Collaborators: This analysis was conducted as a collaborative work between the MAINTAIN Nephritis Trial investigators and the Lupus Nephritis Trials Network. The MAINTAIN investigators were: Daniel Abramowicz, Nephrology Department, Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium; Fabiola Atzeni, Unita Operativa di Reumatologia, Ospedale Luigi Sacco, Milan, Italy; Daniel Blockmans, General Internal Medicine Department, UZ Gasthuisberg, Katholieke Universiteit Leuven, Leuven, Belgium; Maria Giovanna Danieli, Istituto di Clinica Medica Generale, Universia Degli Study di Ancona, Torrette di Ancona, Italy; Luc De Clercq, Rheumatology Department, Sint-Augustinus Ziekenhuis, Wilrijk, Belgium; David D'Cruz, Louise Coote Lupus Unit, St Thomas’ Hospital, London, UK; Maria del Mar Ayala Guttierez, General Internal Medicine, Hospital Regional Universitario Carlos Haya, Malaga, Spain; Enrique de Ramon Garrido, General Internal Medicine, Hospital Regional Universitario Carlos Haya, Malaga, Spain; Inge-Magrethe Gilboe, Rheumatology Department, Rikshospitalet University Hospital, Oslo, Norway; Filip de Keyser, Rheumatology Department, UZ Gent, University of Ghent, Ghent, Belgium ; Michel Delahousse, Service de Nephrologie, Hôpital Foch, Paris, France; Gerard Espinosa, Department of Autoimmune Diseases, Hospital Clinic, Barcelona, Catalonia, Spain; Christoph Fiehn, ACURA Center for Rheumatic Diseases, Baden-Baden, Germany; Marc Golstein, Service de Rheumatologie, Cliniques Saint-Jean, Brussels, Belgium; Loïc Guillevin, General Internal Medicine Department, Hôpital Cochin, Paris, France; Marco Hirsch, Luxembourg, Grand Duchy of Luxembourg; Alexandre Karras, Service de Néphrologie, Hôpital Européen Georges Pompidou, Paris, France; Philippe Lang, Nephrology Department, Hôpital Henri Mondor, Créteil, France; Véronique le Guern, General Internal Medicine Department, Hôpital Cochin, Paris, France; Martine Marchal, Service de Néphrologie, Hôpital de Tivoli, La Louvière, Belgium; Antonio Marinho, Clinical Immunology Unit, Hospital Santo Antonio, ICBAS, Porto, Portugal; Regina Max, Department of Internal Medicine V, University of Heidelberg, Heidelberg, Germany; Patrick Peeters, Nephrology Department, UZ Gent, University of Ghent, Ghent, Belgium; Peter Petera, Zentrum für Diagnostik und Therapie rheumatischer Erkrankungen, Krankenhaus Lainz, Wien, Austria; Radmila Petrovic, Institute of Rheumatology, University of Belgrade, Belgrade, Serbia; Thomas Quémeneur, Centre Hospitalier Régional Universitaire de Lille, Lille, France; Frank Raeman, Rheumatology Department, Jan Palfijn Hospital, Merksem, Belgium; Philippe Remy, Nephrology Department, Hôpital Henri Mondor, Créteil, France; Isabelle Ravelingien, Rheumatology Department, Onze-Lieve-Vrouw Ziekenhuis, Aalst, Belgium; Piercarlo Sarzi-Puttini, Unita Operativa di Reumatologia, Ospedale Luigi Sacco, Milan, Italy; Shirish Sangle, Louise Coote Lupus Unit, St Thomas’ Hospital, London, UK; Maria Tektonidou, First Department of Internal Medicine, National University of Athens, Athens, Greece; Lucia Valiente de Santis, General Internal Medicine, Hospital Regional Universitario Carlos Haya, Malaga, Spain; Carlos Vasconcelos, Clinical Immunology Unit, Hospital Santo Antonio, ICBAS, Porto, Portugal; Luc Verresen, Nephrology Department, Ziekenhuis Oost-Limburg, Genk, Belgium; Laurence Weiss, Département d'Immunologie, Hôpital Européen Georges Pompidou, Paris, France; René Westhovens, Rheumatology Department, UZ Gasthuisberg, Katholieke Universiteit Leuven, Leuven, Belgium.