Predicting time to full-time care in AD: a new model

Figures & data

Table 1.  Baseline characteristics of the cohort included in the analysis.

Socio-demographics
Population in analysis [n (%)]	117 (100%)
Age [mean ± SD]	79.8 ± 7.5
Women [n (%)]	81 (69.2%)
Married [n (%)]	56 (47.9%)
Living alone [n (%)]	47 (40.2%)
Secondary level education [n (%)]	98 (83.8%)
Born in UK [n (%)]	96 (82.1%)
White British [n (%)]	100 (83.5%)
English mother tongue [n (%)]	104 (88.9%)
AD clinical characteristics at baseline
Non-dependent but some functional impairment	47 (40.2%)
Severity of AD (based on MMSE score)
Mild (MMSE > 19) [n (%)]	69 (59.0%)
Moderate (MMSE 10–19) [n (%)]	43 (36.8%)
Severe (MMSE 0–9) [n (%)]	5 (4.3%)
Cognitive and functional ability
ADAS-cog [mean ± SD]	27.2 ± 12.2
ADCS-ADL [mean ± SD]	52.3 ± 13.6
NPI total and domain scores
Total [mean ± SD]	15.7 ± 12.8
Delusion [mean ± SD]	1.0 ± 2.0
Hallucination [mean ± SD]	0.4 ± 1.3
Agitation [mean ± SD]	1.1 ± 1.9
Depression [mean ± SD]	1.5 ± 2.4
Anxiety [mean ± SD]	1.5 ± 2.3
Euphoria [mean ± SD]	0.3 ± 1.2
Apathy [mean ± SD]	2.7 ± 3.7
Reduced inhibition [mean ± SD]	0.5 ± 1.6
Irritability [mean ± SD]	1.6 ± 2.6
Motor behaviour [mean ± SD]	1.9 ± 3.0
Night-time behaviour [mean ± SD]	1.4 ± 2.8
Eating disorders [mean ± SD]	1.6 ± 3.1
Global evaluations
CIBIC-plus [mean ± SD]	3.6 ± 0.7
BGP [mean ± SD]	10.7 ± 6.4
AD-related treatments at baseline
Acetylcholinesterase inhibitors [n (%)]	84 (71.8%)
Antipsychotic treatment [n (%)]	11 (9.4%)
Medical history
Coronary artery bypass graft [n (%)]	4 (3.4%)
Atrial fibrillation [n (%)]	7 (6.0%)
Hypertension [n (%)]	42 (35.9%)
Stroke or transient ischaemic attack [n (%)]	9 (7.7%)
Myocardial infarction [n (%)]	8 (6.8%)
Diabetes [n (%)]	7 (6.0%)
Vascular dementia [mean HIS score ± SD]	0.85 ± 0.93
Caregiver information
Age [mean ± SD]	65.1 ± 13.5
Women [n (%)]	76 (65.0%)
Living with patient [n (%)]	67 (57.3%)
Relation to patient [n (%)]
Spouse	54 (46.2%)
Relative	59 (50.4%)
Paid	4 (3.4%)
Caregiver time
Basic tasks [mean ± SD]	41.2 ± 104.8
Instrumental tasks [mean ± SD]	134.9 ± 184.7
Supervision [mean ± SD]	157.0 ± 266.8
Depression and anxiety (HADS) (n = 87)
Depression [mean ± SD]	5.1 ± 4.1
Anxiety [mean ± SD]	6.8 ± 4.2

AD, Alzheimer's disease; ADAS–cog, AD Assessment Scale–Cognitive subscale; ADCS–ADL, AD Cooperative Study–Activities of Daily Living Scale; HIS, Haschinski Ischaemia Score; NPI, Neuropsychiatric Inventory.

Figure 1. Observed risk of FTC. Vertical axis: observed risk of FTC; horizontal axis labelled: time (months); FTC, need for full-time care.

Figure 2. Proportion of patients remaining free of FTC: observed (lifetable analysis) and basic predictive equation (based only on time). Vertical axis: proportion of patients free of FTC; horizontal axis: time (months); FTC, need for full-time care.

Table 2.  Static and dynamic factors included in the predictive equation.

Parameters	Coefficient	SE	p-value	95% CI
Logarithm of time	3.320	0.497	<0.0001	2.346, 4.292
Baseline ADAS-cog total score	0.033	0.015	0.0247	0.004, 0.061
Baseline ADCS-ADL total score	−0.088	0.016	<0.0001	−0.119, −0.055
Baseline NPI total score	0.038	0.015	0.0140	0.007, 0.067
ADAS-cog slope	0.812	0.280	0.0037	0.263, 1.360
ADCS-ADL slope	−2.407	0.400	<0.0001	−3.190, −1.624
Intercept	−11.134	1.828	<0.0001	−14.717, −7.550

AD, Alzheimer's disease; ADAS–cog, AD Assessment Scale–Cognitive subscale; ADCS–ADL, AD Cooperative Study–Activities of Daily Living Scale; NPI, Neuropsychiatric Inventory; CI, confidence interval, SE, standard error.

Table 3.  Fit characteristics during development of the predictive equation.

Predictive factors included in the equation	AIC	R[2]
Time (log)	319.9	78.5%
Time (log) and static factors (ADAS–cog total score, ADCS-ADL total score, NPI hallucination score)	270.1	79.4%
Time (log), static factors (baseline total score of ADAS-cog, ADCS-ADL and NPI) and dynamic factors (ADAS–cog slope, ADCS–ADL slope)	163.2	88.2%

AD, Alzheimer's disease; ADAS–cog, AD Assessment Scale–Cognitive subscale; ADCS–ADL, AD Cooperative Study–Activities of Daily Living Scale; NPI, Neuropsychiatric Inventory; AIC, Akaike information criteria.

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