“…General study characteristics were extracted to provide a synthesized understanding of periods of publication, countries of publication, study designs and populations studied (Table 3). Analysis of these themes was drawn from the increased number of studies in certain categories, with a significant portion of studies conducted in the last five years (Fastame et al, 2018;Legrand et al, 2019Legrand et al, , 2021Madrigal-Leer et al, 2020;Nieddu et al, 2020;Pes et al, 2018Pes et al, , 2020Pes et al, , 2021Spencer-Hwang et al, 2018) and being primarily of a cross sectional design and published in the United States (Chan et al, 1997;Legrand et al, 2019;Panagiotokos et al, 2011;Pes et al, 2018Pes et al, , 2020Spencer-Hwang et al, 2018;Willcox et al, 2007bWillcox et al, , 2008 with cross-sectional study designs (11 out of 18, level IV evidence) utilizing questionnaires were the most common research tool (Akisaka et al, 1996;Chan et al, 1997;Deiana et al, 1999;Fastame et al, 2018;Legrand et al, 2019;Legrand et al, 2021;Madrigal-Leer et al, 2020;Nieddu et al, 2020;Panagiotakos et al, 2011;Pes et al, 2013Pes et al, , 2018. Populations that were investigated most commonly were Okinawan resident centenarians (Akisaka et al, 1996;Chan et al, 1997;Willcox et al, (2007a)) and centenarian residents of municipalities in Sardinia (Deiana et al, 1999;Pes et al, 2013;Poulain et al, 2004).…”