Table 2. Independent risk factors for unplanned readmission related to index surgery assessed by multivariable Cox proportional hazards model.
REF: reference group for comparison. CVA: cerebral vascular accident; SSI: surgical site infection.
| Independent risk factors for unplanned readmission (I): surgical procedure type, postoperative diagnosis, patient characteristics, medical profiles, preoperative labs | |||||
|---|---|---|---|---|---|
| Category | Variable | p value | Hazard Ratio (HR) | 95% HR Confidence Interval (low, high) | |
| Surgical procedure type | Anterior surgery only - 2–3 levels or fewer | (REF) | |||
| Anterior and posterior together | 0.010 | 1.8 | 1.1 | 2.7 | |
| Anterior surgery only - more than 3 levels | 0.057 | 1.4 | 1.0 | 1.9 | |
| Posterior only - up to 6 levels | 0.32 | 1.1 | 0.9 | 1.4 | |
| Posterior only - greater than 6 levels | 0.10 | 1.3 | 0.9 | 1.8 | |
| Diagnosis group | Cervical Spondylosis/Stenosis/Disc | (REF) | |||
| Solitary tumor (malignant or benign) | <0.001 | 3.0 | 1.8 | 4.8 | |
| Cervical Fractures/Dislocations | 0.026 | 1.9 | 1.1 | 3.5 | |
| Thoracolumbar Spondylosis/Stenosis/Disc | <0.001 | 1.7 | 1.3 | 2.1 | |
| Spondylolisthesis | 0.054 | 1.4 | 1.0 | 2.0 | |
| Disseminated tumor | 0.094 | 1.6 | 0.9 | 2.9 | |
| Thoracolumbar Fractures/Dislocations | 0.71 | 1.1 | 0.6 | 2.2 | |
| Spinal Fractures/Dislocations, Others, Unspecified | 0.37 | 1.3 | 0.7 | 2.4 | |
| Infection | 0.76 | 0.9 | 0.4 | 1.8 | |
| Scoliosis | 0.48 | 1.2 | 0.8 | 1.7 | |
| Other | 0.28 | 0.8 | 0.6 | 1.2 | |
| Age | 18–40 | 0.96 | 1.0 | 0.7 | 1.5 |
| 41–50 | (REF) | ||||
| 51–60 | 0.013 | 1.4 | 1.1 | 1.9 | |
| 61–70 | 0.006 | 1.5 | 1.1 | 2.0 | |
| > 70 | 0.002 | 1.6 | 1.2 | 2.2 | |
| History of severe COPD | Yes vs. No | <0.001 | 1.9 | 1.5 | 2.6 |
| ASA class | 1–2 (No/Mild Disturb) | (REF) | |||
| 3 (Severe Disturb) | <0.001 | 1.4 | 1.1 | 1.6 | |
| 4–5 (Life Threat/Moribund) | 0.016 | 1.6 | 1.1 | 2.2 | |
| Unknown | <0.001 | 5.2 | 2.1 | 12.8 | |
| Preoperative serum creatinine (mg/dL) | < 1.5 | (REF) | |||
| ≥ 1.5 | 0.040 | 1.5 | 1.0 | 2.3 | |
| Unknown | 0.88 | 1.1 | 0.5 | 2.2 | |
| Preoperative INR | < 1.5 | (REF) | |||
| ≥ 1.5 | 0.001 | 2.6 | 1.5 | 4.7 | |
| Unknown | 0.25 | 0.9 | 0.7 | 1.1 | |
| Currently on dialysis (preop) | Yes vs. No | 0.035 | 2.5 | 1.1 | 5.7 |
| Independent risk factors for unplanned readmission (II): major perioperative complications during or after index hospitalization as risk factors | |||||
|---|---|---|---|---|---|
| Category | Variable | p value | Hazard Ratio (HR) | 95% HR Confidence Interval (low, high) | |
| Deep/Organ Space SSI | Yes vs. No | <0.001 | 78.7 | 59.5 | 104.2 |
| Pulmonary Embolism | Yes vs. No | <0.001 | 10.0 | 6.6 | 15.1 |
| Acute renal failure | Yes vs. No | 0.001 | 6.8 | 2.1 | 22.2 |
| Stroke/CVA with neurological deficit | Yes vs. No | 0.015 | 2.8 | 1.2 | 6.2 |
| Risk factors that were also adjusted for, but were considered “non-significant” with the p value less than 0.05: | |||||
|---|---|---|---|---|---|
| Category | Variable | p value | Hazard Ratio (HR) | 95% HR Confidence Interval (low, high) | |
| Gender | Male vs. Female | 0.42 | 0.9 | 0.8 | 1.1 |
| Current smoker within one year | Yes vs. No | 0.95 | 1.0 | 0.8 | 1.2 |
| >10% loss body weight in last 6 months | Yes vs. No | 0.73 | 1.2 | 0.5 | 2.7 |
| Dyspnea | At rest/Moderate exertion vs. No | 0.99 | 1.0 | 0.8 | 1.3 |
| Congestive heart failure in 30 days before surgery | Yes vs. No | 0.93 | 1.0 | 0.4 | 2.6 |
| Hypertension requiring medication | Yes vs. No | 0.97 | 1.0 | 0.8 | 1.2 |
| Insulin-dependent Diabetes | Yes vs. No | 0.097 | 1.3 | 1.0 | 1.7 |
| Steroid use for chronic condition | Yes vs. No | 0.060 | 1.3 | 1.0 | 1.8 |
| Bleeding disorders | Yes vs. No | 0.58 | 1.2 | 0.7 | 1.9 |
| Preoperative serum sodium (mmol/L) | ≤ 130 | 0.89 | 1.0 | 0.5 | 2.1 |
| > 130 | (REF) | ||||
| Unknown | 0.99 | 1.0 | 0.5 | 1.9 | |
| Preoperative BUN (mg/dL) | ≤ 40 | (REF) | |||
| > 40 | 0.17 | 0.6 | 0.3 | 1.3 | |
| Unknown | 0.59 | 0.9 | 0.5 | 1.5 | |
| Preoperative WBC count (/mL) | < 12,000 | (REF) | |||
| ≥ 12,000 | 0.76 | 1.1 | 0.8 | 1.5 | |
| Unknown | 0.093 | 0.3 | 0.1 | 1.2 | |
| Preoperative hematocrit (%) | ≤ 24 | 0.93 | 1.0 | 0.4 | 2.7 |
| > 24 to ≤ 35 | (REF) | ||||
| > 35 | 0.91 | 1.0 | 0.8 | 1.3 | |
| Unknown | 0.85 | 0.9 | 0.3 | 2.8 | |
| Preoperative platelet count (/mL) | ≤ 50,000 | 0.15 | 2.3 | 0.7 | 7.4 |
| > 50,000 | (REF) | ||||
| Unknown | 0.11 | 2.5 | 0.8 | 7.6 | |
| Unplanned intubation | Yes vs. No | 0.86 | 0.9 | 0.5 | 1.8 |
| Cardiac arrest requiring CPR | Yes vs. No | 0.70 | 1.3 | 0.3 | 5.6 |
| Myocardial infarction | Yes vs. No | 0.094 | 2.2 | 0.9 | 5.5 |