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. 2024 Mar 22;6(1):e000202.
doi: 10.1136/bmjsit-2023-000202. eCollection 2024.

Distribution of case volumes in surgery: an analysis of the British Spine Registry

Chan Hee Koh  1   2   3   4 , William Muirhead  1   2 , Danyal Zaman Khan  1   2   4 , Hugo Layard Horsfall  1   2 , George Prezerakos  1   3   4 , Parag Sayal  1 , Hani J Marcus  1   2   4
Affiliations

Distribution of case volumes in surgery: an analysis of the British Spine Registry

Chan Hee Koh et al. BMJ Surg Interv Health Technol. .

Abstract

Objectives: To characterize the distribution of case volumes within a surgical field.

Design: An analysis of British Spine Registry.

Setting: 295 centers in England that conducted at least one spinal operation either within the NHS or private settings between 1 May 2016 and 27 February 2021.

Participants: 644 surgeons.

Main outcome measures: Mathematical descriptions of distributions of cases among surgeons and the extent of workforce-level case-volume concentration as a surrogate marker.

Results: There were wide variations in monthly caseloads between surgeons, ranging from 0 to average monthly high of 81.8 cases. The curves showed that 37.7% of surgeons were required to perform 80% of all spinal operations, which is substantially less than in fields outside of healthcare.With the COVID-19 pandemic, the case volumes of surgeons with the highest volumes dropped dramatically, whereas those with the lowest case numbers remained nearly unchanged. This, along with the relatively low level of case-volume concentration within spinal surgery, may indicate an inevitability of at least some level of surgical care being provided by the relatively lower volume surgeons.

Conclusions: While there is a reasonable degree of workforce-level case volume concentration within spinal surgery, with high volume spinal surgeons providing a large proportion of care, it is not clear whether a further concentration of case volumes into those few hands is possible or desirable.

Keywords: Health Care Quality, Access, and Evaluation; Health Policy; Health Services Research; Learning Curve.

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Conflict of interest statement

Competing interests: None declared.

Figures

Figure 1
Figure 1
Variations in monthly case volumes. (A) The mean of the monthly medians, monthly 75th centiles, and monthly maximums of surgeons and units. (B) A zoomed plot of monthly median and upper quartile for surgeons. (C) A zoomed plot of monthly median and upper quartile for units. Bars denote the mean. The error bars denote the 95% CIs.
Figure 2
Figure 2
Distribution of labor in British spinal surgery. (A) The distribution of a number of surgeons who perform a certain number of operations. (B) A log-log plot, with both axes on a long scale, for visual inspection for an inverse power law. (C) The distribution of number of units performing a given number of operations. (D) A log-log plot for the data in (C).
Figure 3
Figure 3
Pareto’s principle and Price’s law versus reality. (A) Comparing Pareto’s predictions with reality with regard to the proportion and numbers of surgeons performing 80% of all operations. (B) Comparing Pareto’s predictions with reality with regard to the proportion of units performing 80% of all operations. (C) Comparing Price’s predictions with reality with regard to the nth root of total number of surgeons and the numbers of surgeons performing 50% of all operations. (D) Comparing Price’s predictions with reality with regard to the nth root of total number of units and the numbers of units performing 50% of all operations.
Figure 4
Figure 4
Changes in distribution with COVID-19.
Figure 5
Figure 5
Changes in case volumes with COVID-19, grouped by monthly case volumes of surgeons and units. The individual surgeons and units are grouped by the monthly case numbers and tracked across the time periods above, with the first group being the largest comprising the largest number of lowest-volume surgeons/units performing the first 20% of all spinal operations. The second group is then the second largest, comprising the next group of low volume surgeons contributing to 20% of operations, and so on, until the final group comprises the small number of highest volume surgeons contributing to 20% of all operations. Whiskers indicate range (with outliers indicated by points), box the IQR and the middle line the median.
Figure 6
Figure 6
Geographical variations in case-volume concentration.
See this image and copyright information in PMC

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