[Variations in Dutch National Medical Registration hardly affect the hospital standardised mortality rate (HSMR)].
OBJECTIVE
To analyse the variation in the registration of hospital admissions across Dutch hospitals and determine how this variation affects the Hospital Standardised Mortality Rate (HSMR).


METHODS
Retrospective, descriptive.


METHODS
We used data from the National Medical Registration (LMR), covering the records of all hospital admissions in 2005 in Dutch hospitals, to analyse the variation between hospitals in 3 variables: the number of secondary diagnoses, the percentage of unplanned admissions, and the percentage of non-specified diagnoses ('other diagnoses'). The impact of this variation on the HSMR was analysed by calculating the correlation between the HSMR and each of the variables. The correlation between the original HSMR and the HSMR without adjustment for these variables was also calculated.


RESULTS
The variation in the percentages of unplanned admissions and admissions with a non-specified diagnosis was low. The variation in these two variables had a small or no effect on the HSMR. There was a considerable variation in the mean number of secondary diagnoses per hospital. This variation had a limited but statistically significant effect on the HSMR. The HSMR calculated without adjustments for secondary diagnoses correlated strongly with the original HSMR.


CONCLUSIONS
This analysis does not support the view that the HSMR is strongly affected by variation in the registration of hospital admissions and is therefore not reliable. Therefore, there is no need for restraint with regard to publication of the Dutch HSMR.
Pieter
D Daniël
DD
Kiwa Prismant, Utrecht, the Netherlands. daniel.pieter@prismant.nl
Kool
R B Tijn
RB
Westert
G P Gert
GP
D002423:Cause of Death; D003953:Diagnosis-Related Groups; D019538:Health Care Surveys; D017052:Hospital Mortality; D006801:Humans; D009426:Netherlands; D010343:Patient Admission / Q000706:statistics & numerical data*; D010351:Patient Discharge / Q000706:statistics & numerical data*; D011785:Quality Assurance, Health Care; D012042:Registries; D012189:Retrospective Studies