Expected mortality

The expected mortality is an option of the quality of care report.

How is expected mortality calculated

Let's take two popular procedures

• “VSD repair, Patch” with 1.38% mortality
• “Arterial switch operation (ASO)” with 7.12% mortality

Let's imagine two hospitals: ABC and DEF:

• ABC performed “VSD repair, Patch” 100 times and didn't perform ASO (and no other procedures)
• DEF performed “VSD repair, Patch” 60 times and ASO 20 times (and no other procedures)

Since “VSD repair, Patch” has 1.38 mortality, you would expect that ABC's mortality will be 1.38% -- and that's how expected mortality is calculated. DEF will need a little more complex calculations.

• “VSD repair, Patch” was 75% of DEF's procedures
• “Arterial switch operation (ASO)” was 25% of DEF's procedures

The expected mortality of DEF will be:

<math>0.75 \times 1.38% + 0.25 \times 7.12% = 2.81%</math>

DEF's expected mortality is slightly higher because 25% of its procedures were the ASO procedures, which has a lot higher mortality than VSD patch.

If a hospital performed more procedures, there will be more things to add in the sum. The final formula is:

The formula

<math>E = \sum_{p \in P} \frac{N_p}{N} \times m_p </math>

Where:

• N stands for total number of patients
• P stands for a set of procedures (currently about 150)
• p stands for a single procedure (from P)
• N_p stands for number of patients who had procedure p
• m_p stands for mortality of procedure p
• E stands for the expected mortality