Objective: Classifications of diagnoses and procedures are very important f
or the economical as well as the quality assessment of surgical departments
. They should reflect the morbidity of the patients treated and the work do
ne. The authors investigated the fulfillment of these requirements by ICD-9
(International Classification of Diseases: 9th Revision) and OPS-301, a Ge
rman adaptation of the ICPM (International Classification of Procedures in
Medicine), in clinical practice.
Design: A retrospective study was conducted using the data warehouse of the
Surgical Center II at the Medical Faculty in Essen, Germany. The sample in
cluded 28,293 operations from the departments of general surgery, neurosurg
ery, and trauma surgery. Distribution of cases per ICD-9 and OPS-301 codes,
aggregation through the digits of the codes, and concordance between the c
lassifications were used as measurements. Median and range were calculated
as distribution parameters. The concentration of cases per code was graphed
using Lorenz curves. The most frequent codes of diagnoses were compared wi
th the most frequent codes of surgical procedures concerning their medical
information.
Results: The total number of codes used from ICD-9 and OPS-301 went up to 1
4 percent, depending on the surgical field. The median number of cases per
code was between 2 and 4. The concentration of codes was enormous: 10 perce
nt of the codes were used for about 70 percent of the surgical procedures.
The distribution after an aggregation by digit was better with OPS-301 than
with ICD-9. The views with OPS-301 and ICD-9 were quite different.
Conclusion: Statistics based on ICD-9 or OPS-301 will not properly reflect
the morbidity in different surgical departments. Neither classification ade
quately represents the work done by surgical staff. This is because of an u
neven granularity in the classifications. The results demand a replacement
of the ICD-9 by an improved terminological system in surgery. The OPS-301 s
hould be maintained and can be used at least in the medium term.