Disparities in glioblastoma survival by case volume: a nationwide observational study

Abstract

Introduction: High hospital case volumes are associated with improved treatment outcomes for numerous diseases. We assessed the association between academic non-profit hospital case volume and survival of adult glioblastoma patients.

Methods: From the nationwide Finnish Cancer Registry, we identified all adult (≥ 18 years) patients with histopathological diagnoses of glioblastoma from 2000 to 2013. Five university hospitals (treating all glioblastoma patients in Finland) were classified as high-volume (one hospital), middle-volume (one hospital), and low-volume (three hospitals) based on their annual numbers of cases. We estimated one-year survival rates, estimated median overall survival times, and compared relative excess risk (RER) of death between high, middle, and low-volume hospitals.

Results: A total of 2,045 patients were included. The mean numbers of annually treated patients were 54, 40, and 17 in the high, middle, and low-volume hospitals, respectively. One-year survival rates and median survival times were higher and longer in the high-volume (39%, 9.3 months) and medium-volume (38%, 8.9 months) hospitals than in the low-volume (32%, 7.8 months) hospitals. RER of death was higher in the low-volume hospitals than in the high-volume hospital (RER = 1.19, 95% CI 1.07-1.32, p = 0.002). There was no difference in RER of death between the high-volume and medium-volume hospitals (p = 0.690).

Conclusion: Higher glioblastoma case volumes were associated with improved survival. Future studies should assess whether this association is due to differences in patient-specific factors or treatment quality.

Keywords: Epidemiological study; Glioblastoma; Glioma; Malignant glioma; Mortality; Outcome.

Fig. 1

Proportion of persons living in high, medium, and low-volume hospital regions in Finland. Finland’s map to the left: people living in the red areas are being treated in low-volume hospitals, people living in the blue area are being treated in a medium-volume hospital, and people living in the green area are being treated in a high-volume hospital. Stars represent the locations of the five university hospitals. To the right: population distribution according to age in areas covered by a high-volume hospital (green), a medium-volume hospital (blue), and the mean of the low-volume hospitals (red). Number and proportion of persons < 18 years of age (bottom), 18–70 years of age (middle), and > 70 years of age (top)

Fig. 2

Trends in age-standardized glioblastoma incidence rates from 2000 to 2013 by case volume. From left to right: all age groups, elderly patients (> 70 years of age) and younger patients (≤ 70 years of age). The overall incidence of glioblastoma increased in the high-volume hospital but remained the same in the medium-volume and low-volume hospitals. Still, the incidence of glioblastoma in the medium-volume hospital increased markedly from 2011 onward

Fig. 3

Difference in relative survival between high-volume, medium-volume, and low-volume hospitals (2000–2013). Median overall survival time was longest in the high-volume hospital (9.3 months), followed by that in the medium-volume hospital (8.9 months) and that in the low-volume hospitals (7.8 months)

Fig. 4

Relative survival by volume status (high to the left, medium in the middle, and low to the right) in the periods of 2000–2006 and 2007–2013, separately for patients aged ≤ 70 and > 70 years