Comparing the inter-observer reliability of the Tada formula among neurosurgeons while estimating the intracerebral haematoma volume

Objective: To compare the inter-observer reliability among neurosurgeons while estimating the intracerebral haematoma (ICH) volume by the Tada formula and assess its influence on predicting the severity and prognosis of various ICHs. Methods: We obtained clinical data from 262 consecutive patients with spontaneous ICH. The haematoma volume was independently calculated and compared by 3D Slicer and eight neurosurgeons. The inter-observer reliability was obtained by calculating the intraclass correlation coefficients (ICC) and Cohen's kappa score (kappa), within different shape and volume ICH subgroups. We conducted the receiver operating characteristic analysis to assess the predictive value of the ICH volume evaluated for clinical features, including the Glasgow Coma Scale at the onset of the disease, ICH-related surgical treatments, the length of stay in the intensive care unit, the length of hospitalisation, the modified Rankin Scale score at discharge, and in-hospital deaths. Results: The median haematoma volume was 17.4 ml (range, 7.3-34.7 ml). The estimated volumes were significantly different among neurosurgeons (p < 0.001). Six out of eight neurosurgeons demonstrated obvious deviations from the 3D Slicer software (p 0.001). Round (ICC: 0.947) and tapered (ICC: 0.954) haematomas were more consistently evaluated between the neurosurgeons. We observed a substantial strength of agreement between neurosurgeons with kappa 0.693 and ICC: 0.938 in the entire volume range, and slight to fair strength of agreement with kappa > 0.175 and ICC: 0.689 between 20 ml and 40 ml volume interval. All estimated volumes had a positive predictive value for clinical features, with the area under the curve > 0.5 (p < 0.05). However, the 3D Slicer software performed relatively better than most neurosurgeons. Conclusions: There exists a significant inter-observer variability among neurosurgeons when utilizing the Tada formula, thus demonstrating significant implications for ICH-related clinical practices and researches.