Mortality measures

Mortality measures

18 March 2008

Mike Davidge

Mortality measures

What measure are we using?

• To track the progress of the campaign we are using Brian Jarman’s measure:

Hospital standardised mortality ratio

Mortality measures

Why use this?

• Why can’t we just track the number of deaths?

Mortality measures

What is HSMR?

• The HSMR is calculated as a ratio of the actual number of deaths to the expected number of deaths among patients in acute hospitals.

• An HSMR equal to 100 suggests that there is no difference between the hospital’s mortality rate and the overall average rate; greater than 100 suggests that the local mortality rate is higher than the overall average; and less than 100 suggests that the local mortality rate is lower than the overall average.

Mortality measures

Which patients in the original study?

• looked at four years of data, from1991-2 to 1994-5.

• excluded community and specialty institutions, small hospitals and hospitals without accident and emergency units.

• excluded any hospital that had poor quality data

• included discharge records only

• Included discharges if the primary diagnosis was one of 85 primary diagnoses which accounted for 80% of deaths.

• Excluded all transfers between hospitals (2% of admissions and 3% of discharges).

Mortality measures

Expected deaths

• Stratify national admissions according to:DiagnosisAge groupGenderType of admission (acute/ non acute)

• National mortality proportion (NMP) = deaths per admission in each group

• Expected deaths (Trust A) = NMP x Trust A admissions

Mortality measures

Who calculates

• We have an agreement that Dr Foster Intelligence will calculate the monthly HSMRs for us