Retinal detachment repair by vitrectomy: Simplified formulae to estimate the risk of failure

Abstract

Aim: Devise simplified formulae, using preoperative clinical data, to give risk estimates of (1) failure and (2) proliferative vitreoretinpathy (PVR) following primary retinal detachment repair by vitrectomy. Methods: 641 patients were analysed as part of an RCT investigating use of 5-fluorouracil and low-molecular-weight heparin. Treatment status had no effect on success rates and did not therefore form part of the analyses. Preoperative risk factors for surgical failure and for PVR within 6 months of retinal detachment surgery were identified, and a multiple variable logistic regression model developed. Further analyses were performed to devise a simple points system to produce risk estimates of failure. Results: Three risk factors were related to failure - previous lens extraction (p=0.046), grade C PVR (p=0.039) and extent of detachment (p<0.001). Three risk factors were also related to failure due to PVR - vitreous haemorrhage (p=0.088), grade C PVR (p=0.044) and extent of detachment (p<0.001). There was good agreement between risk estimates produced by the points system and those calculated directly using a multivariate regression model. The points-system model gave an area under the receiver operating characteristic curve of 0.658. The receiver operating characteristic curve for the PVR model gave an area under the curve of 0.8399 suggesting greater diagnostic value. Conclusions: A simple points system may be used as a clinical guide to identify patients at higher risk of failure following retinal detachment repair by vitrectomy. This may help clinicians select appropriate surgical approaches and stratify cases in research and surgical training.