Frailty as deficit accumulation
Kenneth Rockwood MD, FRCPC, FRCPDivision of Geriatric Medicine
Dalhousie University & Capital District Health AuthorityHalifax, Canada
Read it as: Rockwood K, Mitnitski A: Frailty defined by deficit accumulation and geriatric medicine defined by frailty. Clinics in Geriatric Medicine 2011 Feb;27(1):17‐26.
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 …
3
Rockwood et al. Can Med Association 1994; 150:499-507Rockwood et al. J Am Geriatric Society 1996; 44:578-82
Health
Attitudes towardHealth and
health practices
Resources
Caregiver
Illness
Disability
Dependence on Others
Burden on the caregiver
Frailty is complex and dynamic
5
Operationalizing frailtyVariables are highly specified:
prototype is the frailty phenotype– Slow mobility– Weakness– Weight loss– Decreased activities– Exhaustion
• Fried et al.,. 2001;56 J Gerontol A Biol Sci Med Sci (3):M146-56.
Variables are hardly specified: prototype is the Frailty Index– Count health deficits (30-100)
• age associated but does not saturate;
• associated with adverse outcome
• <5% missing data– Divide by the number of deficits
considered.• Mitnitski et al., ScientificWorldJ
2001;1:323-326.• Searle et al., BMC Geriatr 2008;8:24.
6
The building blocks of life do not age
http://www.cerritos.edu/earth-science/images/radioa1.gif
Frailty as deficit accumulation: with age, most problems become more common
(Canadian National Population Health Survey, n= 66,580)
0 20 40 60 80 1000
0.1
0.2
0.3
0.4
0.5
0.6
0.7
arthritis
0 20 40 60 80 1000
0.02
0.04
0.06
0.08
0.1
0.12
0.14vision problems
0 20 40 60 80 1000
0.05
0.1
0.15
0.2
0.25
0.3
0.35Mobility disability
0 20 40 60 80 1000
0.02
0.04
0.06
0.08
0.1
0.12
0.14
thyroid problems
Age (years)
Rockwood & Mitnitski Rev Clin Gerontol 2007;18:1-12.
The frailty index is calculated as:
The number of deficits that an individual has
The total number of deficits considered
10 deficits present in an individual = Frailty index score of 10/40 =0.25
40 deficits considered in total
9
Table 1. List of deficits used in the frailty index.
DeficitsLevels
1 Eyesight 52 Hearing 53 Help to eat 34 Help to dress 35 Ability to take care of appearance 36 Help to walk 37 Help to get in and out of bed 38 Help to go to the bathroom 39 Help to take a bath or shower 310 Help to use the telephone 311 Help to travel beyond walking distance 312 Help with shopping 313 Help to prepare own meals 314 Help to do housework 315 Ability to take medications 316 Ability to handle own money 317 Self-rated health 518 Troubles prevent normal activities 319 Lives alone 220 Having a cough 221 Feeling tired 222 Nose stuffed up or sneezing 223 High blood pressure 224 Heart and circulation problems 225 Stroke or effects of stroke 226 Arthritis or rheumatism 227 Parkinson’s disease 228 Eye trouble 229 Ear trouble 230 Dental problems 231 Chest problems 232 Trouble with stomach 233 Kidney trouble 234 Losing control of bladder 235 Losing control of bowels 236 Diabetes 237 Trouble with feet or ankles 238 Skin problems 239 Fractures 2 40 Trouble with nerves 2
Frailty index distribution
02
46
810
Per
cent
0 .2 .4 .6 .8Frailty Index
• Range = 0 to 0.66, mean 0.16•The higher the Frailty Index, the more
frail the individual
Measuring frailty as anindex of (40) deficits
National Population Health Survey - Mean Frailty Index at each cycle in relation to age
Frai
lty In
dex
(or p
ropo
rtion
of h
ealth
def
icits
)
Age (years)10 20 30 40 50 60 70 80 90 100
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
A
Pro
porti
onal
dis
tribu
tion
Rockwood et al., CMAJ 2011; E-pub April 28
5. Why the deficit count matters: transitions from n deficits to death during 5 years; Canadian Study of Health & Aging, N=8,547
0 5 10 150.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Num ber of deficits, n
The
prob
abilit
y of
dea
th
0 5 10 150.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Num ber of deficits, n
The
prob
abilit
y of
dea
th
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 frailtyIndex of about 0.7
A limit to of the number of deficits suggests exhaustion of reserve capacity – is it operationalizable clinically?
Mitnitski, Bao, Rockwood. Mech Ageing Dev 2006;127:490-3. Rockwood & Mitnitski Mech Ageing Dev 2006;127:494-6.
For men & women, deficit accumulation is highly related with mortality (r>0.95); men have a higher
death rate than women
0
0.2
0.4
0.6
0.8
18-
year
Dea
th R
ate
0.1 0.2 0.3 0.4 0.5 0.6 0.70
Frailty Index
women
men
Shi et al., BMC Geriatr. 2011 Apr 20;11:17
Mitnitski, et al., J Am Geriatr Soc, 2005;53:2184-9
Mea
n ac
cum
ulat
ion
of d
efic
its
Legend
65 70 75 80 85 90 95
ALSACSHA-screenCSHA-examNHANESNPHSSOPSBreast cancerCSHA-instMyoc InfarctUS-LTHSH70-75
0.1
0.2
0.3
0.5
1.0
0.05
Age (years)
Clinical and institutional samples, n=2,573
The slope is ~0.03Community samplesn=33,559
Log scale
Deficits accumulate characteristically, both between groups (community vs. institution/ clinical) and within groups*
Slope <0.01
15
Failure kinetics of systems with different levels of redundancy
From Gavrilov & Gavrilova Sci Aging Knowledge Env, 2003; 28:1-10
The rate of deficit accumulation slows as the value of the Frailty Index (here based on Comprehensive
Geriatric Assessment) increasesLo
g of
the
Frai
lty In
dex
Age, years
70 75 80 85 90 95 100-3
-2.5
-2
-1.5
-1
-0.5
0
Rockwood, Rockwood, Mitnitski., J Am Geriatrics Soc, 2010;58:318-323
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80
100
200
300
400
500
600
700
800
900
Frailty Index
Cou
nt
Distribution of Frailty Indexes at Each Wave
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80
0.02
0.04
0.06
0.08
0.1
0.12
0.14
Frailty Index
Den
sity
Proportional Distribution of Frailty Indexes at Each Wave
Distribution of the Frailty Indexin 4 successive waves of the Chinese Longitudinal Health and Longevity Study;Subjects aged 80-99 years; n= 6664
Bennett et al., submitted
18
5‐year transitions between different states of health (empty circles), replicated 5 years later
(solid circles)*
Legend:Empty circles: CSHA-1 CSHA-2Solid circles: CSHA-2 CSHA-3
Goodness of fitr = 0.99
*Mitnitski, Bao, Rockwood., Mech Ageing Dev 2006, 127;490-493
Number of deficits
0 5 100
0.1
0.2
0 5 100
0.1
0.2
0 5 100
0.1
0.2
0 5 100
0.1
0.2
0 5 100
0.1
0.2
0 5 100
0.1
0.2
0 5 100
0.1
0.2
0 5 100
0.1
0.2
0 5 100
0.1
0.2
0.3
0 5 100
0.1
0.2
0.3
0 5 100
0.1
0.2
0.3
0.3
0.3
The
trans
ition
pro
babi
litie
s
0 5 100
0.1
0.2
0 5 100
0.1
0.2
0 5 100
0.1
0.2
0 5 100
0.1
0.2
0 5 100
0.1
0.2
0 5 100
0.1
0.2
0 5 100
0.1
0.2
0 5 100
0.1
0.2
0 5 100
0.1
0.2
0.3
0 5 100
0.1
0.2
0.3
0 5 100
0.1
0.2
0.3
0.3
0.3
The
trans
ition
pro
babi
litie
s
n=0 n=1 n=2 n=3
n=7n=6n=5n=4
n=8 n=9 n=10
)1(!)( )(
ndn
k
nk PeknP
The model
Four parameters of the model and their Interpretation
0k0 5 10
0
0.2 Average number of deficits given zero deficits at baseline
nn kk 110 10
0
0.2
0.4 The difference between the average number of deficits at the two incremental deficit numbers at baseline
0 10 n
nPP dnd 20lnln The intercept and the slope in the probability of deathas a function of the number of deficits at baseline
How can we assess frailty in older adults who are ill?
Defining frailty by counting deficits: data from a medical history & examination
What is added by a Comprehensive Geriatric Assessment
Learning from other complex systems applications
24
Which patient is the more frail?Which patient is the more acutely ill?
0 10 20 30 40 50 60 700
0.2
0.4
0.6
0.8
1
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
0.1
0.2
0.3
0.40.5
Survival time (months)
Sur
viva
l pro
babi
lity
Rockwood, Rockwood, Mitnitski, J Am Geriatric Soc 2010;58:318-323
Parks et al., J Gerontol Biol Sci, in press, 2011.
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?
28
AcknowledgmentsFunding 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
29
Fig. 1. Cumulative distributions of frailty index scores for people defined as ‘robust’, ‘pre-frail’,
and ‘frail’*
0 0.2 0.4 0.6 0.80
0.2
0.4
0.6
0.8
1
Frailty index value
Cum
ulat
ive
Pro
porti
on
Robust
Pre-frail
Frail
0.30
0.12
0.45
*Rockwood, Andrew, Mitnitski. J Gerontol Med Sc, 2007;62:738-743.
30
Fig. 1. Cumulative distributions of frailty index scores for people defined as ‘robust’, ‘pre-frail’,
and ‘frail’*
0 0.2 0.4 0.6 0.80
0.2
0.4
0.6
0.8
1
Frailty index value
Cum
ulat
ive
Pro
porti
on
Robust
Pre-frail
Frail
0.30
0.12
0.45
*Rockwood, Andrew, Mitnitski. J Gerontol Med Sc, 2007;62:738-743.
31
Fig. 2. Cumulative distributions of frailty index scores by number of phenotypic items present.
0 0.2 0.4 0.6 0.80
0.2
0.4
0.6
0.8
1
Frailty Index value
Cum
ulat
ive
prop
ortio
n
Rockwood , et al., J Gerontol Med Sc, 2007;62:738-743.
0.12
0.22
0.34
0.45
0.54
32
Survival curves by CHS definition (Panel A) and for each CHS level (Panels B-D) by FI value cut-point*)
10 20 30 40 50 60 700
0.2
0.4
0.6
0.8
1
A.
0 10 20 30 40 50 60 700.3
0.4
0.5
0.6
0.7
0.8
0.9
1B. ‘Robust’
0 10 20 30 40 50 60 700.3
0.4
0.5
0.6
0.7
0.8
0.9
1C. ‘Pre-frail’
0 10 20 30 40 50 60 700.3
0.4
0.5
0.6
0.7
0.8
0.9
1
D. ‘Frail’
Rockwood , et al., J Gerontol Med Sc, 2007;62:738-743
FI<0.25
FI>=0.25
FI<0.25
FI>=0.25
FI<0.25
FI>=0.25
FrailPre-frail
Robust
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)
Time (months)
Pro
babi
lity
of a
void
ance
of in
stitu
tiona
l car
e
(n=700)
(n=52)
0 10 20 30 40 50 60 700.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Rockwood, et al., J Gerontol Med Sc, 2007;62(7):738-742.
Frailty Index
Cum
ulat
ive
dist
ribut
ion
0 0.2 0.4 0.60
0.2
0.4
0.6
0.8
1
0 0.2 0.4 0.60
0.2
0.4
0.6
0.8
1
Empirical CDFA B
How crucial are the exact components of the CHS definition of frailty?
Rockwood, et al., J Gerontol Med Sc, 2007;62(7):738-742.
None8.6%
Disability & Comorbidity
48.1%
Only Disability
18.5%
Only Comorbidity
24.8%
None5.2%
Disability & Comorbidity
59.7%
Only Disability
17.5%
Only Comorbidity
17.5%
Prevalence of Disability and Comorbidity in frail older
adults Frailty Index (Frail >0.25FI) Frailty Phenotype (Frail ≥ 3 Phenotypic Frailty
Criteria)
Theou et al. (in preparation)