Over 12 months duration we recruited 980 consecutive patients that were eligible according to the inclusion criteria and signed an informed consent. Table 1 present patients' characteristics, according to their status of 30-day re-admission. The median age was 72 years (IQR 65–79) with 56.8% male patients. The following characteristics were found to be significantly different between patients who were re-admitted during 30 days after discharge and those who did not: Amongst re-admitted patients there was a longer length of hospital stay: median LOS 3 [IQR; 2.00, 5.00] vs. 2 days [IQR; 1.00, 4.00], p = 0.015. In addition, re-admitted patients were more likely to come from nursing homes: 7.6% vs. 2%, p = 0.004 (for the overall difference in outpatients' settings). Cirrhosis was also more prevalent amongst re-admitted patients (3.3% vs. 0.5%, p = 0.017). Laboratory parameters that were significantly different included lower hemoglobin concentration (11.8 g/dL vs. 12.8 g/dL, p < 0.001) and higher creatinine concentration (1.08 mg/dL vs. 0.96 mg/dL, p = 0.048) amongst patients with a 30-days re-admission. Patients' characteristics associated with sarcopenia and frailty that were found to be significantly different in patients with or without a 30-days re-admission event were a lower level of ALT blood activity (median 11 IU vs. 14 IU, p = 0.005) and a higher frail score (median 3 vs. 2.5, p < 0.001). MAMC values were not significantly different between these two groups of patients.
Table 1
Patients' characteristics according to 30-day readmission status.
| 30-day readmission status | |
| No (N = 888) | Yes (N = 92) | p |
LOS; days (median [IQR]) | 2.00 [1.00, 4.00] | 3.00 [2.00, 5.00] | 0.015 |
Patient demographics |
Female gender; N (%) | 380 (42.8) | 43 ( 46.7) | 0.537 |
Age (Years); (median [IQR]) | 72.00 [65.00, 79.00] | 74.00 [65.75, 79.50] | 0.344 |
BMI (median [IQR]) | 27.12 [24.30, 31.22] | 26.93 [23.51, 30.79] | 0.591 |
Norton score (median [IQR]) | 19.00 [17.00, 20.00] | 18.00 [17.00, 19.00] | 0.167 |
Married; N (%) | 573 (64.5) | 49 (53.3) | 0.14 |
Outpatient setting, before admission; N (%) | 0.005 |
Community | 833 (93.8) | 84 ( 91.3) |
Nursing home | 18 ( 2.0) | 7 ( 7.6) |
Long-term facility | 15 ( 1.7) | 1 ( 1.1) |
Background diagnoses; N (%) |
IHD; Ischemic heart disease | 303 (34.1) | 41 (44.6) | 0.060 |
CHF; Congestive heart failure | 75 ( 8.4) | 12 (13.0) | 0.199 |
Atrial fibrillation | 174 (19.6) | 25 (27.2) | 0.113 |
DM; Diabetes mellitus | 406 (45.7) | 52 (56.5) | 0.062 |
Hypoglycemia during hospitalization | 5 (0.8) | 1 (1.6) | 0.007 |
Status post stroke | 138 (15.5) | 18 (19.6) | 0.393 |
Dementia | 13 (1.5) | 0 (0.0) | 0.490 |
CRF; Chronic renal failure | 138 (15.5) | 14 ( 15.2) | 1.000 |
Chronic obstructive pulmonary disease | 174 (19.6) | 20 (21.7) | 0.723 |
Liver cirrhosis | 4 (0.5) | 3 (3.3) | 0.017 |
Solid malignancy | 106 (11.9) | 10 (10.9) | 0.895 |
Laboratory parameters (median [IQR]) |
HB; g/dL | 12.79 [11.39, 14.12] | 11.77 [10.46, 12.96] | < 0.001 |
CREAT; mg/dL | 0.96 [0.75, 1.29] | 1.08 [0.77, 1.66] | 0.048 |
Albumin; g/dL | 3.80 [3.50, 4.10] | 3.80 [3.50, 4.00] | 0.198 |
Frailty Parameters |
ALT; (IU; median [IQR]) | 14.00 [10.00, 18.00] | 11.00 [9.00, 15.50] | 0.005 |
FRAIL questionnaire score (median [IQR]) | 2.50 [1.00, 3.00] | 3.00 [2.00, 4.00] | < 0.001 |
MAMC percentile (median [IQR]) | 87.50 [58.80, 98.00] | 86.05 [53.57, 98.00] | 0.536 |
LOS, Length of stay; BMI, Body mass index; MAMC, Mid-are muscle circumference |
Table 2
Cohort according to LOS (patients whose LOS ≥ 14 days excluded).
| Length of hospital stay ≥ 3 days | p |
| No (N = 504) | Yes (N = 456) | |
30-day readmission | 38 (7.5) | 56 (12.3) | 0.018 |
Patient demographics |
Female gender; N (%) | 216 (42.9) | 199 (43.6) | 0.858 |
Age (Years); (median [IQR]) | 71.00 [64.00, 78.00] | 73.00 [65.00, 80.00] | 0.005 |
BMI (median [IQR]) | 27.16 [24.55, 31.20] | 27.06 [23.95, 31.22] | 0.648 |
Norton score (median [IQR]) | 19.00 [18.00, 20.00] | 18.00 [15.00, 19.00] | < 0.001 |
Married; N (%) | 337 (66.9) | 275 (60.3) | 0.041 |
Outpatient setting, before admission; N (%) | 0.027 |
Community | 486 (96.4) | 419 (91.9) |
Nursing home | 8 (1.6) | 16 (3.5) |
Long-term facility | 4 (0.8) | 8 (1.8) |
Background diagnoses; N (%) |
IHD; Ischemic heart disease | 167 (33.1) | 173 (37.9) | 0.137 |
CHF; Congestive heart failure | 42 (8.3) | 44 (9.6) | 0.549 |
Atrial fibrillation | 96 (19.0) | 101 (22.1) | 0.268 |
DM; Diabetes mellitus | 223 (44.2) | 223 (48.9) | 0.168 |
Hypoglycemia during hospitalization | 2 (0.5) | 4 (1.3) | 0.503 |
Status post stroke | 78 (15.5) | 77 (16.9) | 0.614 |
Dementia | 10 (2.0) | 3 (0.7) | 0.135 |
CRF; Chronic renal failure | 67 (13.3) | 81 (17.8) | 0.068 |
Chronic obstructive pulmonary disease | 92 (18.3) | 98 (21.5) | 0.240 |
Liver cirrhosis | 4 (0.8) | 3 (0.7) | 1.000 |
Solid malignancy | 56 (11.1) | 57 (12.5) | 0.571 |
Laboratory parameters (median [IQR]) |
HB; g/dL | 13.08 [11.85, 14.33] | 12.23 [10.74, 13.63] | < 0.001 |
CREAT; mg/dL | 0.92 [0.73, 1.15] | 1.04 [0.79, 1.54] | < 0.001 |
Albumin; g/dL | 3.90 [3.70, 4.20] | 3.70 [3.30, 4.00] | < 0.001 |
Frailty Parameters |
ALT; (median [IQR]) | 14.00 [10.00, 19.00] | 12.00 [9.00, 17.00] | < 0.001 |
FRAIL questionnaire (FQ) total score | 2.00 [1.00, 3.00] | 3.00 [2.00, 4.00] | < 0.001 |
MAMC percentile (median [IQR]) | 28.22 [25.84, 30.25] | 27.70 [25.48, 29.90] | 0.148 |
MAMC, Mid-are muscle circumference |
Table two present patients' characteristics according to the length of hospital stay. After we excluded patients hospitalized for more than 14 days (many of whom had socio-economic rather than medical barriers for discharge), amongst patients who had a longer LOS (over 3 days duration), several characteristics were significantly different: These patients were older (median age 73 vs. 71, p = 0.008), their 30-day re-admission rates were higher (12.2% vs. 7.5%, p = 0.019), they had lower Norton and Morse scores (18 vs. 19, p < 0.001 and 7 vs. 6, p = 0.001, respectively) and a lower proportion were married (59.9% vs. 66.9%, p = 0.027). Laboratory parameters were also significantly different between these patients groups: patients with longer hospital stay had lower hemoglobin concentration (12.2 g/dL vs. 13.1 g/dL, p < 0.001), higher creatinine concentrations (1.05 mg/dL vs. 0.92 mg/dL, p < 0.001), higher urea concentration (48 mg/dL vs. 41 mg/dL, p < 0.001), lower albumin concentration (3.7 g/dL vs. 3.9 g/dL, p < 0.001) and higher CRP concentration (26.3 mg/L vs. 7.2 mg/L, p < 0.001). Patients' characteristics associated with sarcopenia and frailty that were found to be significantly different in patients with longer hospitalizations were lower level of ALT (median 12 IU vs. 14 IU, p < 0.001) and higher FRAIL score (median 3 vs. 2, p < 0.001). MAMC values were not significantly different between these two groups of patients.
Two of the measures for sarcopenia and frailty used in this study: ALT activity measurement in the peripheral blood the FRAIL questionnaire, were not only found to be associated with higher risks for longer hospitalization and 30-days re-admission but were also found to be in correlation with each other. As presented in Table 3 and Fig. 3, both ALT and Frailty Score (FS) had statistically significant correlation with each other and with the MAMC measurements, although, the later was not associated with clinical outcomes. Figure 1 show a survival curve for 30-days readmission events according to FRAIL questionnaire classes (p = 0.0019) and Fig. 2 show a survival curve for 30-days readmission events according to ALT activity lower than 12 IU (p < 0.0001).
Table 3
Associations between different sarcopenia and frailty indices.
| N | ALT < 12 IU | N | ALT ≥ 12 IU | p |
Frail score (median (IQR)) | 411 | 3 (2.0–4.0) | 227 | 2 (1.0–3.0) | < 0.001 |
MAMC (median (IQR)) | 411 | 26.81 [24.84, 29.47] | 227 | 28.31 [26.12, 30.59] | < 0.001 |
| N | Frail score 3–5 | N | Frail score 0–2 | p |
ALT (median (IQR)) | 322 | 15.00 [11.00, 19.00] | 316 | 11.50 [9.00, 17.00] | < 0.001 |
MAMC (median (IQR)) | 506 | 28.15 [25.84, 30.62] | 474 | 27.72 [25.41, 29.81] | 0.04 |
In the adjusted model for 30-day readmission, ALT activity levels under 12 IU and a FRAIL score of 3 or greater were predictive for 30-day readmission (HR 2.06 [95% CI 1.34–3.16] and HR 1.59 [95% CI 1.02–2.48], respectively).
In a multivariate model for prolonged hospital stay (3–14 days), lower ALT levels and a higher FRAIL score were the only significant predictive factors (HR 1.33 [95% CI 1.00–1.76] and HR 1.55 [95%CI 1.18–2.04], respectively).
In a subgroup analysis described in Fig. 4, a lower ALT was significantly associated with 30-day readmission across most subgroups, except for a higher serum albumin level defined as > 3.5 g/dl (n = 250, HR 1.8 [95% CI 0.84–3.90]), with no significant interactions between ALT levels and the various stratifying variables.