2] Kings Coll Hosp NHS Trust, Orpington Hosp, Dept Rheumatol, Orpington, England
[3] Kings Coll London, Dept Resp Med, London, England
[4] Ulster Univ, Sch Med, Dept Hlth & Life Sci, Northland Rd, Derry Londonderry BT48 7JL, North Ireland