TABLE 2.
Univariate and multivariate Cox proportional hazards models for laboratory transport time for 4,322 blood cultures
| Factor | Univariate modela | Overall P | Multivariate modela | Overall P |
|---|---|---|---|---|
| Age | 0.001 | |||
| ≤50 yr | 1 | |||
| >50 yr | 1.11 (1.04-1.18) | |||
| Walking distance (two-way) | <0.001 | <0.001 | ||
| Within 4 min | 1 | 1 | ||
| Between 4 and 8 min | 0.51 (0.48-0.55) | 0.80 (0.69-0.84)c | ||
| Off-site wardsb | 0.30 (0.28-0.33) | 0.26 (0.15-0.45) | ||
| No. of daily rounds | <0.001 | <0.001 | ||
| None/off-site | 0.38 (0.35-0.42) | 0.64 (0.39-1.05) | ||
| One | 0.65 (0.60-0.70) | 0.85 (0.75-0.97) | ||
| Two | 1 | 1 | ||
| Three | 0.71 (0.64-0.78) | 0.40 (0.28-0.56) | ||
| Time of specimen collection before daily rounds | <0.001 | |||
| <0.5 h | 1 | |||
| 0.5-2 h | 1.16 (1.01-1.34) | |||
| 2-4 h | 1.00 (0.86-1.18) | |||
| 4-8 h | 0.96 (0.83-1.11) | |||
| >8 h | 0.84 (0.75-0.94) | |||
| Not applicable (off-site or no daily rounds) | 0.44 (0.39-0.50) | |||
| Collection during laboratory's open hours (7:30 a.m.-4:30 p.m.) | 1.24 | |||
| Yes | 1 | |||
| No | 0.95 (0.90-1.01) | |||
| Collection day | <0.001 | 0.017 | ||
| Weekdays | 1 | 1 | ||
| Weekend days | 0.87 (0.81-0.94) | 0.92 (0.85-0.98) | ||
| Medical specialty | <0.001 | <0.001 | ||
| Surgery | 1 | 1 | ||
| Thorax centerd | 0.74 (0.63-0.88) | 0.80 (0.65-0.98) | ||
| General internal medicine | 0.94 (0.77-1.14) | 0.90 (0.72-1.14) | ||
| Hematology/oncology | 0.34 (0.30-0.38) | 1.37 (1.04-1.80) | ||
| Gastroenterology | 1.05 (0.88-1.25) | 0.87 (0.72-1.05) | ||
| Nephrology | 0.98 (0.83-1.16) | 0.81 (0.68-0.97) | ||
| Infectious disease | 0.84 (0.72-0.98) | 0.69 (0.58-0.81) | ||
| Pulmonology | 0.47 (0.35-0.64) | 0.56 (0.41-0.78) | ||
| Neurology | 1.24 (0.95-1.61) | 1.16 (0.88-1.53) | ||
| ICU | 0.48 (0.42-0.54) | 0.52 (0.45-0.60) | ||
| Thorax center ICUd | 0.54 (0.46-0.63) | 0.55 (0.44-0.68) | ||
| ER | 0.26 (0.22-0.30) | 0.30 (0.25-0.36) | ||
| Other (outpatient, psychiatry, and revalidation) | 0.85 (0.67-1.10) | 1.48 (1.08-2.04) | ||
| Bacterial growth | 0.18 | |||
| No growth | 1 | |||
| Staphylococcus aureus | 1.07 (0.84-1.38) | |||
| Coagulase-negative staphylococcus | 0.83 (0.71-0.98) | |||
| Streptococcus and Enterococcus spp. | 0.89 (0.58-1.36) | |||
| Enterobacteriaceae | 0.86 (0.72-1.04) | |||
| Nonfermenter | 0.82 (0.55-1.23) | |||
| Yeast | 1.11 (0.69-1.78) | |||
| 2 or more different organisms | 1.30 (0.89-1.90) | |||
| Other | 1.15 (0.78-1.69) |
a
Data are shown as HR (95% CI). A variable with a HR smaller than one is associated with a longer transport time, while a variable with a HR larger than one is associated with a shorter transport time.
b
Off-site ward data pertain to specimens transported by courier service.
c
The difference between 4 and 8 min and off-site wards is significant.
d
Combined departments of wards and thoracic surgery, located in a separate building but connected with the main hospital building.