Observed-to-expected mortality is calculated as:
Observed deaths ÷ Expected deaths
Therefore:
72 ÷ 90 = 0.80.
An O/E ratio of 0.80 means that observed mortality was lower than predicted by the applicable risk-adjustment model. Specifically, observed deaths were 20% below the expected number.
A ratio of 1.0 indicates observed mortality equals expected mortality. Values above 1.0 indicate more deaths than predicted, while values below 1.0 indicate fewer deaths than predicted.
CDI influences the integrity of mortality analysis because the documented disease burden contributes to clinical data used by many risk-adjustment methodologies. If significant comorbidities are incompletely documented, expected mortality may not fully reflect the patient's clinical risk.
However, mortality review must never become a mechanism for adding unsupported diagnoses. The objective is accurate clinical representation.
The CCDS candidate handbook explicitly identifies data analysis, reporting functions, medical-record review, and the impact of documentation on clinical and administrative outcomes as important CDI competencies.
CCDS Reference Topics: Mortality index; O/E ratio; risk adjustment; quality reporting; CDI analytics.
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