Even in the best hospitals, some patients will experience
complications either after an operation or as a result of
other care. This section of the report shows how well
each hospital is providing safe patient care by examining the
number of inpatient medical errors or “adverse events” that
could have been avoided. These “adverse events” are serious complications caused by medical treatment or medical advice and are called Patient Safety Indicators (PSIs).
PSIs were developed at the national level by the Agency for
Healthcare Research and Quality (AHRQ) after years of
research and analysis. AHRQ developed the PSIs to help
hospitals identify serious medical errors. When an adverse
event is identified, hospitals can put corrective systems in place
to prevent the error from recurring. The Centers for Medicare
and Medicaid Services (CMS) lists some of these errors as “never events.”
In 2009, the New Jersey legislature enacted the Patient Safety
Act, Public Law 2009, c.122 (S2471), requiring that the
Department include hospital-specific data on patient safety
performance and serious medical errors in the annual New
Jersey Hospital Performance Report. Evidence shows that
most of the adverse events classified as a PSI are
potentially preventable. This section of the report focuses on
the 12 PSIs mandated for public reporting.
PSIs differ from the way the recommended care measures are
calculated. Unlike the recommended care measures, a lower
rate in PSIs indicates better performance by a hospital. With
PSIs, lower rates mean fewer medical errors/adverse
events. In addition, the numbers on the PSI tables are not scores or simple percentages, as used with
the recommended care measures; they are rates.
How is the data collected?
The data comes from the New
Jersey hospital discharge database
also known as the Uniform Bill
(UB) data. Hospitals submit these
data to the State. The data used for
this analysis are from 2010.
The PSIs tables show
the rates of adverse events in each of
the 72 licensed hospitals in New
Jersey. Each PSI value shows the
extent to which patients experienced a
particular problem during their
hospital stay. The resulting rate is
expressed as the number of
complications or medical errors per
1,000 eligible hospital discharges.
For example, if a hospital with
1,000 obstetric patients who had
vaginal delivery without the
assistance of an instrument had 43
of these patients experience trauma
during delivery, the rate of
occurrence at this hospital would
be 43 per every 1,000 patients.
The PSIs rates in this report were
calculated by applying the AHRQ
PSI Software (Version 4.2) to the
2010 hospital discharge (UB) data.
The software is known for its
strength in the risk-adjustment
methodology. It calculates the
rates by comparing the number of
complications (adverse events)
expected in a particular hospital,
and how many patients actually
experienced the adverse events.
Hospitals that treat sicker or older
patients may be unfairly compared
to other hospitals with healthier
patients. Performing a “risk
adjustment” removes the
differences and allows all hospitals
to be compared fairly. Seven of the
12 PSIs rates presented in this
report are risk-adjusted. "Risk adjustment"
is a statistical method
that takes into account different
patient characteristics (e.g. age,
sex, comorbidities, severity of
illness, etc.) while calculating a
rate.
For example, if a patient has a preexisting
chronic illness before
entering the hospital, this condition
may increase the likelihood or risk
of that patient acquiring a
complication and perhaps not
surviving the procedure or
treatment. Advanced age is another
example that may increase the risk
of experiencing complications.
Starting in 2008, hospitals were
required to report data on Present
on Admission (POA) for each
patient on their UB forms. Patients
may have other illnesses and
conditions (comorbidities) upon
admission in addition to the health
problem for which they were
admitted.
It is often difficult to distinguish
these comorbidities from new health
problems acquired during
hospitalization. The POA indicator
identifies these pre-existing
conditions and those that occur
during the hospital stay. This way,
patients with the POA flag can be
excluded from the rate calculation, when appropriate, so that
performance comparison remains
fair and balanced.
A technical report containing
additional details such as the total
number of hospital discharges,
observed and expected adverse
event rates and the 95% confidence
intervals for the risk-adjusted rates
(when applicable), is available at
www.nj.gov/health/hpr.
A footnote at the top
of the table describes the PSI rates as "better
than statewide average” and “worse
than statewide average.” These
labels help identify hospitals that
have better than average, average,
or worse than average performances
compared to the statewide performance,
which is shown on the
top row of the table and called
“Statewide Rate.”
The National Rate is also provided
to give another comparison point.
Keep in mind that the National
Rate is from the previous year
(2008).
When a hospital’s rate is statistically
significantly above the
statewide rate, the hospital’s performance
is worse than average,
meaning more adverse events than
the average NJ hospital rate.
When a hospital’s rate is statistically
significantly below the
statewide average, the hospital’s
performance is better than average,
meaning fewer adverse events than
the average NJ hospital rate.
When a hospital’s result is not statistically
significantly different from
the statewide average, its performance
is the same as or similar to the
statewide rate.
Confidence Intervals are used to
identify those hospitals that have
statistically significantly higher or
lower complication rates than
expected after adjusting for the risk
factors of their patients. A hospital’s
rate is statistically significantly above
the statewide rate if its 95% confidence
interval falls completely above
the statewide rate.
By comparison, a hospital’s rate is
significantly below the statewide rate
if its 95% confidence interval falls
completely below the statewide rate.
This information is not included in
the table but can be
found in the technical report at
www.nj.gov/health/hpr.
Some rates that appear large are not
marked as statistically significantly
higher than the statewide rate, while
others that appear small are not
marked as statistically lower than
the statewide rate. The reason may
be that rates calculated from a small
number of events tend to have
wider confidence intervals that make
the statewide rate fall within the
interval, giving the appearance of
good performance by that hospital
compared to a hospital whose rates
are based on large numbers of
events.
Remember: Lower rates are better and mean the hospital has fewer
adverse events than the statewide
average rate.
Can I use PSIs to draw conclusions about patient safety in NJ hospitals?
PSIs are not intended as definitive
quality measures. However, the
PSI measures indicate differences
in hospital performance. They
measure differences in the hospitals’
ability to reduce severe and
potentially preventable complications
and adverse events.
Performance on a single PSI cannot
reliably indicate actual quality differences
among hospitals. Examining
the results of all the 12 PSIs together
will produce a more complete picture
of overall quality of care.
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