An outlier is identified when an ICU’s SMR falls outside of the ‘funnel plot’ for their classification, where control limits are drawn using 95% and 99% confidence intervals around the mean SMR of the group. An ICU is only considered an outlier if it’s annual SMR falls above the upper outer control limit (99% confidence interval).
A structured process of analysis and reporting is undertaken to identify data quality and case mix issues that may explain the findings. An Outlier Working Group (OWG) provides the clinical and statistical oversight of the review process for the APD as does the ANZPIC Registry Clinical Advisory Committee (ARCAC) for the ANZPIC Registry.