The APACHE II system classified patients on the basis of the severity of their disease, while the groups related with the diagnosis (DRG) are classified according to the consumption of resources. Nonetheless, the relative DRG weight (RWDRG) may be related with severity given that the most severe patients are also usually the most expensive. The aims of the study were: 1) verify the ability of DRG to measure clinical severity and 2) compare the prognostic value of both systems.
Methods: A transversal cut off was performed (316 consecutive admissions in intensive care units [ICU] with 23 exclusions due to unclear final evolution) with the patients being classified according to final hospital evolution in survivors and deaths. Each patient was given an APACHE II score corresponding to the first 24 hours in the ICU. Parallelly the cases were grouped in the corresponding DRG in accordance with the CIE-9-MC codification of their discharge report. The comparison of the means was carried out with the Student's t test, with the determination of prognostic values being performed by discriminant analysis.
Results: The survivors had an APACHE II score of 9.5 +/- 5.5 and the deaths of 22.5 +/- 7.8 (p < 0.0001). The RWDRG of the survivors was 1.4 +/- 0.9 and that of the deaths of 2.0 +/- 1.0 (p < 0.0001). On inclusion of all the patients the APACHE II prognostic value was 85.3% and the RWDRG 68.9% and both 84.6%. In the group of patients with a RWDRG lower than 1.6 the prognostic value of the APACHE II was of 87.6% and the RGRDW 72.0% and both 90%. In the group with RWDRG greater than 1.6 the prognostic value of the APACHE II was 85.1%, the RWDRG 73.0% and both 83.2%.
Conclusions: The system of the groups related with diagnosis indirectly measures clinical severity. APACHE II is significantly superior to the system of groups related with diagnosis with regard to prognostic value. The use of both systems together does not improve the prognostic value of APACHE II.