The Therapy Intensity Level scale for traumatic brain injury: clinimetric assessment on neuro-monitored patients across 52 European intensive care units
Authors: Bhattacharyay Shubhayu , Beqiri Erta , Zuercher Patrick , Wilson Lindsay , Steyerberg Ewout W , Nelson David W , Maas Andrew I R , Menon David K , Ercole Ari ,   the CENTER-TBI investigators and participants
Published: August 2023

Intracranial pressure (ICP) data from traumatic brain injury (TBI) patients in the intensive care unit (ICU) cannot be interpreted appropriately without accounting for the effect of administered therapy intensity level (TIL) on ICP. A 15-point scale was originally proposed in 1987 to quantify the hourly intensity of ICP-targeted treatment. This scale was subsequently modified – through expert consensus – during the development of TBI Common Data Elements to address statistical limitations and improve usability. The latest, 38-point scale (hereafter referred to as TIL) permits integrated scoring for a 24- hour period and has a five-category, condensed version (TIL(Basic)) based on qualitative assessment. Here, we perform a total- and component-score analysis of TIL and TIL(Basic)to: (1) validate the scales across the wide variation in contemporary ICP management, (2) compare their performance against that of predecessors, and (3) derive guidelines for proper scale use. From the observational Collaborative European NeuroTrauma Effectiveness Research in TBI (CENTER-TBI) study, we extract clinical data from a prospective cohort of ICP-monitored TBI patients (n=873) from 52 ICUs across 19 countries. We calculate daily TIL and TIL(Basic)scores (TIL24and TIL(Basic)24, respectively) from each patient’s first week of ICU stay. We also calculate summary TIL and TIL(Basic)scores by taking the first-week maximum (TILmaxand TIL(Basic)max) and first-week median (TILmedianand TIL(Basic)median) of TIL24and TIL(Basic)24scores for each patient. We find that, across all measures of construct and criterion validity, the latest TIL scale performs significantly greater than or similarly to all alternative scales (including TIL(Basic)) and integrates the widest range of modern ICP treatments. TILmedianoutperforms both TILmaxand summarised ICP values in detecting refractory intracranial hypertension (RICH) during ICU stay. The RICH detection thresholds which maximise the sum of sensitivity and specificity are TILmedian≥7.5 and TILmax≥14. The TIL24threshold which maximises the sum of sensitivity and specificity in the detection of surgical ICP control is TIL24≥9. The median scores of each TIL component therapy over increasing TIL24reflect a credible staircase approach to treatment intensity escalation, from head positioning to surgical ICP control, as well as considerable variability in the use of cerebrospinal fluid drainage and decompressive craniectomy. Since TIL(Basic)maxsuffers from a strong statistical ceiling effect and only covers 17% (95% CI: 16–18%) of the information in TILmax, TIL(Basic)should not be used instead of TIL for rating maximum treatment intensity. TIL(Basic)24and TIL(Basic)mediancan be suitable replacements for TIL24and TILmedian, respectively (with up to 33% [95% CI: 31–35%] information coverage) when TIL assessment is infeasible. Accordingly, we derive numerical ranges for categorising TIL24scores into TIL(Basic)24scores. In conclusion, our results validate TIL across a spectrum of ICP management and monitoring approaches. TIL is a more sensitive surrogate for pathophysiology than ICP and thus can be considered an intermediate outcome after TBI.