[Influencing factors on operating times for metal bar removal after Nuss repair]

Metal bar removal after the Nuss repair procedure is prone to be cancelled in cases of operating time shortages due it being suitable to be postponed without harming patients. Consequently, planning operation times as exactly as possible could be one solution.

Statistical modelling of operation times of metal bar removal after Nuss repair using the prespecified independent predictors of age, sex, intraoperative complications, and number of implanted metal bars.

We included all patients whose operation notes included an operation time, which was modelled via linear regression and subject to internal validation via bootstrap. Exploratory analyses also consisted of the surgeon's experience, the number of stabilizers, the body mass index, and preceding re-do surgery for bar dislocation.

We included 265 patients (14% ♀) with a median age of 19 years (interquartile range 17-20 years), of whom 81% had 1 and 17% had 2 metal bars removed. The prespecified regression model was statistically significant (likelihood ratio 56; df = 5; P < 0.001) and had a bias corrected R² of 0.148. Patient age influenced operation times by 2.1min per year of life (95% confidence interval 1.3-2.9min; P < 0.001) and 16min per explanted metal bar (95% confidence interval: 10-22min; P < 0.001).

The patient-specific factors of age and the number of explanted metal bars influenced the operation times and can be included into scheduling operation times.