Het volume van chirurgische ingrepen en de impact ervan op ... - KCE

KCE Reports 113 Volume Outcome 181
RELATION BETWEEN SURGEON VOLUME AND REVISION RATE AT 18
MONTHS
The effects from the Cox proportional hazards model, with revision rate at 18 months
as dependent variable, are presented in Table 7.16. Low volume surgeons and medium
volume surgeons have a slightly higher revision rate when compared to high volume
surgeons: hazard ratio and 95%CI 1.213 (0.641, 2.295) for low volume compared to
high volume and 1.156 (0.782, 1.709) for medium volume compared to high volume,
respectively.
Table 7.16: Total hip arthroplasty: Results of regression: hazard ratio of
surgeon volume category on revision rate at 18 months
Model without adjustment for case mix Effect1 95% CI
Volume: low-volume (20 THR)
1.221 0.648 2.302
Medium-volume versus high–volume surgeon 1.148 0.779 1.693
Model with adjustment for case mix Effect 1 95% CI
Volume: low-volume (20 THR)
1.213 0.641 2.295
Medium-volume versus high–volume surgeon 1.156 0.782 1.709
Hazard Ratio 95% CI
Sex (male vs. female) 1.145 0.865 1.516
Age (increase of 1 year) 0.988 0.976 1.001
Charlson score (increase of 1 category) 0.968 0.742 1.264
715 vs. other PDX 2.034 0.507 8.163
733 vs. other PDX 2.814 0.667 11.868
1 Hazard ratio of volume category of surgeon on revision within 18 months
7.1.7 Discussion
7.1.7.1 External validation of the definition of the procedure
The external validation of our definition process is based on the data from the Alliance
of Christian Sickness Funds in which a total of 17 485 total hip replacements were
reported in Belgium in 1998. 312, 313 This number was obtained by extrapolation of the
claims data from the Christian Sickness Funds for the whole of Belgium. It included
elective and emergency THR and should therefore be compared with the 20 267 stays
selected on the basis of NIHDI procedure codes (see Table 5.2 on page 46). The
Christian Sickness Funds mentioned a yearly increase of 4.5% of the number of elective
THR and of 2% of the emergency THR, in Belgium, in the period 1990-1998. When such
a yearly increase is taken into account, their data become very similar to ours.
7.1.7.2 Summarized results of literature review
The systematic literature search identified six systematic reviews in which the VOA for
THR was studied. 1, 5, 59, 60, 62, 64 In all, these systematic reviews identified 20 primary
studies of which 4 were published between 2001 and 2004, 311, 314-316 and 7 between
1995 and 1999. 197, 309, 317-321 These articles were complemented with a limited number of
primary studies that were retrieved through the reference lists of the original 20
312, 322, 323
primary studies and through a search of grey literature.
On the basis of all six systematic reviews, it was concluded in Chapter 2 (see Table 2.2
on page 19) that there were conflicting results in relation to the volume-outcome
association between hospital volume and in-hospital mortality. The term “conflicting
results” is used because there is a mix of primary studies that indicate an inverse
relation with volume, others that indicate no relation, and others that indicate a direct
relation with volume (which means that an increase in volume is associated with higher
mortality). It was emphasised, however, that each systematic review had studied only a
very limited number of primary studies.