Table 3.
Multivariable Log-Binomial Regression Model to Identify Variables Associated with Health Care–Associated Infections, Combined 2011 and 2015 Survey Populations.*
| Variable | Total No. of Patients | No. of Patients with Infection | Adjusted Risk Ratio (95% Cl) | P Value |
|---|---|---|---|---|
| Survey year 2015† | 12,299 | 394 | 0.84 (0.74–0.95) | 0.005 |
| Ventilator on the survey date‡ | 1,113 | 176 | 1.63 (1.38–1.92) | <0.001 |
| Central catheter on the survey date§ | 4,202 | 472 | 1.84 (1.59–2.13) | <0.001 |
| Urinary catheter on the survey date¶ | 4,958 | 312 | 1.24 (1.07–1.44) | 0.004 |
| Large hospital‖ | 4,909 | 280 | 1.20 (1.05–1.37) | 0.007 |
| Time from admission to survey | ||||
| ≤1 day | 7,022 | 27 | Reference | — |
| 2–4 days | 9,013 | 81 | 2.15 (1.41–3.38) | <0.001 |
| 5–6 days | 2,154 | 76 | 7.14 (4.67–11.26) | <0.001 |
| 7–9 days | 1,834 | 127 | 12.97 (8.71–20.05) | <0.001 |
| ≥10days | 3,557 | 535 | 25.45 (17.54–38.58) | <0.001 |
| Age** | ||||
| <40yr | 7,217 | 172 | Reference | — |
| 40–50 yr | 2,185 | 88 | 1.50 (1.17–1.89) | <0.001 |
| 51–57 yr | 2,277 | 114 | 1.67 (1.33–2.08) | <0.001 |
| 58–65 yr | 3,048 | 140 | 1.45 (1.17–1.78) | <0.001 |
| 66–72 yr | 2,703 | 104 | 1.39 (1.10–1.75) | 0.005 |
| 73–80 yr | 2,815 | 113 | 1.56 (1.24–1.95) | <0.001 |
| ≥81yr | 3,335 | 115 | 1.65 (1.31–2.07) | <0.001 |
The total number of patients who were included in either survey was 23,581. One patient from the 2011 survey for whom age was unknown was excluded from the model. Other variables that were tested but found not to be significant predictors of the risk of health care–associated infection were survey month (May or June vs. July through September) and location of the patient in a critical care unit (yes vs. no).
The comparator group for the risk ratio was the group of patients in the 2011 survey.
The comparator group for the risk ratio was the group of patients without a ventilator or for whom the presence of a ventilator was unknown. The presence of a ventilator was unknown for 36 patients without a health care–associated infection and for 1 with a health care–associated infection.
The comparator group for the risk ratio was the group of patients without a central catheter or for whom the presence of a central catheter was unknown. The presence of a central catheter was unknown for 62 patients without a health care–associated infection and for 2 with a health care–associated infection.
The comparator group for the risk ratio was the group of patients without a urinary catheter or for whom the presence of a urinary catheter was unknown. The presence of a urinary catheter was unknown for 65 patients without a health care–associated infection and for 5 with a health care–associated infection.
The comparator group for the risk ratio was the group of patients in small or medium hospitals.
The model excluded 1 patient without a health care–associated infection for whom age was unknown.