Table 2.

Risk factors for time to unplanned re-admission to the hospital within 30 days following admission to the Department of Rehabilitation and Aged Care (DRAC).^a

Variable	Hazard Ratio	95% CI	P value
Age	1.00	0.96–1.03	.93
CIRS severity index
1.46 to 1.84	0.98	0.45–1.89	.838
≥ 1.85	1.50	0.69–3.28	.300
Albumin, mg/dl	0.64	0.38–1.05	.082
Number of drugs at DRAC admission
<4 drugs	Ref.
4 to 6 drugs	1.59	0.64–3.94	.315
≥ 7 drugs	3.94	1.62–9.54	.002
Delta Barthel Index at rehabilitation admissionb
≤ 24	Ref
25–56	1.48	0.79–2.75	.216
>56	2.67	1.35–5.27	.005
Delirium at DRAC admission	0.77	0.40–1.46	.421
MMSE scorec at DRAC admission	0.97	0.94–1.01	.128
Length of stay in the acute hospital
≤ 6 days	Ref.
7–13 days	1.74	0.93–3.25	.080
>13 days	2.67	1.39–5.10	.003

^aA multivariable Cox proportional regression model was used to identify the effect of risk factors evaluated at the time of DRAC admission on the time to unplanned readmission to the acute hospital within a 30-day follow-up. All the risk factors were first entered in the model as continuous variables, except for delirium at DRAC admission. The variables found to be statistically associated with a higher risk of hospital re-admission (p<0.05) were then categorized in tertiles, according to their distribution, to provide clinicians with actionable thresholds that could be applied in daily practice.

^bDelta Barthel index was calculated as the difference of Barthel Index pre-admission (i.e., Barthel index a month before the index acute hospital admission) and the Barthel Index at rehabilitation admission.

^cMini Mental State Examination, MMSE