Importance of publishing mortality rates: Mortality rates for certain inter
ventions or disease states have been used over the last decade as indicator
s of the quality of care provided by a given hospital, unit or, medical tea
m. If published, these rates would be a useful tool for decision makers in
the process of fund allocations, for public information, and for promoting
improved care in hospitals or units with a low classification.
Methodological limitations: It is difficult to adjust an indicator of morta
lity to disease-related risk factors and any modification of this adjustmen
t can have major consequences on the validity of subsequent comparisons. Th
e differences in mortality observed between hospitals and physicians can re
flect not only differences in quality of care but also differences in appro
aches to disease-related risk factors, therapeutic choices, or coding pract
ices. The lack of statistical power is a major limiting factor in interpret
ing differences in mortality rates. To evidence a statistically significant
difference in mortality between two hospitals whose rates are respectively
0.5% and 1% (for example in total hip replacement patients), it would be n
ecessary to include 4673 patients, a number which would correspond to 20 ye
ars data for a hospital performing 230 interventions per year. Consequently
, the number of interventions performed in the most active hospitals would
not be sufficient to make such comparisons.
Limitations and counter effects: Some studies have demonstrated that the pu
blication of mortality rates does not have a major influence on patients' d
ecisions nor on physicians' choice of a referral hospital. It would have no
effect on improving health care quality of the institutions cited. One the
contrary, certain counter effects have been observed: modification in pati
ent recruitment, higher-risk patients being referred to hospitals with unpu
blished mortality rates. For many authors, procedure indicators are more pe
rtinent than outcome indicators for detecting differences in health care qu
ality between different care structures.