Exploring the sources of 'missingness' in brain tissue monitoring datasets: an observational cohort study

Abstract

Objective: To investigate the frequency/category of missing electronic data in export files from patients admitted to the intensive care unit (ICU) with severe traumatic brain injury (TBI).

Research design: Observational cohort study.

Methodology: Patient data-streams for brain temperature (T(br)) and intracranial pressure (ICP) were analysed. Missing data was classified as: missing completely at random (MCAR), missing at random (MAR), missing not at random (MNAR).

Results: Sixty-two patients were studied; 60% of missing T(br) and ICP data events were attributed to electronic data acquisition 'faults'. Missing data rate ranged from 9-43% (median 25%). Cross-reference of missing data to clinical observation sheets and medical case notes shows that disconnection of sensors from monitors during critical events are common. Conclusions and implications for further research: Of concern for clinical management of patients with TBI is the detection of sudden changes in ICP or brain temperature; the parameters which forewarn of impending intracranial catastrophes. Missing data occurred at critical times of the patients stay in the ICU. This work should alert research clinicians of the need to scrutinize monitored physiological data to establish the percentage of missing values in order to obviate bias in the interpretation of results.