The relation of volume and outcome in trabeculectomy

Higher case volume has been associated with improved outcomes for a number of procedures. This study was designed to investigate whether this relationship existed for trabeculectomy.

The study was retrospective and conducted at an ophthalmic unit in the UK. All patients who had unenhanced trabeculectomy between 1996 and 2000 were identified. From their notes, the surgeon who performed the trabeculectomy was ascertained as were any unplanned interventions (eg conjunctival suturing, anterior chamber reformation, repeated attendances) within the first month of surgery.

Two hundred and eleven trabeculectomies were performed over the study period. Twenty nine had unplanned interventions within the first postoperative month. Analysis of the data indicated that surgeons who performed less than eight operations per year had more complications than those who performed more than 10 per annum. This difference was only significant (chi(2)=4.0, P=0.045) when the data were aggregated. When separated per year, although not significant, the complication rate of the lower volume group was always higher than the group performing more than 10 per year.

The results suggest that trabeculectomy can be added to the list of procedures in which larger case volume is associated with fewer early complications and potentially a better outcome. The findings, if replicated, tend to strengthen the argument for subspecialisation in glaucoma with its implications for training and revalidation.