Comparing the predictive accuracy of frailty, comorbidity, and disability for mortality: a 1-year follow-up in patients hospitalized in geriatric wards

Figures & data

Table 1 Operationalization of the 41-item frailty index (FI)

Item	Cutoff point	CGA domain to which the item corresponds
1. Cognition problem	Dementia =1, mild cognitive impairment, no dementia =0.5, no cognitive impairment =0	Cognition
2. Emotion problem	GDS >10=1, 5–10=0.5, 0–4=0	Emotion
3. Impaired vision	Yes =1, no =0	Communication
4. Impaired hearing	Yes =1, no =0	Communication
5. Speaking difficulty	Yes =1, no =0	Communication
6. Mobility difficulty	TUG>19=1, 10–19=0.5, <10=0	Mobility
7. History of falls	More than yearly falls =1, less than yearly falls =0.5, no falls =0	Balance
8. Urinary incontinence	Yes =1, catheter =1, no =0	Bladder function
9. Bowel incontinence	Yes =1, no =0	Bowel function
10. Help with meal preparation	Yes =1, no =0	IADL
11. Help with ordinary housework	Yes =1, no =0	IADL
12. Help with managing finances	Yes =1, no =0	IADL
13. Help with managing medications	Yes =1, no =0	IADL
14. Help with phone use	Yes =1, no =0	IADL
15. Help with shopping	Yes =1, no =0	IADL
16. Help with transportation	Yes =1, no =0	IADL
17. Help with mobility in bed	Yes =1, no =0	ADL
18. Help with transfer	Yes =1, no =0	ADL
19. Help with locomotion inside and outside the home	Yes =1, no =0	ADL
20. Help with dressing	Yes =1, no =0	ADL
21. Help with eating	Yes =1, no =0	ADL
22. Help with toilet use	Yes =1, no =0	ADL
23. Help with personal hygiene	Yes =1, no =0	ADL
24. Help with bathing	Yes =1, no =0	ADL
25. Weight loss	>5% weight change =1, 0.5%–5% weight change =0.5, stable weight =0	Nutrition
26. Self-rating of health	Poor =1, fair =0.75, good =0.25, very good to excellent =0	Self-rating of health
27. Heart attack	Yes =1, suspect =0.5, no =0	Comorbidity
28. Congestive heart failure	Yes =1, suspect =0.5, no =0	Comorbidity
29. Peripheral vascular disease	Yes =1, suspect =0.5, no =0	Comorbidity
30. Stroke	Yes =1, suspect =0.5, no =0	Comorbidity
31. Cancer	Yes =1, suspect =0.5, no =0	Comorbidity
32. Diabetes mellitus	Yes =1, suspect =0.5, no =0	Comorbidity
33. Arthritis	Yes =1, suspect =0.5, no =0	Comorbidity
34. Chronic lung disease	Yes =1, suspect =0.5, no =0	Comorbidity
35. Kidney disease	Yes =1, suspect =0.5, no =0	Comorbidity
36. Constipation	Yes =1, no =0	Comorbidity
37 and 38. Other medical problems	None =0, maximum =2	Comorbidity
39. Anxiety	Yes =1, suspect =0.5, no =0	Comorbidity
40. Alcohol use	Yes =1, suspect =0.5, no =0	Comorbidity
41. Other psychiatric illness	Yes =1, suspect =0.5, no =0	Comorbidity

Abbreviations: CGA, comprehensive geriatric assessment; GDS, Geriatric Depression Scale; TUG, Timed Up and Go Test; IADL, instrumental activities of daily living; ADL, activities of daily living.

Table 2 Clinical characteristics of the total study cohort and the two patient subgroups

Clinical characteristics	All patients (n=305)	Subgroup of patients aged 65–82 years (n=139)	Subgroup of patients aged ≥83 years or older (n=166)	P-value*
Age (years)	82.9±6.4 (n=305)	77.1±3.9 (n=139)	87.7±3.4 (n=166)	<0.001
Female	67.9 (207) (n=305)	66.2 (92) (n=139)	69.3 (115) (n=166)	0.565
Height (cm)	163±9.7 (n=305)	165±9.5 (n=139)	162±9.6 (n=166)	0.005
Weight (kg)	73.2±16 (n=305)	79.3±17 (n=139)	68.0±13 (n=166)	<0.001
BMI (kg/m^2)	27.5±5.6 (n=305)	29.3±6.1 (n=139)	26.0±4.5 (n=166)	<0.001
MMSE (points)	25.5±4.6 (n=299)	25.3±4.2 (n=135)	25.6±4.8 (n=164)	0.359
GDS (points)	2.98±3.0 (n=297)	4.03±3.4 (n=134)	3.93±2.7 (n=163)	0.866
Congestive heart failure	47.5 (145) (n=305)	40.3 (56) (n=139)	53.6 (89) (n=166)	0.020
Heart attack	13.8 (42) (n=305)	10.8 (15) (n=139)	16.3 (27) (n=166)	0.167
Stroke	20.3 (62) (n=305)	20.9 (29) (n=139)	19.9 (33) (n=166)	0.832
Cancer	14.4 (44) (n=305)	10.8 (15) (n=139)	17.5 (29) (n=166)	0.098
Diabetes mellitus	38.4 (117) (n=305)	41.7 (58) (n=139)	35.5 (59) (n=166)	0.269
Lung disease	16.7 (51) (n=305)	22.3 (31) (n=139)	12.0 (20) (n=166)	0.017
Kidney disease	64.9 (198) (n=305)	59.0 (82) (n=139)	69.9 (116) (n=166)	0.047
Urinary incontinence or catheterized	23.6 (72) (n=305)	19.4 (27) (n=139)	27.1 (45) (n=166)	0.116
Bowel incontinence	8.2 (25) (n=305)	4.3 (6) (n=139)	11.4 (19) (n=166)	0.024
More than five medications	96.1 (293) (n=305)	95.7 (133) (n=139)	96.4 (160) (n=166)	0.753
Institutionalized	16.1 (49) (n=305)	10.8 (15) (n=139)	20.5 (34) (n=166)	0.022
CFS-7 (category)	5.34±1.2 (n=305)	5.13±1.2 (n=139)	5.52±1.2 (n=166)	0.007
FI (−)	0.34±0.2 (n=305)	0.32±0.16 (n=139)	0.36±0.15 (n=166)	0.008
FRAIL scale components (number)	1.89±1.2 (n=305)	1.75±1.3 (n=139)	2.02±1.3 (n=166)	0.070
CIRS-G (points)	17.5±5.6 (n=305)	16.7±5.6 (n=139)	18.2±5.5 (n=166)	0.037
Comorbidity-D-FI (−)	0.30±0.1 (n=305)	0.29±0.1 (n=139)	0.31±0.1 (n=166)	0.087
ADL-Katz (points)	2.1±1.9 (n=305)	1.78±1.8 (n=139)	2.34±1.9 (n=166)	0.005
IADL/ADL-D-FI (−)	0.41±0.28 (n=305)	0.38±0.3 (n=139)	0.44±0.3 (n=166)	0.040
Mortality during 1-year follow-up	20.3 (62) (n=305)	13.7 (19) (n=139)	25.9 (43) (n=166)	0.008

Notes: Data shown as mean ± SD (total patient number) or percentage (n) (total patient number).

* P-value reported for comparison of patients aged between 65 and 82 years versus patients aged ≥83 years. (−) indicates no unit of measurement.

Abbreviations: ADL, basic activities of daily living; ADL-Katz, disability burden based on the six ADLs of the Katz index; BMI, body mass index; CFS-7, Canadian Study on Health and Aging Clinical Frailty Scale; GDS, Geriatric Depression Scale; CIRS-G, Cumulative Illness Rating Scale for Geriatrics; Comorbidity-D-FI, Comorbidity domain of the frailty index; IADL, instrumental activities of daily living; IADL/ADL-D-FI, IADL/ADL domain of the frailty index; MMSE, Mini Mental State Examination; FI, frailty index.

Table 3 One-year mortality rates of the patients stratified into different degrees of frailty, comorbidity, or disability according to the different frailty, comorbidity, or disability instruments

Instrument	Category/score	All patients (n=305)	Subgroup of patients aged 65–82 years (n=139)	Subgroup of patients aged ≥83 years (n=166)
CFS-7
	Category 1	NA (n=0)	NA (n=0)	NA (n=0)
	Category 2	0.0% (0) (n=1)	0.0% (0) (n=1)	NA (n=0)
	Category 3	0.0% (0) (n=18)	0.0% (0) (n=12)	0.0% (0) (n=6)
	Category 4	1.5% (1) (n=67)	0.0% (0) (n=34)	3.0% (1) (n=33)
	Category 5	9.5% (7) (n=74)	5.7% (2) (n=35)	12.8% (5) (n=39)
	Category 6	17.7% (14) (n=79)	20.0% (7) (n=35)	15.9% (7) (n=44)
	Category 7	60.6% (40) (n=66)	45.5% (10) (n=22)	68.2% (30) (n=44)
FI
	Score of 0	NA (n=0)	NA (n=0)	NA (n=0)
	Score of 0.001–0.100	0.0% (0) (n=14)	0% (0) (n=10)	0.0% (0) (n=4)
	Score of 0.101–0.200	2.4% (1) (n=42)	4.5% (1) (n=22)	0.0% (0) (n=20)
	Score of 0.201–0.300	7.7% (6) (n=78)	10.0% (4) (n=40)	5.3% (2) (n=38)
	Score of 0.301–0.400	15.2% (10) (n=66)	7.7% (2) (n=26)	20.0% (8) (n=40)
	Score of 0.401–0.500	29.4% (15) (n=51)	22.7% (5) (n=22)	44.5% (10) (n=29)
	Score of 0.501–0.600	55.9% (19) (n=34)	27.3% (3) (n=11)	69.6% (16) (n=23)
	Score of 0.601–0.700	55.0% (11) (n=20)	50.0% (4) (n=8)	58.3% (7) (n=12)
FRAIL scale
	Robust	1.7% (1) (n=58)	0.0% (0) (n=29)	3.4% (1) (n=29)
	Prefrail	14.4% (20) (n=139)	10.6% (7) (n=66)	17.8% (13) (n=73)
	Frail	38.0% (41) (n=108)	27.3% (12) (n=44)	45.3% (29) (n=64)
CIRS-G
	0 points	NA (n=0)	NA (n=0)	NA (n=0)
	1–4 points	NA (n=0)	NA (n=0)	NA (n=0)
	5–8 points	0.0% (0) (n=18)	0.0% (0) (n=11)	0.0% (0) (n=7)
	9–12 points	2.3% (1) (n=44)	4.2% (1) (n=24)	0.0% (0) (n=20)
	13–16 points	13.7% (10) (n=73)	8.6% (3) (n=35)	18.4% (7) (n=38)
	17–20 points	18.9% (14) (n=74)	12.9% (4) (n=31)	23.3% (10) (n=43)
	21–24 points	27.4% (17) (n=62)	25.9% (7) (n=27)	28.6% (10) (n=35)
	25–28 points	57.7% (15) (n=26)	25.0% (2) (n=8)	72.2% (13) (n=18)
	29–32 points	80.0% (4) (n=5)	50.0% (1) (n=2)	100% (3) (n=3)
	33–36 points	33.3% (1) (n=3)	100% (1) (n=1)	0.0% (0) (n=2)
Comorbidity-D-FI
	Score of 0	0.0% (0) (n=1)	0.0% (0) (n=1)	NA (n=0)
	Score of 0.001–0.100	0.0% (0) (n=18)	0.0% (0) (n=9)	0.0% (0) (n=9)
	Score of 0.101–0.200	4.3% (3) (n=69)	2.5% (1) (n=40)	6.9% (2) (n=29)
	Score of 0.201–0.300	20.0% (15) (n=75)	18.5% (5) (n=27)	20.8% (10) (n=48)
	Score of 0.301–0.400	29.5% (26) (n=88)	20.9% (9) (n=43)	37.8% (17) (n=45)
	Score of 0.401–0.500	25.6% (10) (n=39)	0.0% (0) (n=11)	35.7% (10) (n=28)
	Score of 0.501–0.600	53.3% (8) (n=15)	50.0% (4) (n=8)	57.1% (4) (n=7)
ADL-Katz
	No disability	6.3% (5) (n=79)	8.5% (4) (n=47)	3.1% (1) (n =32)
	1 disability	11.6% (8) (n=69)	9.4% (3) (n=32)	13.5% (5) (n=37)
	2 disabilities	19.0% (8) (n=42)	6.2% (1) (n=16)	26.9% (7) (n=26)
	3 disabilities	14.7% (5) (n=34)	7.7% (1) (n=13)	19.0% (4) (n=21)
	4 disabilities	41.5% (17) (n=42)	37.5% (6) (n=16)	42.3% (11) (n=26)
	5 disabilities	38.1% (8) (n=21)	11.1% (1) (n=9)	58.3% (7) (n=12)
	6 disabilities	61.1% (11) (n=18)	50.0% (3) (n=6)	66.7% (8) (n=12)
IADL/ADL-D-FI
	Score of 0	0.0% (0) (n=31)	0.0% (0) (n=17)	0.0% (0) (n=14)
	Score of 0.001–0.100	10.0% (2) (n=20)	9.1% (1) (n=11)	11.1% (1) (n=9)
	Score of 0.101–0.200	5.8% (3) (n=52)	7.1% (2) (n=28)	4.2% (1) (n=24)
	Score of 0.201–0.300	8.0% (2) (n=25)	7.1% (1) (n=14)	9.1% (1) (n=11)
	Score of 0.301–0.400	12.5% (5) (n=40)	14.3% (2) (n=14)	11.5% (3) (n=26)
	Score of 0.401–0.500	36.4% (8) (n=22)	11.1% (1) (n=9)	53.8% (7) (n=13)
	Score of 0.501–0.600	28.2% (11) (n=39)	28.6% (4) (n=14)	28.0% (7) (n=25)
	Score of 0.601–0.700	30.4% (7) (n=23)	22.2% (2) (n=9)	35.7% (5) (n=14)
	Score of 0.701–0.800	48.0% (12) (n=25)	27.3% (3) (n=11)	64.3% (9) (n=14)
	Score of 0.801–0.900	53.8% (7) (n=13)	20.0% (1) (n=5)	75.0% (6) (n=8)
	Score of 0.901–1.000	33.3% (5) (n=15)	28.6% (2) (n=7)	62.5% (3) (n=8)

Note: Data in columns 3–5 are shown as percentage of patients who died (number of patients who died) (number of patients in the group).

Abbreviations: ADL, basic activities of daily living; ADL-Katz, disability burden based on the six ADLs of the Katz index; CFS-7, Canadian Study on Health and Aging Clinical Frailty Scale; FI, frailty index; CIRS-G, Cumulative Illness Rating Scale for Geriatrics; Comorbidity-D-FI, Comorbidity domain of the frailty index; IADL, instrumental activities of daily living; IADL/ADL-D-FI, IADL/ADL domain of the frailty index; NA, not applicable.

Table 4 Unadjusted and adjusted hazard ratios for the risk of 1-year mortality of the patients according to each increment in category or score of 0.1 of the different frailty, comorbidity, or disability instruments

Instrument	All patients (n=305)				Subgroup of patients aged 65–82 years (n=139)				Subgroup of patients aged ≥83 years (n=166)
	HR (95% CI)	P-value	Adj* HR (95% CI)	P-value	HR (95% CI)	P-value	Adj* HR (95% CI)	P-value	HR (95% CI)	P-value	Adj* HR (95% CI)	P-value
CFS-7 (per each category increment)	3.789 (2.681–5.354)	<0.001	3.667 (2.590–5.194)	<0.001	3.871 (2.137–7.011)	<0.001	3.950 (2.124–7.343)	<0.001	3.550 (2.323–5.427)	<0.001	3.485 (2.276–5.337)	<0.001
FI (per each 0.1 score increment)	1.954 (1.644–2.323)	<0.001	1.918 (1.607–2.289)	<0.001	1.763 (1.310–2.371)	<0.001	1.812 (1.323–2.482)	<0.001	2.006 (1.618–2.486)	<0.001	1.981 (1.592–2.464)	<0.001
FRAIL Scale (per each category increment)	3.708 (2.347–5.857)	<0.001	3.570 (2.263–5.631)	<0.001	3.885 (1.714–8.805)	0.001	3.818 (1.658–8.788)	0.002	3.488 (2.012–6.046)	<0.001	3.515 (2.027–6.098)	<0.001
CIRS-G (per each 4 point increment)	1.799 (1.523–2.126)	<0.001	1.763 (1.486–2.091)	<0.001	1.891 (1.362–2.626)	<0.001	1.899 (1.352–2.667)	<0.001	1.710 (1.407–2.078)	<0.001	1.701 (1.390–2.083)	<0.001
Comorbidity-D-FI (per each 0.1 score increment)	1.719 (1.399–2.111)	<0.001	1.727 (1.392–2.144)	<0.001	1.759 (1.231–2.513)	0.002	1.724 (1.184–2.511)	0.005	1.660 (1.285–2.144)	<0.001	1.727 (1.311–2.274)	<0.001
ADL-Katz (per each disability increment)	1.543 (1.352–1.761)	<0.001	1.507 (1.316–1.726)	<0.001	1.405 (1.120–1.764)	0.003	1.427 (1.122–1.813)	0.004	1.585 (1.344–1.870)	<0.001	1.559 (1.317–1.845)	<0.001
IADL/ADL-D-FI (per each 0.1 score increment)	1.335 (1.219–1.462)	<0.001	1.321 (1.202–1.452)	<0.001	1.258 (1.081–1.465)	0.003	1.264 (1.079–1.482)	0.004	1.376 (1.226–1.545)	<0.001	1.364 (1.211–1.536)	<0.001

Note:

* Cox proportional hazard model considering age, female gender, and the instrument, with respect to frailty, comorbidity, or disability.

Abbreviations: Adj, adjusted; ADL, basic activities of daily living; ADL-Katz, disability burden based on the six ADLs of the Katz index; CFS-7, Canadian Study on Health and Aging Clinical Frailty Scale; FI, frailty index; CIRS-G, Cumulative Illness Rating Scale for Geriatrics; Comorbidity-D-FI, Comorbidity domain of the frailty index; IADL, instrumental activities of daily living; IADL/ADL-D-FI, IADL/ADL domain of the frailty index; CI, confidence interval; HR, hazard ratio.

Table 5 Discriminative accuracy and comparison of the discriminative accuracy of the different frailty, comorbidity, or disability instruments (full scales) for 1-year mortality

	AUC (95% CI)	P-value	P-value, AUC 1 vs AUCs 2, 3, 4, 5, 6, and 7	P-value, AUC 2 vs AUCs 1, 3, 4, 5, 6, and 7	P-value, AUC 3 vs AUCs 1, 2, 4, 5, 6, and 7	P-value, AUC 4 vs AUCs 1, 2, 3, 5, 6, and 7	P-value, AUC 5 vs AUCs 1, 2, 3, 4, 6, and 7	P-value, AUC 6 vs AUCs 1, 2, 3, 4, 5, and 7	P-value, AUC 7 vs AUCs 1, 2, 3, 4, 5, and 6
All patients (n=305)
1. CFS-7	0.841 (0.788–0.893)	<0.001	–	0.047	<0.001	0.004	<0.001	<0.001	<0.001
2. FI	0.812 (0.754–0.869)	<0.001	0.047	–	<0.001	0.045	<0.001	<0.001	<0.001
3. FRAIL scale	0.727 (0.661–0.792)	<0.001	<0.001	<0.001	–	0.096	0.489	0.296	0.154
4. CIRS-G	0.770 (0.708–0.913)	<0.001	0.004	0.045	0.096	–	0.041	0.225	0.339
5. Comorbidity-D-FI	0.726 (0.663–0.789)	<0.001	<0.001	<0.001	0.489	0.041	–	0.329	0.208
6. ADL-Katz	0.744 (0.674–0.814)	<0.001	<0.001	<0.001	0.296	0.225	0.329	–	0.232
7. IADL/ADL-D-FI	0.757 (0.695–0.819)	<0.001	<0.001	<0.001	0.154	0.339	0.208	0.232	–
Subgroup of patients aged 65–82 years (n=139)
1. CFS-7	0.844 (0.767–0.922)	<0.001	–	0.003	0.003	0.018	0.006	<0.001	<0.001
2. FI	0.752 (0.639–0.865)	<0.001	0.003	–	0.281	0.456	0.299	0.011	0.044
3. FRAIL scale	0.727 (0.619–0.835)	0.002	0.003	0.281	–	0.285	0.479	0.243	0.313
4. CIRS-G	0.757 (0.650–0.864)	<0.001	0.018	0.456	0.285	–	0.217	0.088	0.162
5. Comorbidity-D-FI	0.724 (0.618–0.830)	0.002	0.006	0.299	0.479	0.217	–	0.231	0.378
6. ADL-Katz	0.668 (0.525–0.812)	0.019	<0.001	0.011	0.243	0.088	0.231	–	0.104
7. IADL/ADL-D-FI	0.703 (0.588–0.818)	0.004	<0.001	0.044	0.313	0.162	0.378	0.104	–
Subgroup of patients aged ≥83 years (n=166)
1. CFS-7	0.834 (0.763–0.904)	<0.001	–	0.394	<0.001	0.036	0.006	0.014	0.039
2. FI	0.840 (0.774–0.907)	<0.001	0.394	–	<0.001	0.016	0.001	0.001	0.002
3. FRAIL scale	0.724 (0.640–0.807)	<0.001	<0.001	<0.001	–	0.165	0.492	0.127	0.063
4. CIRS-G	0.768 (0.689–0.846)	<0.001	0.036	0.016	0.165	–	0.099	0.494	0.339
5. Comorbidity-D-FI	0.725 (0.645–0.806)	<0.001	0.006	0.001	0.492	0.099	–	0.465	0.109
6. ADL-Katz	0.770 (0.691–0.850)	<0.001	0.014	0.001	0.127	0.494	0.465	–	0.246
7. IADL/ADL-D-FI	0.785 (0.711–0.859)	<0.001	0.039	0.002	0.063	0.339	0.109	0.246	–

Abbreviations: ADL, basic activities of daily living; ADL-Katz, disability burden based on the six ADLs of the Katz index; AUC, area under the curve; CFS-7, Canadian Study on Health and Aging Clinical Frailty Scale; FI, frailty index; CIRS-G, Cumulative Illness Rating Scale for Geriatrics; Comorbidity-D-FI, Comorbidity domain of the frailty index; IADL, instrumental activities of daily living; IADL/ADL-D-FI, IADL/ADL domain of the frailty index.