Table 2

Disorder of water balance over the course of the ICU stay and ICU mortality

Variate

Hazard ratio

95% confidence interval

P value

Bayes information criterion^a

Crude analysis

Hypernatremia

3.34

1.55 to 6.88

0.002

313.29

DDAVP use

8.23

3.24 to 19.52

<0.001

304.75

Adjusted for baseline risk of death

Hypernatremia

3.00

1.34 to 6.51

0.003

291.17

DDAVP use

5.48

2.13 to 13.21

<0.001

286.07

Adjusted for baseline risk of death and for each other

Hypernatremia

2.04

0.81 to 4.84

0.092

288.09

DDAVP use

3.88

1.40 to 10.33

0.005

Hypernatremia adjusted for baseline risk and stratified according to DDAVP use

Hypernatremia with DDAVP use

0.58

0.07 to 3.67

0.57

256.53

Hypernatremia without DDAVP use

4.20

1.62 to 10.17

0.004

Hazard ratio, 95% confidence intervals, and P values associated with hypernatremia and desmopressin acetate (DDAVP) use in the intensive care unit (ICU), estimated by six different Cox proportional-hazards regression models. Hazard ratios associated with hypernatremia and DDAVP use were first estimated in separate models, without adjusting for confounding factors (Crude analysis), and after adjusting for baseline risk (Adjusted for baseline risk of death). They were then estimated including hypernatremia and DDAVP use in the same model in order to isolate the effect of each variate independently of the other (Adjusted for baseline risk of death and for each other). Finally, the hazard ratio associated with hypernatremia was estimated stratifying the Cox regression model for DDAVP use (Hypernatremia adjusted for baseline risk and stratified according to DDAVP use). Baseline risk is represented by the score from the International Mission for Prognosis and Analysis CT prognostic model [11]. ^aA measure of both model fit and parsimony; the better the model, the smaller the associated BIC value.

Maggiore et al. Critical Care 2009 13:R110   doi:10.1186/cc7953