Table 3.
Forced (All Covariates Entered) Logistic Regression Model to Predict 30-Day Post-Operative Status after Type A Acute Aortic Dissection among 121 Patients Operated, Between 2001 and Early 2007, at the University of Rome “La Sapienza”, Cardiac Surgical Department
| Covariates | Mean ±SD | F | Coeff | SE | t | p= | OR | ±95%CI |
|---|---|---|---|---|---|---|---|---|
| Demographic | ||||||||
| Year of surgery | 2004±2 | * | -0.1016 | 0.1976 | -0.51 | 0.6071 | 0.90 | 0.61-1.33 |
| Age (years) | 63±11 | 0.0141 | 0.0313 | 0.45 | 0.6527 | 1.01 | 0.95-1.08 | |
| Sex (0=female; 1=male) | 0.67 | -0.4593 | 0.6420 | -0.71 | 0.4743 | 0.63 | 0.18-2.22 | |
| Pre-operative | ||||||||
| High blood pressure | 0.82 | -0.3895 | 0.8409 | -0.46 | 0.6432 | 0.67 | 0.13-3.52 | |
| Marfan syndrome | 0.03 | ** | -15.9883 | 975.2700 | -0.00 | 0.9869 | 0.00 | 0.00-0.00 |
| Shock | 0.15 | ** | 0.7515 | 0.9802 | 0.77 | 0.4433 | 2.12 | 0.31-14.47 |
| Intubated | 0.14 | 1.4199 | 1.0819 | 1.31 | 0.1894 | 4.13 | 0.50-34.48 | |
| Neurological symptoms | 0.14 | ** | -3.1865 | 1.7932 | -1.78 | 0.0756 | 0.04 | 0.00-1.39 |
| Previous cardiac surgery | 0.03 | 3.1338 | 1.3942 | 2.45 | 0.0246 | 22.96 | 1.49-352.95 | |
| Operative | ||||||||
| Extracorporeal circulation (min) | 211±81 | 0.0034 | 0.0032 | 1.06 | 0.2889 | 1.01 | 1.00-1.01 | |
| Circulatory arrest (min) | 53±34 | *** | 0.0078 | 0.0092 | 0.85 | 0.3965 | 1.01 | 0.99-1.03 |
| Brain protection (coded)a | 1.45±0.60 | ** | 1.0478 | 0.5210 | 2.01 | 0.0443 | 2.85 | 1.02-7.92 |
| Bicuspid aortic valve | 0.03 | -0.7811 | 1.7660 | -0.44 | 0.6583 | 0.46 | 0.01-14.59 | |
| Hemopericardium | 0.24 | *** | 0.7868 | 0.6535 | 1.20 | 0.2286 | 2.20 | 0.61-7.90 |
| Type of surgery (coded)b | 2.46±1.62 | *** | 0.0203 | 0.2025 | 0.10 | 0.9203 | 1.02 | 0.69-1.52 |
| Immediate Post-operative | ||||||||
| Bleeding in the first 24 hours (ml) | 1022±986 | * | 0.0000 | 0.0002 | 0.00 | 0.9871 | 1.00 | 0.99-1.00 |
| Limb ischemia | 0.14 | ** | -0.9928 | 1.1412 | -0.87 | 0.3843 | 0.37 | 0.04-3.47 |
| Renal complications | 0.26 | -16.3139 | 809.7974 | -0.02 | 0.9839 | 0.00 | 0.00-0.00 | |
| Dialysis in continuous | 0.25 | ** | 15.9259 | 809.7979 | 0.02 | 0.9843 | 0.00 | 0.00-0.00 |
| Chronic renal failure | 0.07 | 4.1363 | 1.5620 | 2.65 | 0.0080 | 62.57 | 2.93-1336.62 | |
| Enterological complications | 0.05 | 0.9715 | 1.6152 | 0.60 | 0.5475 | 2.64 | 0.11-62.63 | |
| Neurological deficits | 0.31 | ** | -0.0429 | 0.4881 | -0.09 | 0.9299 | 0.96 | 0.37-2.49 |
| Constant | 199.1009 | |||||||
Table 3. There were 120 patients with data complete for all 22 covariates considered and 33 were 30-day deaths (27.5%). The forced logistic model classified correctly 57.58% of patients who died and 91.95% of survivors (82.5% of overall cases were thus correctly classified) with a global chi-square equal to 50.56 (p<0.0005).
Only proportions are given when data are discrete. In case of continuous and coded covariates, summary statistics are given as mean±standard deviation (SD).
: codes are 1 = retrograde; 2 = anterograde; 3 = anterograde and retrograde.
: codes are 1 = ascending aorta; 2 = ascending aorta plus hemiarch; 3 = ascending aorta plus arch; 4 = ascending aorta plus aortic valve; or surgery according to: 5 = Bentall; 6 = Cabrol.
F= analysis of variance compared to data from Table 4:
:p<0.05;
:p<0.01;
:p<0.001; Coeff: logistic regression coefficient; SE= standard error; A value of t (coeff/SE) t>|1.96| was considered statistically significant (p<0.05). OR = odds ratio ± 95%CI (lower and upper 95% confidence limits).