ICU mortality benchmarking with case-mix adjustment — FFICM MCQ

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ModerateQuality and EvidenceICU mortality benchmarking with case-mix adjustmentFFICM

An ICU has a crude mortality of 28% this year compared with 18% in a neighbouring unit. The case mix includes more emergency laparotomies, severe pancreatitis and inter-hospital transfers. The clinical director wants to know whether outcomes are unexpectedly poor and where to focus review. What is the most appropriate investigation?

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Correct answer: E — Review risk-adjusted mortality and diagnostic subgroup data through the audit dataset

The correct answer is E, review risk-adjusted mortality and diagnostic subgroup data through the audit dataset. Crude mortality is heavily confounded by case mix, and this unit has a disproportionate share of high-risk admissions (emergency laparotomies, severe pancreatitis, inter-hospital transfers), all of which carry independently higher expected mortality. The appropriate method is to calculate a standardised mortality ratio using a validated risk-prediction model (as in the ICNARC Case Mix Programme), comparing observed to expected deaths, and then to interrogate diagnostic subgroups to identify where any excess mortality genuinely lies. This converts a crude, uninterpretable percentage into a case-mix-adjusted comparison that can generate focused, actionable review questions rather than a misleading league-table figure. Why the other options are wrong: D. Compare crude mortality alone: this ignores case mix entirely and will systematically penalise units that accept sicker, more complex patients, producing a false signal of poor performance. A. Exclude deaths after treatment limitation: selectively removing these deaths distorts the denominator, hides potentially important end-of-life care processes from review, and is not part of validated risk-adjustment methodology. B. Rank consultants by unadjusted deaths: individual clinician mortality league tables without risk adjustment are statistically unreliable given small numbers and case-mix variation, and risk unfair blame rather than useful learning. C. Stop admitting high-risk patients: this is a service-level reaction based on unadjusted data and would deny appropriate critical care to patients who need it, without first establishing whether outcomes are actually worse than expected. Key point: always risk-adjust mortality (observed versus expected, standardised mortality ratio) and examine diagnostic subgroups before concluding that crude mortality differences reflect true quality-of-care problems.

Reference: ICNARC Case Mix Programme: Hospital mortality, risk-adjusted (ICNARC model), Online Reports, https://onlinereports.icnarc.org