Development and Validation of a Nomogram for Predicting Second Surgery in Patients with Concomitant Esotropia

Introduction This study developed and validated a nomogram for predicting the risk of second surgery in patients with concomitant esotropia (CE) based on a cohort in Beijing. Methods In this retrospective cohort study, the inpatient and outpatient medical records of 419 patients with CE who underwent surgery at the Peking University First Hospital between January 1, 2005 and December 31, 2009 were collected. A total of 357 CE cases were included. For those cases 70% were randomly assigned to the training set ( n = 234) and 30% to the validation set ( n = 123). Demographic and clinical variables were ascertained at hospital admission and discharge and screened using multivariate Cox proportional hazards regression analysis to construct predictive models and generate a 1-, 4-, and 8-year overall survival nomogram. This nomogram provided an estimate of the risk of second surgery in patients with surgically treated CE. Internal validation was conducted using the concordance index (C-index) and calibration curve for the training and validation sets. Results Six independent prognostic factors were identified, namely age at surgery, age at onset, amblyopia, deviation angles, surgical amount, and deviation angles 1 week after surgery, and these were entered into the nomogram. The proposed nomogram showed favorable discrimination and accuracy in the training and validation sets. The C-indexes of the training and validation sets were 0.84 (95% CI 0.79–0.89) and 0.80 (95% CI 0.78–0.82), respectively. Conclusions The proposed nomogram can serve as a predictive tool for prognostic evaluation of CE surgery.