The association of acute and chronic phase cerebrovascular reactivity with patient reported quality of life following moderate-to-severe traumatic brain injury

Global outcomes have been reported to be associated with cerebrovascular reactivity (CVR) in the acute phase following moderate and severe traumatic brain injury (TBI). The association of CVR in the acute and chronic phase of injury with patient-reported health-related quality of life metrics (HRQOL) metrics has never been explored. The aim of this study is to examine the association of CVR, as measured by the cerebral oxygen indices (COx and COx_a), in the acute and chronic phase following moderate and severe TBI, with patient reported HRQOL. In this prospective cohort study, performed in a Canadian quaternary care center, the association between continuous acute and chronic phase CVR with patient reported HRQOL outcomes following moderate and severe TBI was examined. The main outcomes of interest of this study were validated measures of patient-reported HRQOL over various domains as measured by both the 12-Item Short-Form Health Survey (SF-12) and a Quality of Life after Brain Injury (QOLIBRI) questionnaire. In the 29 subjects of this cohort, acute phase CVR was found to be significantly more active in those with a favorable Mental Component Summary (MCS) scores of the SF-12 at early follow-up when measured by COx (-0.015 [IQR: -0.067 to 0.032] vs 0.040 [IQR: 0.019 to 0.137] for Favorable first MCS vs Unfavorable respectively; Mann-Whitney U test p-value = 0.046) and COx_a (0.038 [IQR: 0.009 to 0.062] vs 0.112 [IQR: 0.065 to 0.167] for Favorable first MCS vs Unfavorable respectively; Mann-Whitney U test p-value = 0.014). Further, multivariable logistic regression analysis found acute phase COx and COx_a to improve model performance when predicting favorable versus unfavorable early MCS scores over established parameters such as age and measures of injury severity. Associations between outcomes and chronic phase CVR were limited, potentially due to short recording periods. This is the first ever pilot study to identify a relationship between acute phase CVR following moderate-to-severe TBI with mental and cognitive outcomes as experienced by patients. Given the small cohort, these findings will need to be confirmed in a larger multicenter study. This highlights the need for additional examination of the role dysfunctional CVR may play in mental and cognitive outcomes, as well as patient-reported outcomes more generally following TBI.