Letters to the Editor / JAMDA 16 (2015) 258e261

Second, psychosocial resources may serve as mediators of the relationship between frailty and adverse outcomes. Mediation analyses tell us why or how psychosocial resources affect clinical outcomes in frail older people, because mediator variables are usually in the causal pathway between predictors and outcomes.10 It is possible that frailty alters the psychosocial resources of individuals and makes them even more vulnerable to adverse outcomes. Mediation analyses test the extent to which a mediator accounts for the effects of the predictor (frailty) on the outcomes.10 A recent article investigating the mediation effects of several factors on frailty found that although social participation increased the likelihood of frailty worsening, the worsening of frailty was not able to be explained by social participation, or lack thereof.13 However, no studies have yet looked at psychosocial resources as mediators of the association of frailty with adverse outcomes. All in all, it is likely that psychosocial resources are both moderators and mediators of frailty. However, with so little research in existence, no conclusive results can be drawn. Moreover, the 2 studies known to date have used only relatively short follow-up periods (3 years). Given the long life-course progression of psychosocial resources14 and frailty,15 it is likely that both moderation and mediation effects will become more evident with longer-term follow-up. Subsequently, a need exists to investigate the long-term protective effect of psychosocial resources on frailty, particularly using mediation effect studies. Gaining a more comprehensive understanding of how an older person handles frailty, whether by the use of coping mechanisms, having a strong sense of self-control, or an involvement in social support networks, can be used to tailor patient-centered care and potentially reduce the burden associated with frailty.

References 1. Rodriguez-Manas L, Feart C, Mann G, et al. Searching for an operational definition of frailty: A Delphi method based consensus statement: The frailty operative definition-consensus conference project. J Gerontol A Biol Sci Med Sci 2013;68:62e67. 2. Morley JE, Vellas B, van Kan GA, et al. Frailty consensus: A call to action. J Am Med Dir Assoc 2013;14:392e397. 3. Morley JE, Malmstrom TK. Frailty, sarcopenia, and hormones. Endocrinol Metab Clin North Am 2013;42:391e405. 4. Cooper R, Huisman M, Kuh D, Deeg DJ. Do positive psychological characteristics modify the associations of physical performance with functional decline and institutionalization? Findings from the longitudinal aging study Amsterdam. J Gerontol B Psychol Sci Soc Sci 2011;66:468e477. 5. Taylor SE, Seeman TE. Psychosocial resources and the SES-health relationship. Ann N Y Acad Sci 1999;896:210e225. 6. Sanchez-Garcia S, Sanchez-Arenas R, Garcia-Pena C, et al. Frailty among community-dwelling elderly Mexican people: Prevalence and association with sociodemographic characteristics, health state and the use of health services. Geriatr Gerontol Int 2014;14:395e402. 7. Andrew MK, Fisk JD, Rockwood K. Psychological well-being in relation to frailty: A frailty identity crisis? Int Psychogeriatr 2012;24:1347e1353. 8. Gobbens RJ, van Assen MA, Luijkx KG, et al. Determinants of frailty. J Am Med Dir Assoc 2010;11:356e364. 9. Clegg A, Young J, Iliffe S, et al. Frailty in elderly people. Lancet 2013;381: 752e762. 10. Baron RM, Kenny DA. The moderator-mediator variable distinction in social psychological research: Conceptual, strategic, and statistical considerations. J Pers Soc Psychol 1986;51:1173e1182. 11. Dent E, Hoogendijk EO. Psychosocial factors modify the association of frailty with adverse outcomes: A prospective study of hospitalised older people. BMC Geriatr 2014;14:108. 12. Hoogendijk EO, van Hout HPJ, van der Horst HE, et al. Do psychosocial resources modify the effects of frailty on functional decline and mortality? J Psychosom Res 2014;77:547e551, http://dx.doi.org/10.1016/j.jpsychores. 2014.09.017. 13. Etman A, Kamphuis CB, van der Cammen TJ, et al. Do lifestyle, health and social participation mediate educational inequalities in frailty worsening? Eur J Public Health; 2014 [Epub ahead of print]. 14. Pearlin LI, Nguyen KB, Schieman S, Milkie MA. The life-course origins of mastery among older people. J Health Soc Behav 2007;48:164e179.

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15. Alvarado BE, Zunzunegui MV, Beland F, Bamvita JM. Life course social and health conditions linked to frailty in Latin American older men and women. J Gerontol A Biol Sci Med Sci 2008;63:1399e1406.

Elsa Dent, PhD, BAppSc (Hons) Discipline of Public Health The School of Population Health The University of Adelaide, Adelaide, Australia Emiel O. Hoogendijk, MSc Gérôntopole, Toulouse University Hospital Toulouse, France http://dx.doi.org/10.1016/j.jamda.2014.11.014

Searching for a Polypharmacy Threshold Associated With Frailty To the Editor: Polypharmacy is a major health issue, particularly in older people in nursing homes.1e5 It has been identified as an area in nursing homes in which there is a major need for research.6 Further, frailty has been identified as a major precursor to disability and mortality.7 Five cross-sectional studies (4 Australian and 1 Chinese) have assessed the link between polypharmacy and frailty status in various populations.8e12 Of them, 4 demonstrated a significant association.8e10,12 All of these studies used Fried et al’s criteria13 to define frailty, but polypharmacy definition varied between 4 and 6.5 drugs. These thresholds were arbitrarily chosen except in the study by Gnjidic et al.8 In this work, the authors defined the threshold of 6.5 drugs by using a receiver operating characteristics (ROC) curve and the Youden index. The study was performed in Australian community-dwelling men of 70 years and older; this threshold deserves to be confirmed in other countries and in cohorts including both men and women. Our study was aimed at assessing the threshold of polypharmacy associated with frailty in an elderly population in France. We carried out a cross-sectional study that included all the patients consulting for the first time at the Geriatric Frailty Clinic for Assessment of Frailty and Prevention of Disability in Toulouse, France, from January 2013 to October 2013. This clinic is aimed at detecting frail or prefrail status, performing a comprehensive geriatric assessment, and organizing a plan of care in patients older than 65 years referred by their general practitioner.14 A standardized assessment of medical history, comorbidities, drug exposures, and cognitive status is completed and prospectively computerized. Frailty was defined by 3 or more of Fried et al’s criteria.13 We counted the number of drugs (including topical forms) at the time of visit for each patient. A regression logistic model assessing the link between the number of drugs and frailty was used to build a ROC curve. The threshold for polypharmacy was defined by the number of drugs with the maximal value of the Youden index. The Youden index is (sensitivity þ specificity  1) and corresponds to the maximal effectiveness of the marker.15 The association of polypharmacy thresholds (ranging from 4 to 12) with frailty in a multivariate logistic regression model adjusted for age, gender, cognitive impairment (Mini-Mental State Examination [MMSE]

Searching for a polypharmacy threshold associated with frailty.

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