Table II. Univariate Cox Proportional Hazards Model for Primary Endpoint – Loss of Primary Patency.
These clinical characteristics were tested individually for their relationship to the occurrence of the primary endpoint over time. The preoperative IgM value, whether considered as the lowest quintile, quartile, or below the median, was significantly associated with loss of primary patency. The following factors were chosen for inclusion in the subsequent multivariate hazards model because they were significant, or approached significance: Leg status, Distal anastomosis, High risk vein graft, Minimum diameter, and lowest quartile of IgM value.
| Variable | Level | Hazard Ratio | Lower 95% | Upper 95% | P-value for Z statistic |
|---|---|---|---|---|---|
| Age | - | 1.04 | 0.98 | 1.11 | 0.22 |
| Leg Status (reference level = claudication) | Rest Pain | 1.81 | 0.40 | 8.13 | 0.44 |
| Ulceration | 3.20 | 0.96 | 10.67 | 0.06 | |
| Diabetes | Yes | 1.54 | 0.59 | 3.99 | 0.38 |
| Smoker | Yes | 1.03 | 0.39 | 2.71 | 0.96 |
| Distal Anastomosis (reference level = above knee) | Below knee | 1.94 | 0.43 | 8.73 | 0.39 |
| Tibial | 5.05 | 1.29 | 19.77 | 0.02 | |
| Prior Failed Graft | Yes | 2.22 | 0.70 | 7.00 | 0.18 |
| High Risk Vein Graft | Yes | 2.53 | 0.91 | 7.02 | 0.07 |
| Index Leg Ankle Brachial Index (for each .10 decrease) | - | 1.19 | 0.96 | 1.48 | 0.11 |
| Minimum Diameter | - | 0.23 | 0.10 | 0.56 | 0.001 |
| Pre-operative IgM value – Quintile | Lowest 20% | 3.37 | 1.15 | 9.87 | 0.03 |
| Pre-operative IgM value – Quartile | Lowest 25% | 3.53 | 1.30 | 9.58 | 0.01 |
| Pre-operative IgM value – Median | Below Median | 2.94 | 1.03 | 8.40 | 0.04 |