1. United Nations; Department of Economic and Social Affairs. World Population Prospects 2019: methodology of the United Nations population estimates and projections. New York, NY: United Nations; 2019.
2. Cesari M, Theou O. Frailty: the broad view. In: Fillit HM, Rockwood K, Young JB, editors. Brocklehurst's textbook of geriatric medicine and gerontology. Philadelphia, PA: Elsevier; 2017. p. 82-7.
3. Fried LP, Tangen CM, Walston J, Newman AB, Hirsch C, Gottdiener J, et al. Frailty in older adults: evidence for a phenotype. J Gerontol A Biol Sci Med Sci 2001;56:M146-56.
7. Collard RM, Boter H, Schoevers RA, Oude Voshaar RC. Prevalence of frailty in community-dwelling older persons: a systematic review. J Am Geriatr Soc 2012;60:1487-92.
8. O’Caoimh R, Galluzzo L, Rodriguez-Laso A, Van der Heyden J, Ranhoff AH, Lamprini-Koula M, et al. Prevalence of frailty at population level in European ADVANTAGE Joint Action Member States: a systematic review and meta-analysis. Ann Ist Super Sanita 2018;54:226-38.
12. Gill TM, Gahbauer EA, Allore HG, Han L. Transitions between frailty states among community-living older persons. Arch Intern Med 2006;166:418-23.
14. Ferrucci L, Fabbri E, Walston JD. Frailty. In: Halter JB, Ouslander JG, Studenski S, editors. Hazzard's geriatric medicine and gerontology. 7th ed. New York, NY: McGraw-Hill; 2017.
16. Won CW, Lee Y, Choi J, Kim KW, Park Y, Park H, et al. Starting construction of frailty cohort for elderly and intervention study. Ann Geriatr Med Res 2016;20:114-7.
17. World Health Organization. WHO handbook for guideline development. 2nd ed. Geneva, Switzerland: World Health Organization; 2014.
20. Tooth L, Ware R, Bain C, Purdie DM, Dobson A. Quality of reporting of observational longitudinal research. Am J Epidemiol 2005;161:280-8.
22. Ministry of Health & Welfare; Korean Association of Orthopedic Medicine. Adaptation process for developing Korean clinical practice guidelines. Seoul, Korea: Ministry of Health & Welfare; 2011.
23. Diamond IR, Grant RC, Feldman BM, Pencharz PB, Ling SC, Moore AM, et al. Defining consensus: a systematic review recommends methodologic criteria for reporting of Delphi studies. J Clin Epidemiol 2014;67:401-9.
24. Cesari M, Vellas B, Hsu FC, Newman AB, Doss H, King AC, et al. A physical activity intervention to treat the frailty syndrome in older persons-results from the LIFE-P study. J Gerontol A Biol Sci Med Sci 2015;70:216-22.
26. Hoogendijk EO, van Hout HP, Heymans MW, van der Horst HE, Frijters DH, Broese van Groenou MI, et al. Explaining the association between educational level and frailty in older adults: results from a 13-year longitudinal study in the Netherlands. Ann Epidemiol 2014;24:538-44.
27. Woods NF, LaCroix AZ, Gray SL, Aragaki A, Cochrane BB, Brunner RL, et al. Frailty: emergence and consequences in women aged 65 and older in the Women’s Health Initiative Observational Study. J Am Geriatr Soc 2005;53:1321-30.
29. Gale CR, Westbury L, Cooper C. Social isolation and loneliness as risk factors for the progression of frailty: the English Longitudinal Study of Ageing. Age Ageing 2018;47:392-7.
30. Castrejon-Perez RC, Jimenez-Corona A, Bernabe E, Villa-Romero AR, Arrive E, Dartigues JF, et al. Oral disease and 3-year incidence of frailty in mexican older adults. J Gerontol A Biol Sci Med Sci 2017;72:951-7.
31. Iwasaki M, Yoshihara A, Sato N, Sato M, Minagawa K, Shimada M, et al. A 5-year longitudinal study of association of maximum bite force with development of frailty in community-dwelling older adults. J Oral Rehabil 2018;45:17-24.
32. Perez-Tasigchana RF, Leon-Munoz LM, Lopez-Garcia E, Gutierrez-Fisac JL, Laclaustra M, Rodriguez-Artalejo F, et al. Metabolic syndrome and insulin resistance are associated with frailty in older adults: a prospective cohort study. Age Ageing 2017;46:807-12.
33. Megale RZ, Ferreira ML, Ferreira PH, Naganathan V, Cumming R, Hirani V, et al. Association between pain and the frailty phenotype in older men: longitudinal results from the Concord Health and Ageing in Men Project (CHAMP). Age Ageing 2018;47:381-7.
34. Liljas AE, Carvalho LA, Papachristou E, De Oliveira C, Wannamethee SG, Ramsay SE, et al. Self-reported vision impairment and incident prefrailty and frailty in English community-dwelling older adults: findings from a 4-year follow-up study. J Epidemiol Community Health 2017;71:1053-8.
35. Liljas AE, Carvalho LA, Papachristou E, Oliveira C, Wannamethee SG, Ramsay SE, et al. Self-reported hearing impairment and incident frailty in English community-dwelling older adults: a 4-year follow-up study. J Am Geriatr Soc 2017;65:958-65.
36. Yuki A, Otsuka R, Tange C, Nishita Y, Tomida M, Ando F, et al. Polypharmacy is associated with frailty in Japanese community-dwelling older adults. Geriatr Gerontol Int 2018;18:1497-500.
39. Kojima G, Iliffe S, Jivraj S, Liljas A, Walters K. Does current smoking predict future frailty?: the English longitudinal study of ageing. Age Ageing 2018;47:126-31.
40. Leon-Munoz LM, Guallar-Castillon P, Lopez-Garcia E, Rodriguez-Artalejo F. Mediterranean diet and risk of frailty in community-dwelling older adults. J Am Med Dir Assoc 2014;15:899-903.
41. Garcia-Esquinas E, Rahi B, Peres K, Colpo M, Dartigues JF, Bandinelli S, et al. Consumption of fruit and vegetables and risk of frailty: a dose-response analysis of 3 prospective cohorts of community-dwelling older adults. Am J Clin Nutr 2016;104:132-42.
42. Lana A, Rodriguez-Artalejo F, Lopez-Garcia E. Dairy consumption and risk of frailty in older adults: a prospective cohort study. J Am Geriatr Soc 2015;63:1852-60.
43. Sandoval-Insausti H, Perez-Tasigchana RF, Lopez-Garcia E, Garcia-Esquinas E, Rodriguez-Artalejo F, Guallar-Castillon P. Macronutrients intake and incident frailty in older adults: a prospective cohort study. J Gerontol A Biol Sci Med Sci 2016;71:1329-34.
44. Balboa-Castillo T, Struijk EA, Lopez-Garcia E, Banegas JR, Rodriguez-Artalejo F, Guallar-Castillon P. Low vitamin intake is associated with risk of frailty in older adults. Age Ageing 2018;47:872-9.
45. Ferrucci L, Orini S. Comprehensive geriatric assessment: an updated perspective. In: Pilotto A, Martin FC, editors. Comprehensive geriatric assessment. Cham, Switzerland: Springer International Publishing; 2017.