Table 2.
Unadjusted Association of Selected Diagnoses and Post-Operative Laboratory Tests during the Index Hospital Encounter with Infection During Re-Admission Stay (Frequency [Column %])
| Re-admission (30 d) | |||||
|---|---|---|---|---|---|
| Diagnosis or Laboratory Value | Total (N = 770) | No Infection (n = 481) | Infection (n = 289) | RR (95% CI) | pa |
| Diagnoses during the index admission | |||||
| Fluid and electrolyte disorders | 104 (13.5) | 54 (11.2) | 50 (17.3) | 1.34 (1.07–1.68) | 0.01 |
| Anemia | 157 (20.4) | 69 (14.4) | 88 (30.5) | 1.71 (1.43–2.04) | <0.0001 |
| Chronic kidney disease | 195 (25.3) | 107 (22.3) | 88 (30.5) | 1.29 (1.07–1.56) | 0.01 |
| Diabetes | 364 (47.3) | 208 (43.2) | 156 (54.0) | 1.31 (1.09–1.57) | 0.003 |
| Lower extremity ulcer | 179 (23.3) | 92 (19.1) | 87 (30.1) | 1.42 (1.18–1.72) | <0.001 |
| Thyroid disorders | 48 (6.2) | 22 (4.6) | 26 (9.0) | 1.49 (1.13–1.96) | 0.01 |
| End-stage renal disease | 91 (11.8) | 42 (8.7) | 49 (17.0) | 1.52 (1.23–1.89) | <0.001 |
| Infections during Index admission | |||||
| Any | 123 (16.0) | 52 (10.8) | 71 (24.6) | 1.71 (1.42–2.06) | <0.0001 |
| Cellulitis, abscess of leg or foot | 64 (8.3) | 27 (5.6) | 37 (12.8) | 1.62 (1.28–2.04) | <0.001 |
| Surgical site | 12 (1.6) | 7 (1.5) | 5 (1.7) | 1.11 (0.57–2.19) | 0.76 |
| Urinary tract | 21 (2.7) | 9 (1.9) | 12 (4.2) | 1.55 (1.05–2.26) | 0.06 |
| Pneumonia | 19 (2.5) | 9 (1.9) | 10 (3.5) | 1.42 (0.92–2.19) | 0.16 |
| Sepsis | 9 (1.2) | 3 (0.6) | 6 (2.1) | 1.79 (1.12–2.87) | 0.06 |
| Other | 41 (5.3) | 15 (3.1) | 26 (9.0) | 1.76 (1.37–2.26) | <0.001 |
| Other complications | |||||
| Hemorrhage/hematoma | 30 (3.9) | 12 (2.5) | 18 (6.2) | 1.64 (1.21–2.23) | <0.01 |
| Acute post-hemorrhagic anemia | 62 (8.1) | 26 (5.4) | 36 (12.5) | 1.62 (1.29–2.05) | <0.001 |
| Post-operative laboratory resultsb | |||||
| Hemoglobin (<8 g/dL) | 52 (7.9) | 14 (3.5) | 38 (14.5) | 1.98 (1.63–2.40) | <0.0001 |
| Glucose | |||||
| Low (<80 mg/dL) | 15 (2.3) | 9 (2.3) | 6 (2.3) | 1.00 (0.54–1.88) | 0.98 |
| Optimal (80–180 mg/dL) | 548 (83.3) | 343 (86.6) | 205 (78.2) | 0.72 (0.59–0.89) | 0.005 |
| High (>180 mg/dL) | 95 (14.4) | 44 (11.1) | 51 (19.5) | 1.43 (1.16–1.78) | 0.002 |
| BUN | |||||
| Low (males <8; females <6 mg/dL) | 17 (2.6) | 12 (3.0) | 5 (1.9) | 0.73 (0.35–1.54) | 0.37 |
| Normal (males 8–20; females 6–20 mg/dL) | 431 (65.5) | 279 (70.5) | 152 (58.0) | 0.73 (0.60–0.88) | 0.001 |
| High (>20 mg/dL) | 210 (31.9) | 105 (26.5) | 105 (40.1) | 1.43 (1.19–1.72) | 0.0003 |
| Potassium | |||||
| Low (<3.7 mEq/L) | 31 (4.7) | 25 (6.3) | 6 (2.3) | 0.47 (0.23–0.98) | 0.017 |
| Normal (3.7–5.2 mEq/L) | 591 (89.8) | 354 (89.4) | 237 (90.5) | 1.07 (0.78–1.49) | 0.65 |
| High (3.7–5.2 mEq/L) | 36 (5.5) | 17 (4.3) | 19 (7.3) | 1.35 (0.98–1.87) | 0.10 |
| Sodium | |||||
| Low (<135 mEq/L) | 73 (11.1) | 40 (10.1) | 33 (12.6) | 1.15 (0.88–1.52) | 0.31 |
| Normal (135–145 mEq/L) | 580 (88.2) | 355 (89.7) | 225 (85.9) | 0.82 (0.63–1.06) | 0.14 |
| High (>145 mEq/L) | 5 (0.8) | 1 (0.3) | 4 (1.5) | 2.02 (1.29–3.17) | 0.06 |
| Platelet count | |||||
| Low (<150 103/μL) | 73 (11.1) | 47 (11.9) | 26 (9.9) | 0.88 (0.64–1.22) | 0.43 |
| Normal (150–400 103/μL) | 539 (81.9) | 330 (83.3) | 209 (79.8) | 0.87 (0.69–1.09) | 0.24 |
| High (>400 103/μL) | 46 (7.0) | 19 (4.8) | 27 (10.3) | 1.53 (1.18–1.99) | 0.006 |
| White blood cell count | |||||
| Low (< 4.5 103/μL) | 6 (0.9) | 5 (1.3) | 1 (0.4) | 0.42 (0.07–2.50) | 0.24 |
| Normal (4.5–11.0 103/μL) | 474 (72.0) | 299 (75.5) | 175 (66.8) | 0.78 (0.64–0.95) | 0.01 |
| High (> 11.0 103/μL) | 178 (27.1) | 92 (23.2) | 86 (32.8) | 1.32 (1.09–1.60) | 0.006 |
a
Chi-square (t-test for continuous) comparison of having an infection during re-admission stay vs. no infection.
b
The 112 encounters with no post-operative laboratory data are excluded from the laboratory analyses.
CI = confidence interval; RR = relative risk.