Duration of CVC use was a major risk factor for CR‐BSI (OR 5‐9 days 4.3 and ≥ 10 days 8.4 vs. 1‐4 days). This is consistent with the results of other studies: a duration of a central vascular catheter longer than 7 days was associated with an up to 8.7 times increased risk for CR‐BSI [20]. Duration of urinary catheterization of 5 days or longer was a risk factor for urinary tract infection, which is in accordance with other findings [21]. These risk factors are of importance when stratifying nosocomial infection risks for interhospital comparison. Furthermore, some of them can be modified as to lower the infection risk. Several studies have reported that the duration of ventilation was successfully reduced without adverse patient outcomes [29‐31]. Although less complex to achieve and perhaps therefore not a subject of explicit study, the timely removal of central vascular catheters and urinary catheters is of great importance because reducing the device duration can also reduce these patients’ risk of developing an infection [32]. Mortality Nosocomial pneumonia is associated with a high crude mortality, ranging from 20% to 71% [13]. We found that VAP was associated with a relatively low crude mortality of 26%, not significantly different from that in ventilated patients without VAP. Crude mortality was significantly higher for patients with CR‐BSI and CA‐UTI. However, neither VAP, CR‐ BSI nor CA‐UTI was associated with mortality when adjusted for other risk factors. Some studies found VAP to be an independent risk factor for mortality while others did not [12;33‐35]. Some authors conclude this to be related to the used diagnostics. In recent studies CR‐BSI is not associated with a significant attributable mortality. Case‐control studies have found similar crude as well as adjusted mortality rates in patients with and without CR‐BSI [36‐38]. Laupland et al [18] studied ICU‐acquired UTI in a large cohort of ICU patients over 90% of whom had a urinary catheter and also found a comparable difference in crude mortality between patients with and without UTI. An ICU‐acquired UTI was, however, not an independent risk factor for death. In CA‐UTI this may be due to the fact that UTI can simply be a marker of other serious conditions [21]. There are very few other studies which include both nosocomial infection and duration of device use as risk factors for mortality. Increased duration of device use was an independent risk factor for mortality with ventilated patients and patients with a central line, but not in patients with a urinary catheter. In patients on a ventilator or with a CVC the duration of device use is related to the development of the patient’s condition at the ICU and therefore closely associated with mortality. Being in need for both ventilation and a CVC increased the mortality risk, compared with needing ventilation or a CVC only. For ventilation this association was stronger than that with APACHE II score determined within the first 24 h. When all 32 Chapter 2
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