Is there evidence for a surgeon learning curve for endothelial keratoplasty in Australia?

Importance: Expected outcomes from endokeratoplasty may vary with surgeon experience. Background: It was explored whether a surgeon learning curve exists for Descemet stripping endothelial keratoplasties (manual or automated) performed in Australia. Design: This is a prospective cohort study, with various clinical settings. Participants: There were 2139 recipients of 2615 endothelial grafts, registered by 85 surgeons between January 2006 and December 2013. Methods: Kaplan–Meier survival analyses and Cox proportional hazards regression were used to examine longitudinal graft survival. Manual and automated Descemet stripping endothelial keratoplasties were analysed together. Pearson chi-squared analyses were performed to examine differences amongst groups. Continuity correction was used for 2 × 2 tests, and statistical significance was set at P < 0.05 (two-sided). Main outcome measure: The main parameter measured was endothelial graft survival. Results: Survival of the first 56 registered grafts was significantly poorer than survival of subsequent grafts (χ² = 8.83, df = 1, P = 0.003), when data were combined for all surgeons. Surgeon workload influenced graft survival significantly (P < 0.001). This variable was retained in multivariate analysis designed to investigate independent factors influencing graft survival. Primary non-functioning grafts were significantly less likely to be reported for endokeratoplasties performed by surgeons with more than 56 registered grafts, compared with those registering 56 or fewer grafts (4.3% vs. 8.5%; χ² = 18.38, df = 1, P < 0.001). Conclusions and Relevance: Our findings suggest that for less experienced or low-volume surgeons, longitudinal graft survival improved once 56 or more endokeratoplasties had been performed, indicative of a learning curve. The learning curve was less apparent for surgeons with 57 or more Descemet stripping endothelial keratoplasties and/or Descemet stripping automated endothelial keratoplasties registered during the 8-year study period. Different learning curves may be anticipated for these two groups of surgeons.