JAMDA 16 (2015) 781e783
JAMDA journal homepage: www.jamda.com
Brief Report
Validity and Responsiveness of the FRAIL Scale in a Longitudinal Cohort Study of Older Australian Women Paul A. Gardiner PhD a, b, *, Gita D. Mishra PhD a, Annette J. Dobson PhD a a b
Centre for Longitudinal and Life Course Research, School of Public Health, The University of Queensland, Brisbane, Australia Translating Research into Practice Center, Mater Research Institute, The University of Queensland, Brisbane, Australia
a b s t r a c t Keywords: Frailty validity responsiveness cohort studies longitudinal studies
Background: To assess the validity and responsiveness of the FRAIL scale and investigate whether validity is related to the number of points used on the scale. Methods: Participants were 12,432 women born in 1921e1926 from the Australian Longitudinal Study on Women’s Health; surveyed up to 6 times from 1996 to 2011. The FRAIL scale is a 5-item measure and scored as a 6-, 3-, or 2-point measure. Face validity was determined by assessing relationships with age, construct validity was determined by assessing relationships with measures of disability (activities of daily living and independent activities of daily living), and responsiveness was determined by assessing relationships with changes in self-rated health. Results: The proportion of women who reported their frailty as high (4 or 5 on a scale of 0 to 5) increased with age from 5.6% at age 73e78 years to 16.2% at age 85e90 years. The FRAIL scale was moderately correlated with disability, Spearman’s rho 0.4 for activities of daily living and 0.5 for independent activities of daily living; slightly stronger associations were observed when it was scored as a 6-point measure. Mean change (95% confidence interval) in FRAIL 6-point scores decreased for women who reported improvements in self-rated health between successive surveys; by at least 0.08 (0.01, 0.15) and increased in those women who reported declines in self-rated health by at least 0.64 (0.57, 0.70). Conclusions: The FRAIL scale is valid and responsive and is suitable for use in longitudinal studies of women in their 70s and older. Ó 2015 AMDA e The Society for Post-Acute and Long-Term Care Medicine.
A recent review identified 27 instruments that have been used to assess frailty,1 including the FRAIL scale.2 This scale, developed by the Geriatric Advisory Panel of the International Academy of Nutrition and Aging, can be administered by a brief-interview or constructed from self-report survey data, and is comparable in predicting mortality and disability to other measures of frailty.3e5 As frailty becomes more prevalent with increasing age6 and may also be a reversible state,7 it is important to have a tool that is able to detect changes in frailty in both directions. Therefore, the aim of this study is to assess the validity and responsiveness of the FRAIL scale using data from a longitudinal cohort of older women, who have a high prevalence of
This work was supported by the Australian Government Department of Health; and the Australian National Health and Medical Research Council (Center of Research Excellence #APP1000986). The authors declare no conflicts of interest. * Address correspondence to Paul A. Gardiner, PhD, School of Public Health, The University of Queensland, Level 3, Public Health Building, Herston Rd, Herston, Queensland 4006, Australia. E-mail address: [email protected] (P.A. Gardiner). http://dx.doi.org/10.1016/j.jamda.2015.05.005 1525-8610/Ó 2015 AMDA e The Society for Post-Acute and Long-Term Care Medicine.
frailty.8 A secondary aim is to assess the number of points used for the FRAIL scale.
Methods Study Population The Australian Longitudinal Study on Women’s Health (ALSWH) is a prospective nationwide study investigating factors related to the health and well-being initially of 3 cohorts of Australian women aged 18e23 years, aged 45e50 years, and aged 70e75 years at baseline in 1996. Women were randomly selected from the Medicare database, which covers all citizens and permanent residents of Australia, including refugees and immigrants. When first surveyed in 1996 (S1) 12,432 women born in 1921e1926 participated; subsequent surveys were conducted in 1999 (S2), 2002 (S3), 2005 (S4), 2008 (S5), and 2011 (S6). Full details of the recruitment and response rates are reported elsewhere.9 The ALSWH was approved by the Medical Research Ethics Committee at the University of Queensland and the
782
P.A. Gardiner et al. / JAMDA 16 (2015) 781e783
Human Research Ethics Committee at the University of Newcastle, and informed consent were obtained from all women. Frailty The FRAIL scale2,10 is based on 5 domains: fatigue, resistance, ambulation, illnesses, and loss of weight and was calculated at surveys 2e6 as previously described11 using data from the 36-Item Short Form Health Survey (SF-36) instrument12 and self-reported chronic conditions and weight. Participants were scored 1 for each of these 5 deficits. The FRAIL scale was used as a 6-point scale (FRAIL6: 0; not frail to 5; most frail), 3-point scale (FRAIL3: frail; 3e5, prefrail; 1e2, and healthy; 0)4 and a 2-point scale (FRAIL2: frail; 3e5, healthy; 0e2).11 Disability Disability was assessed at surveys 4e6 from responses to modified forms of the Katz index of independence in activities of daily living (ADL)13 and the Lawton instrumental activity of daily living (IADL) scale.14 Self-Rated Health Self-rated health was measured by a single item from the SF-36 instrument (“In general would you say your health is, excellent; very good; good; fair or poor”).12 Change in self-rated health from one survey to the next was categorized as improved (poor or fair, to good, very good or excellent; good to very good or excellent), same (excellent to excellent or very good; very good to very good or excellent; good to good; fair to fair or poor; poor to fair or poor), or declined (excellent or very good to good, fair or poor; good to fair or poor). Statistical Analysis Face validity was assessed by examining FRAIL scores at different participants’ ages. Construct validity was assessed by examining the correlation of the FRAIL scale with the scores for ADLs and IADLs. Correlation between frailty score (FRAIL6, FRAIL3, and FRAIL2) and disability score (ADLs and IADLs) was assessed with the Spearman rank correlation coefficient, with 95% confidence intervals. Responsiveness was assessed by examining changes in scores of the FRAIL scale in relation to changes in self-rated health from one survey to the next. Complete case analyses were performed using data from each survey (or pair of surveys) for the women who responded and provided data for the relevant variables. All analyses were conducted in Stata v 13.1 (Stata Corporation, College Station TX). Results The numbers of women who provided FRAIL score data at each survey and the proportion of women at each FRAIL6 score at each survey are presented in Figure 1. The figure shows that frailty increased with age (eg, the proportion of women who score a 4 or a 5 on the FRAIL6 scale increased from 5.6% for women aged 73e78 years to 16.2% for women aged 85e90 years). Stronger correlations of frailty with IADLs were observed than of frailty with ADLs (Table 1). Slightly stronger correlations of frailty and disability were observed when FRAIL was scored as a 6-item scale than as a 3- or 2-item scale. FRAIL6 scores from one survey to the next increased in those who reported improvements in self-rated health (Table 2). There was a greater decline in FRAIL6 scores for women who reported their self-
Fig. 1. Number of women who provided FRAIL scale data at surveys 2e6 and the proportion of women with each FRAIL score at those surveys.
rated health had worsened, than in those whose self-rated health remained the same. These findings were observed across all surveys. Discussion Frailty, as measured by the FRAIL scale was associated with increasing age and disability (ADLs and IADLs). The 6-item version of the FRAIL scale was responsive to changes in self-rated health in a population-based sample of older Australian women. Although previous studies have demonstrated the predictive validity of FRAIL scale in relation to new disability and mortality,3,5,11,15,16 this is the first study to assess responsiveness of the scale using longitudinal data and the impact of using a different number of points on the scale. The FRAIL scale was originally described using 3 categories, and this study suggests there is utility in using the scale as a 6-point scale as demonstrated by the stronger relationships with disability. The FRAIL scale was developed for use as a clinical screening tool but has also been used in population-based cohort studies.3,5,11,15,16 The responsiveness suggests the FRAIL scale is likely to be useful in intervention trials; however, responsiveness still needs to be determined in these types of studies. Validity and responsiveness were examined in a sample of older women and this population is known to have higher prevalence of frailty than men8 and younger populations.6 Evidence on the validity and responsiveness of the FRAIL scale is still needed in other populations. The period between the surveys was 3 years, therefore, other studies may be needed to establish responsiveness and validity over shorter or longer time periods. In summary, the brief 5-item FRAIL scale assessed longitudinally demonstrates good face validity against age, construct validity Table 1 Spearman Rank Correlation Coefficient (95% CI) of Frailty and Disability Survey
Frailty
4 FRAIL6 FRAIL3 FRAIL2 5 FRAIL6 FRAIL3 FRAIL2 6 FRAIL6 FRAIL3 FRAIL2 CI, confidence interval.
ADL
IADL
(N ¼ 5104) 0.48 (0.46, 0.50) 0.46 (0.44, 0.48) 0.45 (0.43, 0.47) (N ¼ 3765) 0.48 (0.46, 0.50) 0.45 (0.43, 0.48) 0.44 (0.41, 0.46) (N ¼ 2506) 0.48 (0.45, 0.51) 0.46 (0.43, 0.49) 0.45 (0.41, 0.48)
(N ¼ 5104) 0.58 (0.56, 0.60) 0.56 (0.54, 0.58) 0.52 (0.50, 0.54) (N ¼ 3765) 0.59 (0.57, 0.61) 0.56 (0.54, 0.59) 0.52 (0.49, 0.54) (N ¼ 2583) 0.52 (0.49, 0.55) 0.50 (0.47, 0.53) 0.47 (0.44, 0.50)
P.A. Gardiner et al. / JAMDA 16 (2015) 781e783
783
Table 2 Change in FRAIL Score (Mean, 95% CI) by Change in Self-Rated Health Change in Self-Rated Health
Survey 2e3 (N ¼ 5692)
Survey 3e4 (N ¼ 4191)
Survey 4e5 (N ¼ 3177)
Survey 5e6 (N ¼ 2146)
Improved Same Declined
0.08 (0.15, 0.01) 0.19 (0.16, 0.23) 0.64 (0.57, 0.70)
0.16 (0.27, 0.05) 0.23 (0.19, 0.27) 0.65 (0.58, 0.72)
0.17 (0.27, 0.07) 0.29 (0.24, 0.33) 0.78 (0.69, 0.88)
0.20 (0.34, 0.06) 0.28 (0.22, 0.34) 0.76 (0.65, 0.87)
CI, confidence interval.
compared with measures of disability, and responsiveness compared with other measures of changes in health, suggesting it is suitable for use in longitudinal studies.
Acknowledgments The ALSWH was conceived and developed by groups of interdisciplinary researchers at the Universities of Newcastle and Queensland. The authors thank all participants for their valuable contribution to the study.
References 1. de Vries NM, Staal JB, van Ravensberg CD, et al. Outcome instruments to measure frailty: A systematic review. Ageing Res Rev 2011;10:104e114. 2. Abellan van Kan G, Rolland YM, Morley JE, et al. Frailty: Toward a clinical definition. J Am Med Dir Assoc 2008;9:71e72. 3. Woo J, Leung J, Morley JE. Comparison of frailty indicators based on clinical phenotype and the multiple deficit approach in predicting mortality and physical limitation. J Am Geriatr Soc 2012;60:1478e1486. 4. Malmstrom TK, Miller DK, Morley JE. A comparison of four frailty models. J Am Geriatr Soc 2014;62:721e726.
5. Ravindrarajah R, Lee DM, Pye SR, et al. The ability of three different models of frailty to predict all-cause mortality: Results from the European Male Aging Study (EMAS). Arch Gerontol Geriatr 2013;57:360e368. 6. Gale CR, Cooper C, Aihie Sayer A. Prevalence of frailty and disability: Findings from the English Longitudinal Study of Ageing. Age Ageing 2015;44:162e165. 7. Gill TM, Gahbauer EA, Allore HG, et al. Transitions between frailty states among community-living older persons. Arch Intern Med 2006;166:418e423. 8. Collard RM, Boter H, Schoevers RA, et al. Prevalence of frailty in communitydwelling older persons: A systematic review. J Am Geriatr Soc 2012;60: 1487e1492. 9. Lee C, Dobson AJ, Brown WJ, et al. Cohort Profile: The Australian Longitudinal Study on Women’s Health. Int J Epidemiol 2005;34:987e991. 10. Abellan van Kan G, Rolland Y, Bergman H, et al. The I.A.N.A Task Force on frailty assessment of older people in clinical practice. J Nutr Health Aging 2008;12: 29e37. 11. Lopez D, Flicker L, Dobson A. Validation of the frail scale in a cohort of older Australian women. J Am Geriatr Soc 2012;60:171e173. 12. Ware JE Jr, Sherbourne CD. The MOS 36-item short-form health survey (SF-36). I. Conceptual framework and item selection. Med Care 1992;30:473e483. 13. Katz S, Downs TD, Cash HR, et al. Progress in development of the index of ADL. Gerontologist 1970;10:20e30. 14. Lawton MP, Brody EM. Assessment of older people: Self-maintaining and instrumental activities of daily living. Gerontologist 1969;9:179e186. 15. Morley JE, Malmstrom TK, Miller DK. A simple frailty questionnaire (FRAIL) predicts outcomes in middle aged African Americans. J Nutr Health Aging 2012;16:601e608. 16. Almeida OP, Hankey GJ, Yeap BB, et al. Depression, frailty, and all-cause mortality: A cohort study of men older than 75 years. J Am Med Dir Assoc 2015;16: 296e300.
JAMDA journal homepage: www.jamda.com
Brief Report
Validity and Responsiveness of the FRAIL Scale in a Longitudinal Cohort Study of Older Australian Women Paul A. Gardiner PhD a, b, *, Gita D. Mishra PhD a, Annette J. Dobson PhD a a b
Centre for Longitudinal and Life Course Research, School of Public Health, The University of Queensland, Brisbane, Australia Translating Research into Practice Center, Mater Research Institute, The University of Queensland, Brisbane, Australia
a b s t r a c t Keywords: Frailty validity responsiveness cohort studies longitudinal studies
Background: To assess the validity and responsiveness of the FRAIL scale and investigate whether validity is related to the number of points used on the scale. Methods: Participants were 12,432 women born in 1921e1926 from the Australian Longitudinal Study on Women’s Health; surveyed up to 6 times from 1996 to 2011. The FRAIL scale is a 5-item measure and scored as a 6-, 3-, or 2-point measure. Face validity was determined by assessing relationships with age, construct validity was determined by assessing relationships with measures of disability (activities of daily living and independent activities of daily living), and responsiveness was determined by assessing relationships with changes in self-rated health. Results: The proportion of women who reported their frailty as high (4 or 5 on a scale of 0 to 5) increased with age from 5.6% at age 73e78 years to 16.2% at age 85e90 years. The FRAIL scale was moderately correlated with disability, Spearman’s rho 0.4 for activities of daily living and 0.5 for independent activities of daily living; slightly stronger associations were observed when it was scored as a 6-point measure. Mean change (95% confidence interval) in FRAIL 6-point scores decreased for women who reported improvements in self-rated health between successive surveys; by at least 0.08 (0.01, 0.15) and increased in those women who reported declines in self-rated health by at least 0.64 (0.57, 0.70). Conclusions: The FRAIL scale is valid and responsive and is suitable for use in longitudinal studies of women in their 70s and older. Ó 2015 AMDA e The Society for Post-Acute and Long-Term Care Medicine.
A recent review identified 27 instruments that have been used to assess frailty,1 including the FRAIL scale.2 This scale, developed by the Geriatric Advisory Panel of the International Academy of Nutrition and Aging, can be administered by a brief-interview or constructed from self-report survey data, and is comparable in predicting mortality and disability to other measures of frailty.3e5 As frailty becomes more prevalent with increasing age6 and may also be a reversible state,7 it is important to have a tool that is able to detect changes in frailty in both directions. Therefore, the aim of this study is to assess the validity and responsiveness of the FRAIL scale using data from a longitudinal cohort of older women, who have a high prevalence of
This work was supported by the Australian Government Department of Health; and the Australian National Health and Medical Research Council (Center of Research Excellence #APP1000986). The authors declare no conflicts of interest. * Address correspondence to Paul A. Gardiner, PhD, School of Public Health, The University of Queensland, Level 3, Public Health Building, Herston Rd, Herston, Queensland 4006, Australia. E-mail address: [email protected] (P.A. Gardiner). http://dx.doi.org/10.1016/j.jamda.2015.05.005 1525-8610/Ó 2015 AMDA e The Society for Post-Acute and Long-Term Care Medicine.
frailty.8 A secondary aim is to assess the number of points used for the FRAIL scale.
Methods Study Population The Australian Longitudinal Study on Women’s Health (ALSWH) is a prospective nationwide study investigating factors related to the health and well-being initially of 3 cohorts of Australian women aged 18e23 years, aged 45e50 years, and aged 70e75 years at baseline in 1996. Women were randomly selected from the Medicare database, which covers all citizens and permanent residents of Australia, including refugees and immigrants. When first surveyed in 1996 (S1) 12,432 women born in 1921e1926 participated; subsequent surveys were conducted in 1999 (S2), 2002 (S3), 2005 (S4), 2008 (S5), and 2011 (S6). Full details of the recruitment and response rates are reported elsewhere.9 The ALSWH was approved by the Medical Research Ethics Committee at the University of Queensland and the
782
P.A. Gardiner et al. / JAMDA 16 (2015) 781e783
Human Research Ethics Committee at the University of Newcastle, and informed consent were obtained from all women. Frailty The FRAIL scale2,10 is based on 5 domains: fatigue, resistance, ambulation, illnesses, and loss of weight and was calculated at surveys 2e6 as previously described11 using data from the 36-Item Short Form Health Survey (SF-36) instrument12 and self-reported chronic conditions and weight. Participants were scored 1 for each of these 5 deficits. The FRAIL scale was used as a 6-point scale (FRAIL6: 0; not frail to 5; most frail), 3-point scale (FRAIL3: frail; 3e5, prefrail; 1e2, and healthy; 0)4 and a 2-point scale (FRAIL2: frail; 3e5, healthy; 0e2).11 Disability Disability was assessed at surveys 4e6 from responses to modified forms of the Katz index of independence in activities of daily living (ADL)13 and the Lawton instrumental activity of daily living (IADL) scale.14 Self-Rated Health Self-rated health was measured by a single item from the SF-36 instrument (“In general would you say your health is, excellent; very good; good; fair or poor”).12 Change in self-rated health from one survey to the next was categorized as improved (poor or fair, to good, very good or excellent; good to very good or excellent), same (excellent to excellent or very good; very good to very good or excellent; good to good; fair to fair or poor; poor to fair or poor), or declined (excellent or very good to good, fair or poor; good to fair or poor). Statistical Analysis Face validity was assessed by examining FRAIL scores at different participants’ ages. Construct validity was assessed by examining the correlation of the FRAIL scale with the scores for ADLs and IADLs. Correlation between frailty score (FRAIL6, FRAIL3, and FRAIL2) and disability score (ADLs and IADLs) was assessed with the Spearman rank correlation coefficient, with 95% confidence intervals. Responsiveness was assessed by examining changes in scores of the FRAIL scale in relation to changes in self-rated health from one survey to the next. Complete case analyses were performed using data from each survey (or pair of surveys) for the women who responded and provided data for the relevant variables. All analyses were conducted in Stata v 13.1 (Stata Corporation, College Station TX). Results The numbers of women who provided FRAIL score data at each survey and the proportion of women at each FRAIL6 score at each survey are presented in Figure 1. The figure shows that frailty increased with age (eg, the proportion of women who score a 4 or a 5 on the FRAIL6 scale increased from 5.6% for women aged 73e78 years to 16.2% for women aged 85e90 years). Stronger correlations of frailty with IADLs were observed than of frailty with ADLs (Table 1). Slightly stronger correlations of frailty and disability were observed when FRAIL was scored as a 6-item scale than as a 3- or 2-item scale. FRAIL6 scores from one survey to the next increased in those who reported improvements in self-rated health (Table 2). There was a greater decline in FRAIL6 scores for women who reported their self-
Fig. 1. Number of women who provided FRAIL scale data at surveys 2e6 and the proportion of women with each FRAIL score at those surveys.
rated health had worsened, than in those whose self-rated health remained the same. These findings were observed across all surveys. Discussion Frailty, as measured by the FRAIL scale was associated with increasing age and disability (ADLs and IADLs). The 6-item version of the FRAIL scale was responsive to changes in self-rated health in a population-based sample of older Australian women. Although previous studies have demonstrated the predictive validity of FRAIL scale in relation to new disability and mortality,3,5,11,15,16 this is the first study to assess responsiveness of the scale using longitudinal data and the impact of using a different number of points on the scale. The FRAIL scale was originally described using 3 categories, and this study suggests there is utility in using the scale as a 6-point scale as demonstrated by the stronger relationships with disability. The FRAIL scale was developed for use as a clinical screening tool but has also been used in population-based cohort studies.3,5,11,15,16 The responsiveness suggests the FRAIL scale is likely to be useful in intervention trials; however, responsiveness still needs to be determined in these types of studies. Validity and responsiveness were examined in a sample of older women and this population is known to have higher prevalence of frailty than men8 and younger populations.6 Evidence on the validity and responsiveness of the FRAIL scale is still needed in other populations. The period between the surveys was 3 years, therefore, other studies may be needed to establish responsiveness and validity over shorter or longer time periods. In summary, the brief 5-item FRAIL scale assessed longitudinally demonstrates good face validity against age, construct validity Table 1 Spearman Rank Correlation Coefficient (95% CI) of Frailty and Disability Survey
Frailty
4 FRAIL6 FRAIL3 FRAIL2 5 FRAIL6 FRAIL3 FRAIL2 6 FRAIL6 FRAIL3 FRAIL2 CI, confidence interval.
ADL
IADL
(N ¼ 5104) 0.48 (0.46, 0.50) 0.46 (0.44, 0.48) 0.45 (0.43, 0.47) (N ¼ 3765) 0.48 (0.46, 0.50) 0.45 (0.43, 0.48) 0.44 (0.41, 0.46) (N ¼ 2506) 0.48 (0.45, 0.51) 0.46 (0.43, 0.49) 0.45 (0.41, 0.48)
(N ¼ 5104) 0.58 (0.56, 0.60) 0.56 (0.54, 0.58) 0.52 (0.50, 0.54) (N ¼ 3765) 0.59 (0.57, 0.61) 0.56 (0.54, 0.59) 0.52 (0.49, 0.54) (N ¼ 2583) 0.52 (0.49, 0.55) 0.50 (0.47, 0.53) 0.47 (0.44, 0.50)
P.A. Gardiner et al. / JAMDA 16 (2015) 781e783
783
Table 2 Change in FRAIL Score (Mean, 95% CI) by Change in Self-Rated Health Change in Self-Rated Health
Survey 2e3 (N ¼ 5692)
Survey 3e4 (N ¼ 4191)
Survey 4e5 (N ¼ 3177)
Survey 5e6 (N ¼ 2146)
Improved Same Declined
0.08 (0.15, 0.01) 0.19 (0.16, 0.23) 0.64 (0.57, 0.70)
0.16 (0.27, 0.05) 0.23 (0.19, 0.27) 0.65 (0.58, 0.72)
0.17 (0.27, 0.07) 0.29 (0.24, 0.33) 0.78 (0.69, 0.88)
0.20 (0.34, 0.06) 0.28 (0.22, 0.34) 0.76 (0.65, 0.87)
CI, confidence interval.
compared with measures of disability, and responsiveness compared with other measures of changes in health, suggesting it is suitable for use in longitudinal studies.
Acknowledgments The ALSWH was conceived and developed by groups of interdisciplinary researchers at the Universities of Newcastle and Queensland. The authors thank all participants for their valuable contribution to the study.
References 1. de Vries NM, Staal JB, van Ravensberg CD, et al. Outcome instruments to measure frailty: A systematic review. Ageing Res Rev 2011;10:104e114. 2. Abellan van Kan G, Rolland YM, Morley JE, et al. Frailty: Toward a clinical definition. J Am Med Dir Assoc 2008;9:71e72. 3. Woo J, Leung J, Morley JE. Comparison of frailty indicators based on clinical phenotype and the multiple deficit approach in predicting mortality and physical limitation. J Am Geriatr Soc 2012;60:1478e1486. 4. Malmstrom TK, Miller DK, Morley JE. A comparison of four frailty models. J Am Geriatr Soc 2014;62:721e726.
5. Ravindrarajah R, Lee DM, Pye SR, et al. The ability of three different models of frailty to predict all-cause mortality: Results from the European Male Aging Study (EMAS). Arch Gerontol Geriatr 2013;57:360e368. 6. Gale CR, Cooper C, Aihie Sayer A. Prevalence of frailty and disability: Findings from the English Longitudinal Study of Ageing. Age Ageing 2015;44:162e165. 7. Gill TM, Gahbauer EA, Allore HG, et al. Transitions between frailty states among community-living older persons. Arch Intern Med 2006;166:418e423. 8. Collard RM, Boter H, Schoevers RA, et al. Prevalence of frailty in communitydwelling older persons: A systematic review. J Am Geriatr Soc 2012;60: 1487e1492. 9. Lee C, Dobson AJ, Brown WJ, et al. Cohort Profile: The Australian Longitudinal Study on Women’s Health. Int J Epidemiol 2005;34:987e991. 10. Abellan van Kan G, Rolland Y, Bergman H, et al. The I.A.N.A Task Force on frailty assessment of older people in clinical practice. J Nutr Health Aging 2008;12: 29e37. 11. Lopez D, Flicker L, Dobson A. Validation of the frail scale in a cohort of older Australian women. J Am Geriatr Soc 2012;60:171e173. 12. Ware JE Jr, Sherbourne CD. The MOS 36-item short-form health survey (SF-36). I. Conceptual framework and item selection. Med Care 1992;30:473e483. 13. Katz S, Downs TD, Cash HR, et al. Progress in development of the index of ADL. Gerontologist 1970;10:20e30. 14. Lawton MP, Brody EM. Assessment of older people: Self-maintaining and instrumental activities of daily living. Gerontologist 1969;9:179e186. 15. Morley JE, Malmstrom TK, Miller DK. A simple frailty questionnaire (FRAIL) predicts outcomes in middle aged African Americans. J Nutr Health Aging 2012;16:601e608. 16. Almeida OP, Hankey GJ, Yeap BB, et al. Depression, frailty, and all-cause mortality: A cohort study of men older than 75 years. J Am Med Dir Assoc 2015;16: 296e300.
