# Surgeon-specific differences in recurrence rates among patients undergoing burr hole evacuation for chronic subdural hematoma

## TL;DR

This study finds that surgeon-specific factors may influence recurrence rates in chronic subdural hematoma surgeries, even when techniques are standardized.

## Contribution

The study introduces a novel approach to quantify surgeon-specific variability in surgical outcomes for chronic subdural hematoma.

## Key findings

- Surgeon-specific clustering explained 61% of recurrence variance via GEE analysis.
- Bayesian modeling showed surgeon differences accounted for 14% of total recurrence variance.
- Findings suggest individual surgical technique impacts cSDH outcomes despite standardized procedures.

## Abstract

Chronic subdural hematoma (cSDH) frequently recurs. Numerous studies have investigated the influence of various factors on the likelihood of recurrence, yet the potential influence of individual surgeon identity beyond general experience level remains unclear.

To evaluate whether surgeon-specific differences contribute to recurrence rates whilst accounting for standardized technique and known patient-/procedure-related factors.

Retrospective analysis of burr hole evacuation for cSDH or hygroma at a single tertiary center. Standardized surgical technique involved two burr holes with subdural lavage and drainage placement. Primary outcome was symptomatic recurrence necessitating redo surgery. Surgeon-specific variability in recurrence was assessed via three statistical methods: risk-standardized observed-to-expected (O/E) ratios, logistic generalized estimating equations (GEE), and hierarchical Bayesian logistic modeling, adjusted for covariates.

Among 116 patients (age = 78.0 years, 75.0 % = male, 26.7 % = bilateral procedures), symptomatic recurrence occurred in 15 cases (12.9 %). Risk-standardized-O/E recurrence ratios varied from 0.00 to 1.65, with wide confidence intervals indicating uncertainty, but all within expected ranges (median O/E = 1.11, IQR = 0.60–1.45). GEE analysis demonstrated significant surgeon-specific clustering (ICC = 0.61, large effect), indicating between-surgeon differences could explain more than half of the remaining variance in recurrence. Bayesian hierarchical modeling showed moderate surgeon-specific clustering with an ICC = 0.14, indicating that between-surgeon differences accounted for approximately 14 % of total variance in recurrence.

Our study demonstrates modest yet measurable surgeon-specific differences in recurrence rates following standardized burr-hole evacuation for cSDH. These findings support further investigation into surgeon-specific variability, particularly for more complex procedures, to identify actionable technical differences and optimize surgical outcomes universally.

•Our analytical approach demonstrates moderate between-surgeon differences in recurrence rates of chronic subdural hematoma.•Despite small sample size, findings indicate individual neurosurgical technique influences cSDH outcomes.•The study lays the groundwork for larger multicenter studies to quantify between-surgeon differences.

Our analytical approach demonstrates moderate between-surgeon differences in recurrence rates of chronic subdural hematoma.

Despite small sample size, findings indicate individual neurosurgical technique influences cSDH outcomes.

The study lays the groundwork for larger multicenter studies to quantify between-surgeon differences.