The cataract national data set electronic multi-centre audit of 55,567 operations: case-mix adjusted surgeon's outcomes for posterior capsule rupture

Abstract

Aims: To develop a methodology for case-mix adjustment of surgical outcomes for individual cataract surgeons using electronically collected multi-centre data conforming to the cataract national data set (CND).

Methods: Routinely collected anonymised data were remotely extracted from electronic patient record (EPR) systems in 12 participating NHS Trusts undertaking cataract surgery. Following data checks and cleaning, analyses were carried out to risk adjust outcomes for posterior capsule rupture rates for individual surgeons, with stratification by surgical grade.

Results: A total of 406 surgeons from 12 NHS Trusts submitted data on 55,567 cataract operations between November 2001 and July 2006 (86% from January 2004). In all, 283 surgeons contributed data on >25 cases, providing 54,319 operations suitable for detailed analysis. Case-mix adjusted results of individual surgeons are presented as funnel plots for all surgeons together, and separately for three different grades of surgeon. Plots include 95 and 99.8% confidence limits around the case-mix adjusted outcomes for detection of surgical outliers.

Conclusions: Routinely collected electronic data conforming to the CND provides sufficient detail for case-mix adjustment of cataract surgical outcomes. The validation of these risk indicators should be carried out using fresh data to confirm the validity of the risk model. Once validated this model should provide an equitable approach for peer-to-peer comparisons in the context of revalidation.

Figure 1

Average case complexity profiles for each surgeon's case-mix calculated as if all operations had been carried out by a consultant for each of the 283 eligible surgeons contributing >25 cases.

Figure 2

Difference between observed PCR rate and expected PCR rate for 283 surgeons contributing N>25 cases, total N=54 319 operations. Positive % values indicate a rate higher than that expected (poorer than expected performance), negative values indicate better than expected performance. The wide spread to the left demonstrates uncertainty where number of cases is small.

Figure 3

Adjusted funnel plot for all surgeons: ratio of observed to expected number of operations complicated by PCR vs expected number of complications for each of 283 surgeons. Risk adjustment accounts for patient characteristics and grade of surgeon. A secondary ‘x-axis' above the plot indicates the approximate volume of cases based on the overall PCR rate=1.92% (total N=54 319 operations).

Figure 4

Adjusted funnel plot for independent surgeons: ratio of observed to expected number of operations complicated by PCR vs expected number of complications for 108 independent surgeons. A secondary ‘X-axis' above the plot indicates the approximate volume of cases based on the overall PCR rate=1.41% (N=36 485 operations).

Figure 5

Adjusted funnel plot for senior trainee surgeons: ratio of observed to expected number of operations complicated by PCR vs expected number of complications for 140 senior trainee surgeons. A secondary ‘X-axis' above the plot indicates the approximate volume of cases based on the overall PCR rate=2.48% (N=15 277 operations).

Figure 6

Adjusted funnel plot for junior trainee (SHO) surgeons: ratio of observed to expected number of operations complicated by PCR vs expected number of complications for 35 junior trainee surgeons. A secondary ‘X-axis' above the plot indicates the approximate volume of cases based on the overall PCR rate=5.1% (N=2557 operations).