1 Unit of Biostatistics, IRCCS Casa Sollievo della Sofferenza Hospital, San Giovanni Rotondo, Italy.
2 Unit of Biostatistics, IRCCS Casa Sollievo della Sofferenza Hospital, San Giovanni Rotondo, Italy; Unit of Biostatistics, Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy.
3 Liver Unit, IRCCS Casa Sollievo della Sofferenza Hospital, San Giovanni Rotondo, Italy.
4 Liver Unit, IRCCS Casa Sollievo della Sofferenza Hospital, San Giovanni Rotondo, Italy. Electronic address: a.mangia@tin.it.