Frailty as deficit accumulation

Transcription

1 Frailty as deficit accumulation Kenneth Rockwood MD, FRCPC, FRCP Division of Geriatric Medicine Dalhousie University & Capital District Health Authority Halifax, Canada Read it as: Rockwood K, Mitnitski A: Frailty defined by deficit accumulation and geriatric medicine defined by frailty. Clinics in Geriatric Medicine 211 Feb;27(1):17 26.

2 Disclosures With colleagues, I am applying to various Canadian government university industry schemes for funding to commercialize a version of the Frailty Index, based on a Comprehensive Geriatric assessment. My colleagues and I are always on the look out for clever young doctors who have undergraduate degrees in engineering, physics, mathematics

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4 Frailty is complex and dynamic Health Attitudes toward Health and health practices Resources Caregiver Illness Disability Dependence on Others Burden on the caregiver Rockwood et al. Can Med Association 1994; 15: Rockwood et al. J Am Geriatric Society 1996; 44:578-82

5 Operationalizing frailty Variables are highly specified: prototype is the frailty phenotype Slow mobility Weakness Weight loss Decreased activities Exhaustion Fried et al.,. 21;56 J Gerontol A Biol Sci Med Sci (3):M Variables are hardly specified: prototype is the Frailty Index Count health deficits (3-1) age associated but does not saturate; associated with adverse outcome <5% missing data Divide by the number of deficits considered. Mitnitski et al., ScientificWorldJ 21;1: Searle et al., BMC Geriatr 28;8:24. 5

6 The building blocks of life do not age 6

7 Frailty as deficit accumulation: with age, most problems become more common (Canadian National Population Health Survey, n= 66,58) vision problems.35.3 Mobility disability arthritis thyroid problems Age (years) Rockwood & Mitnitski Rev Clin Gerontol 27;18:1-12.

8 The frailty index is calculated as: The number of deficits that an individual has The total number of deficits considered 1 deficits present in an individual = Frailty index score of 1/4 =.25 4 deficits considered in total

9 Table 1. List of deficits used in the frailty index. Deficits Levels 1 Eyesight 5 2 Hearing 5 3 Help to eat 3 4 Help to dress 3 5 Ability to take care of appearance 3 6 Help to walk 3 7 Help to get in and out of bed 3 8 Help to go to the bathroom 3 9 Help to take a bath or shower 3 1 Help to use the telephone 3 11 Help to travel beyond walking distance 3 12 Help with shopping 3 13 Help to prepare own meals 3 14 Help to do housework 3 15 Ability to take medications 3 16 Ability to handle own money 3 17 Self-rated health 5 18 Troubles prevent normal activities 3 19 Lives alone 2 2 Having a cough 2 21 Feeling tired 2 22 Nose stuffed up or sneezing 2 23 High blood pressure 2 24 Heart and circulation problems 2 25 Stroke or effects of stroke 2 26 Arthritis or rheumatism 2 27 Parkinson s disease 2 28 Eye trouble 2 29 Ear trouble 2 3 Dental problems 2 31 Chest problems 2 32 Trouble with stomach 2 33 Kidney trouble 2 34 Losing control of bladder 2 35 Losing control of bowels 2 36 Diabetes 2 37 Trouble with feet or ankles 2 38 Skin problems 2 39 Fractures 2 4 Trouble with nerves 2 Measuring frailty as an Percent index of (4) deficits Frailty index distribution Frailty Index Range = to.66, mean.16 The higher the Frailty Index, the more frail the individual 9

10 National Population Health Survey - Mean Frailty Index at each cycle in relation to age.5 Frailty Index (or proportion of health deficits) A Proportional distribution Age (years) Rockwood et al., CMAJ 211; E-pub April 28

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12 5. Why the deficit count matters: transitions from n deficits to death during 5 years; Canadian Study of Health & Aging, N=8,547 The probability of death Of 8,547 people at baseline, only 18 had >17/31 possible deficits, and only 7 (of 5586) had >17/31 at follow-up Survival limit close to the frailty Index of about Number of deficits, n A limit to of the number of deficits suggests exhaustion of reserve capacity is it operationalizable clinically? Mitnitski, Bao, Rockwood. Mech Ageing Dev 26;127:49-3. Rockwood & Mitnitski Mech Ageing Dev 26;127:494-6.

13 For men & women, deficit accumulation is highly related with mortality (r>.95); men have a higher death rate than women 1 8-year Death Rate men women Frailty Index Shi et al., BMC Geriatr. 211 Apr 2;11:17

14 Deficits accumulate characteristically, both between groups (community vs. institution/ clinical) and within groups* Mean accumulation of deficits Log scale Clinical and institutional samples, n=2,573 Community samples n=33,559 The slope is ~ Age (years) Slope <.1 Legend ALSA CSHA-screen CSHA-exam NHANES NPHS SOPS Breast cancer CSHA-inst Myoc Infarct US-LTHS H7-75 Mitnitski, et al., J Am Geriatr Soc, 25;53:2184-9

15 Failure kinetics of systems with different levels of redundancy From Gavrilov & Gavrilova Sci Aging Knowledge Env, 23; 28:1-1 15

16 The rate of deficit accumulation slows as the value of the Frailty Index (here based on Comprehensive Geriatric Assessment) increases Log of the Frailty Index Age, years Rockwood, Rockwood, Mitnitski., J Am Geriatrics Soc, 21;58:

17 Distribution of the Frailty Index in 4 successive waves of the Chinese Longitudinal Health and Longevity Study; Subjects aged 8-99 years; n= 6664 Count Distribution of Frailty Indexes at Each Wave Frailty Index.14 Proportional Distribution of Frailty Indexes at Each Wave.12.1 Density Bennett et al., submitted Frailty Index

18 5 year transitions between different states of health (empty circles), replicated 5 years later (solid circles)*.3.2 n= n=1 n=2 n= The model The transition probabilities n= n=5 5 1 Number of deficits n=6 n=8 n=9 n= n=7 5 1 k ( ( n) Goodness of fit r =.99 Legend: Empty circles: CSHA-1 CSHA-2 Solid circles: CSHA-2 CSHA-3 *Mitnitski, Bao, Rockwood., Mech Ageing Dev 26, ; P nk n) k! e (1 P nd )

19 Four parameters of the model and their Interpretation k Average number of deficits given zero deficits at baseline 1 k n 1 k n.4.2 The difference between the average number of deficits at the two incremental deficit numbers at baseline 1 ln P ln P n nd d 2 The intercept and the slope in the probability of death as a function of the number of deficits at baseline 1 n

20 How can we assess frailty in older adults who are ill?

21 Defining frailty by counting deficits: data from a medical history & examination

22 What is added by a Comprehensive Geriatric Assessment

23 Learning from other complex systems applications

24 Which patient is the more frail? Which patient is the more acutely ill? 24

25 A Frailty Index based on a Comprehensive Geriatric Assessment identifies a group at the highest risk of dying (some of whom live 18 months). FI-CGA Survival probability Survival time (months) Rockwood, Rockwood, Mitnitski, J Am Geriatric Soc 21;58:

26 Parks et al., J Gerontol Biol Sci, in press, 211.

27 Studies of frailty as deficit accumulation. There is remarkable consistency in: how deficits accumulate with age. the limit to how many things can be wrong. how deficit counts change over time. Some clinical lessons: How can we count what people have wrong with them? Does our clinical intuition about the stability of deficit accumulation mislead? 27

28 Acknowledgments Funding sources: Fountain Innovation Fund of the QEII Health Sciences Foundation Canadian Institutes of Health Research Mathematics of Information Technology and Computer Science program, National Research Council Alzheimer Society of Canada National Natural Science Foundation of China Dalhousie Medical Research Foundation Colleagues & students: Arnold Mitnitski Nadar Fallah Xiaowei Song Ruth Hubbard Melissa Andrew Michael Rockwood Samuel Searle Paige Moorhouse, Laurie Mallery 28

29 Fig. 1. Cumulative distributions of frailty index scores for people defined as robust, pre-frail, and frail * 1 Robust Cumulative Proportion Pre-frail Frail Frailty index value *Rockwood, Andrew, Mitnitski. J Gerontol Med Sc, 27;62:

30 Fig. 1. Cumulative distributions of frailty index scores for people defined as robust, pre-frail, and frail * 1 Robust Cumulative Proportion Pre-frail Frail Frailty index value *Rockwood, Andrew, Mitnitski. J Gerontol Med Sc, 27;62:

31 Fig. 2. Cumulative distributions of frailty index scores by number of phenotypic items present. 1 Cumulative proportion Frailty Index value Rockwood, et al., J Gerontol Med Sc, 27;62:

32 Survival curves by CHS definition (Panel A) and for each CHS level (Panels B-D) by FI value cut-point*) Frail A. Robust Pre-frail B. Robust FI< FI>= C. Pre-frail FI< FI<.25 D. Frail.5.4 FI>= FI>= Rockwood, et al., J Gerontol Med Sc, 27;62:

33 Additional comparisons of the CHS definition and the FI: FI stratified by CHS (Panel E); Institutionalization of the Robust stratified by FI (Panel F) 1.9 Probability of avoidance of institutional care (n=7).5 (n=52) Time (months) Rockwood, et al., J Gerontol Med Sc, 27;62(7):

34 How crucial are the exact components of the CHS definition of frailty? A Cumulative distribution Empirical CDF B Frailty Index Rockwood, et al., J Gerontol Med Sc, 27;62(7):

35 Prevalence of Disability and Comorbidity in frail older adults Frailty Index (Frail >.25FI) Frailty Phenotype (Frail 3 Phenotypic Frailty Criteria) Only Comorbidity 24.8% Only Disability 18.5% None 8.6% Disability & Comorbidity 48.1% Only Comorbidity 17.5% Only Disability 17.5% None 5.2% Disability & Comorbidity 59.7% Theou et al. (in preparation)