1. National Institute on Aging (NIA) (2018) Available at: https://www.nia.nih.gov. Accessed 22 May 2019
2. ISTAT: Stime per l’anno 2016. 2017, Available at: http://www4.istat.it/it/anziani. Accessed April 1, 2019
3. Pisano M, Ceresoli M, Cimbanassi S, Gurusamy K, Coccolini F, Borzellino G, Costa G, Allievi N, Amato B, Boerma D, Calcagno P, Campanati L, Campanile FC, Casati A, Chiara O, Crucitti A, di Saverio S, Filauro M, Gabrielli F, Guttadauro A, Kluger Y, Magnone S, Merli C, Poiasina E, Puzziello A, Sartelli M, Catena F, Ansaloni L (2019) 2017 WSES and SICG guidelines on acute calcolous cholecystitis in elderly population. World J Emerg Surg. https://doi.org/10.1186/s13017-019-0224-7
4. Costa G, Tomassini F, Tierno SM, Venturini L, Frezza B, Cancrini G, Mero A, Lepre L (2009) Emergency colonic surgery: analysis of risk factors predicting morbidity and mortality. Chir Ital 61:565–571
5. Poillucci G, Podda M, Pisanu A, Mortola L, Dalla Caneva P, Massa G, Costa G, Savastano R, Cillara N, ERASO (Elderly Risk Assessment And Surgical Outcome) Collaborative Study Group (2019) Risk factors for postoperative morbidity following appendectomy in the elderly: a nationwide prospective cohort study. Eur J Trauma Emerg Surg 69:531–540