[ICU performance: results of a French study involving 80,000 ICU stays].

OBJECTIVE

The Standard Mortality Ratio (SMR), comparing the observed in-hospital mortality to the predicted, may measure the intensive care units (ICU) performance.

STUDY DESIGN

Multicentric retrospective national study.

METHODS

A probability model using a severity score such SAPS II calculated the predicted mortality rate. A national French study has been undertaken to compare the SMR of ICUs and looked for explanation.

RESULTS

One hundred six units, 34 were medical (32%), 18 surgical (17%) and 57 medical/surgical (51%) participated to the study. Forty-six ICUs (43%) were located in teaching hospitals. The SMR of the 87,099 stays was 0.84 (0.82-0.85). The SMR of ICUs varied from 0.41 to 1.55. Ten units had a SMR>0.85, which suggested a low performance. They had more stays for cardiovascular failures, as compared with others. The best units (SMR<0.82) had more stays for drug overdose. The SMR increased with the number of organ failures, from 0.47 with zero failure to 1.11 with 4 or more organ failures. The stays with cardiovascular failure, either unique or associated, had a higher SMR. The 7935 stays with a drug overdose had a SMR of 0.12 (0.10-0.14), which suggested a bad calibration of the model in theses cases.

CONCLUSION

The case mix must be taken in account when comparing the ICUs performance by the mean of SMR, particularly when the units admitted a lot of drug overdoses.