Surgery for primary supratentorial brain tumors in the United States, 1988 to 2000: the effect of provider caseload and centralization of care

Abstract

Contemporary reports of patient outcomes after biopsy or resection of primary brain tumors typically reflect results at specialized centers. Such reports may not be representative of practices in nonspecialized settings. This analysis uses a nationwide hospital discharge database to examine trends in mortality and outcome at hospital discharge in 38,028 admissions for biopsy or resection of supratentorial primary brain tumors in adults between 1988 and 2000, particularly in relation to provider caseload. Multivariate analyses showed that large-volume centers had lower in-hospital postoperative mortality rates than centers with lighter caseloads, both for craniotomies (odds ratio [OR] 0.75 for a tenfold larger caseload) and for needle (closed) biopsies (OR 0.54). Adverse discharge disposition was also less likely at high-volume hospitals, both for craniotomies (OR 0.77) and for needle biopsies (OR 0.67). The annual number of surgical admissions increased by 53% during the 12-year study period, and in-hospital mortality rates decreased during this period, from 4.8% to 1.8%. Mortality rates decreased over time, both for craniotomies and for needle biopsies. Subgroup analyses showed larger relative mortality rate reductions at large-volume centers than at small-volume centers (73% vs. 43%, respectively). The number of US hospitals performing one or more craniotomies annually for primary brain tumors decreased slightly, and the number performing needle biopsies increased. There was little change in median hospital annual craniotomy caseloads, but the largest centers had disproportionate growth in volume. The 100 highest-caseload US hospitals accounted for an estimated 30% of the total US surgical primary brain tumor caseload in 1988 and 41% in 2000. Our findings do not establish minimum volume thresholds for acceptable surgical care of primary brain tumors. However, they do suggest a trend toward progressive centralization of craniotomies for primary brain tumor toward large-volume US centers during this interval.

Fig. 1

Effect of age on probability of death or discharge other than to home after surgery (craniotomy or needle biopsy) for primary brain tumor, plotted using local-likelihood fitting. Dashed line, mortality; dotted line, death or discharge to long-term care facility (LTF); solid line, death or discharge to long-term or short-term facility (STF).

Fig. 2

In-hospital mortality rates and probability of discharge other than to home as a function of hospital caseload of surgical primary brain tumor treatment, 1988 to 2000, ranked by quintile. Mortality rates for (A) craniotomy (P < 0.001) and (B) needle biopsy (P < 0.006). Discharge other than home for (C) craniotomy (P < 0.001) and (D) needle biopsy (P < 0.001). Error bars: 95% confidence intervals.

Fig. 3

Probability of mortality and discharge other than to home plotted as a function of patient age for highest- and lowest-volume-quintile hospitals. A, upper and lower panels. Craniotomy. B, upper and lower panels. Closed needle biopsy. Plots use local-likelihood fitting. The differences in mortality rates and hospital discharge disposition are present at all patient ages.

Fig. 4

Annual number of admissions for surgical treatment of primary brain tumors in nonfederal U.S. hospitals, 1988–2000. Circles, craniotomy; squares, needle biopsy; error bars, 95% confidence intervals.

Fig. 5

In-hospital mortality rates for surgical treatment of primary brain tumors in nonfederal U.S. hospitals, 1988 to 2000. A. Craniotomy. B. Needle biopsy. The decrease in mortality was significant in multivariate analysis both for craniotomy (P < 0.001) and for closed needle biopsy (P = 0.003). Error bars, 95% confidence intervals.

Fig. 6

Selected caseload percentiles for hospitals that performed at least one annual craniotomy. For example, the 90^th percentile case-load for hospitals in 1988 was 16, increasing to 22 in 2000. Caseload at the largest centers increased disproportionately during the study period.