The CHQC study, as presented in this issue, addressed the quality of
ICU care by assessing one main patient outcome, in-house mortality.
Although the authors’ assessment requires some knowledge of
statistical procedures often used in outcomes research, everyone
interested in the issue of quality of ICU care should learn something
new. The CHQC study compared hospital mortality across institutions. A
retrospective cohort design was used to compare actual to predicted
mortality after adjustment for severity of illness. A standardized
mortality ratio <1 (ie, actual mortality rates
significantly less than predicted) demonstrated superior care.
Conversely, a standardized mortality ratio (SMR) significantly >1
demonstrated a need for improvement. Most interestingly, the authors
discovered some trends with time. SMRs and variation in SMRs declined
from 1991 to 1995, which suggests a possible improvement in the quality
and consistency of care. However, mean hospital length of stay also
declined, whereas the number of discharged patients to skilled nursing
facilities increased. This decline in mortality was likely due to a
shift in patient care from the hospital to nursing home facilities,
rather than due to procedural improvements in the ICU. It is also
conceivable that some change may be attributed to the Hawthorne effect,
that is, behavior that is monitored may enhance performance. With time,
this may wane.