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Osmolar gap as an individual prognostic factor (revised data)


The assessment of the validity of the osmolar gap (OG) as an independent prognostic factor for the mortality of the newly admitted patients compared with the SAPS II and APACHE II scores.


All the newly admitted patients in two 12 (6 + 6)-bed ICUs regardless of the cause of admission.


Measurement of the freezing point and simultaneous calculation (using the known formula) of plasma osmolarity in every patient at the time of admission. Patient data and the overall outcome at 28 days were documented.


See Table 1. The findings were statistically analysed using a paired t test and a statistically significant difference was obtained (P < 0.001 for SAPS II and OG scores, and P < 0.000 for APACHE II and OG scores, respectively). In addition ROC analysis disclosed for OG an area under the curve of 0.745 ± 0.040 (SE).

Table 1


The OG appears to have good correlation with the existing clinical scoring systems and therefore it might be used as an independent prognostic factor. To find out the appropriate cutoff point for the OG obviously requires a greater number of patients in the present study, which is still underway.

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Aloizos, S., Liapis, G., Evodia, E. et al. Osmolar gap as an individual prognostic factor (revised data). Crit Care 10 (Suppl 1), P204 (2006).

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