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

KCE Reports 113 Volume Outcome 135
Table 6.7: CEA/CAS: Correlation-corrected logistic regression (GEE)
estimates of determinants of in-hospital mortality
Model without adjustment for case mix Effect 1 95% CI
Hospital volume (increase of 10%) -4.59 -10.51 1.33
Model with adjustment for case mix Effect 1 95% CI
Hospital volume (increase of 10%) -5.28 -11.95 1.38
Odds Ratio 95% CI
Sex (male vs female) 0.77 0.39 1.51
Age (increase of 1 year) 1.09 1.03 1.17
Charlson score (increase of 1 category) 2.36 1.68 3.32
CAS vs CEA 0.70 0.26 1.88
1 Effect of 10% increase in volume on the odds of mortality
The association between volume and in-hospital mortality is not robust, as it is sensitive
to the one low volume-high mortality centre and the two high volume-low mortality
centres, as shown in Table 6.8. When these three centres are excluded, the effect of
volume virtually disappears (-1.3%).
Table 6.8: CEA/CAS: Sensitivity analysis (exclusion of 3 centres), Results of
logistic regression: relative effect of 10% increase volume on mortality
Model without adjustment for case mix Effect 1 95% CI
Hospital volume (increase of 10%) -1.32 -7.75 5.11
Model with adjustment for case mix Effect 1 95% CI
Hospital volume (increase of 10%) -1.31 -8.96 6.35
1 Effect of 10% increase in volume on the odds of mortality
The analyses presented above might be confounded by differences in length of stay
between low volume and high volume centres. Therefore, additional sensitivity analyses
were performed on the approximate 30-day mortality according to international volume
thresholds (for CEA only, used by AHRQ and Leapfrog, see discussion section page
137). As shown in Table 5.12, these analyses confirm the results presented above: one
single very high volume centre has 0% mortality, and no differences are observed with
respect to centres below or above the AHRQ cut off of 50 CEA per year.
Table 6.9: CEA: in-hospital and 30-day mortality per centre, based on
international volume thresholds
Cut off Hospital volume Number Number Approximate 30-
category centres patients day mortality
number %
AHRQ cut off 50/year 1-50 CEA/year 97 1964 24 1.22
51-100 CEA/year 11 721 8 1.11
AHRQ and
Leapfrog cut off
101/year ≥ 101 CEA/year 1 119 0 0.00
Results based on 2 804 patients with linkage to IMA data
The association between surgeon volume and outcome is not analysed because the
number of events (i.e. death) is too low compared to the number of surgeons (31
events for 236 surgeons).