Objectives: To determine whether the 12 hour and 24 hour PRISM score predict risk of mortality in our PICU.
Design:Prospective analysis.
Setting:Level III tertiary PICU.
Materials & Methods:
PRISM score was calculated at 12 and 24 hours for patients admitted to PICU. Chi-square test, Hosmer Lemeshow goodness-of-fit test, t-test & ROC (receive operating charactistics) curves analysis was performed.
Results:
This study conducted over 15 months (October 2003 to December 2004) included 503 patients (298 males, 205 females). Systems affected: Infections 28.8%, Central nervous system-CNS 17.9%, Respiratory-RS 17.1%, Cardiovascular – CVS 14.1%, Miscellaneous 12.1%, and CVS + RS 9.9%. 118 patients (23.5%) died. Mean PRISM score at 12 and 24 hours was 6.50 (SD 6.943) and 4.17 SD 6.142). The 12 hours PRISM score was significantly lower than 24 hour score, but without any change in mortality. Mean 12 hour and 24 hour scores were highest for CNS (7.77 and 5.46) and least for RS (4.77 and 1.93), however the mortality did not differ significantly according to systems involved. Mortality as per various intervals for 12 hour PRISM score was – 0-9: 13.2% (50 cases), 10-19: 50% (48), 20-29: 61.9% (13) and> / = 30: 100% (7 cases). Mortality as per various intervals for 24 hour PRISM score was – 0-9: 16% (67 cases), 10-19: 53% (35), 20-29: 92.9% (13) and> / = 30: 100% (3 cases). Mortality was 23.4% (34 cases), 23.3% (21), 22.1% (19), 32.4% (23), 14.8% (9), & 24% (12) for infections, CNS, RS, CVS, Miscellaneous and CVS + RS respectively. Mean PRISM scores were significantly higher in patients who died. Observed mortality compared well with that predicted by Hosmer Lemeshow test. For each unit increase in the PRISM score the log odds of dying increased by 0..153 for 12 hours & 0.152 for 24 hour score. ROC curve analysis revealed AUC of 77.0% for 12 hour score and 70.09% for the 24 hour score (both acceptable).
Conclusions:
PRISM score at 12 hours and 24 hours can satisfactorily predict the mortality (irrespective of the system involved) in our PICU. Though the PRISM scores tend to decrease over time (12 vs 24 hour score), mortality does not change significantly. Mortality rises with rising PRISM score.
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