Erratum to: Smoking, Porphyromonas gingivalis and the immune response to citrullinated autoantigens before the clinical onset of rheumatoid arthritis in a Southern European nested case–control study. Issue 1 (December 2016) - Fisher, Benjamin; Cartwright, Alison; Quirke, Anne-Marie; de Pablo, Paola; Romaguera, Dora; Panico, Salvatore; Mattiello, Amalia; Gavrila, Diana; Navarro, Carmen; Sacerdote, Carlotta; Vineis, Paolo; Tumino, Rosario; et al.