Dear Editor

The work by Habib et al [1] is a timely one with the increasingly important role of assessment and monitoring of the quality of health service delivery and outcomes. As they indicate, little work exists in ophthalmology on the associations between surgical volume and outcomes. This may partly be due to the low rate of serious complications with ophthalmic surgery such as cataract extraction. However, with large numbers of patients undergoing cataract surgery, ophthalmologists cannot afford to become complacent as even relatively low complication rates have the potential to harm many in the community. Currently, in Western Australian hospitals, phacoemulsification with intraocular lens insertion is the most commonly performed surgical procedure.

The lack of significant associations between an individual surgeon’s surgical volume and complication rate in contrast to that shown for the pooled data [1] may be due to less statistical power in the former group and is a limitation with any single centre study. Our population-based work into endophthalmitis after cataract surgery showed marked differences in endophthalmitis incidence across different surgical centres. However, we did not find any association between cataract surgery volume and endophthalmitis risk either before [2] or after adjustment for case-mix [3].

These contrasting results highlight the importance of selecting valid outcome measures when the monitoring of clinician performance is being considered. Should we choose a surrogate measure, a clinical endpoint or both? The degree to which any complication is within the control of the surgeon will vary. If a complication is multifactorial, such as endophthalmitis, then the entire system of care is just as important as a surgeon’s technical expertise.

Despite highly publicised failures of care [4], it is important that we do not succumb to a simplistic populist model of “someone to blame”. Although monitoring surgeon performance is an important aspect of any quality improvement effort, equally important is a better understanding and attention to the operating environment and prevailing organisational culture.

References

(1) Habib M, Mandal K, Bunce CV, Fraser SG. The relation of volume with outcome in phacoemulsification surgery. Br J Ophthalmol 2004;88:643- 646.

(2) Morlet N, Li J, Semmens JB, Ng J. The Endophthalmitis Population Study of Western Australia (EPSWA): First Report. Br J Ophthalmol 2003;87:574-576.

(3) Li J, Morlet N, Ng JQ, Semmens JB, Knuiman MW. Significant nonsurgical risk factors for endophthalmitis after cataract surgery: EPSWA fourth report. Invest Ophthalmol Vis Sci 2004;45:1321-1328.

(4) Smith R. One Bristol, but there could have been many. BMJ 2001;323:179-180