title: 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).
  
  
  METHODS
  Observational cohort study.
  
  
  METHODS
  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.
authors.affiliation: Yong Loo Lin School of Medicine, National University of Singapore. charmaine_childs@nuhs.edu.sg
authors.forename: Charmaine
authors.initials: C
authors.lastname: Childs
authors.forename: Angela Li Ching
authors.initials: AL
authors.lastname: Ng
authors.forename: Kun
authors.initials: K
authors.lastname: Liu
authors.forename: Jianxin
authors.initials: J
authors.lastname: Pan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000378:metabolism / Q000503:physiopathology*; D001930:Brain Injuries / Q000378:metabolism / Q000503:physiopathology*; D015331:Cohort Studies; D016208:Databases, Factual / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D007427:Intracranial Pressure; D008297:Male; D019300:Medical Errors / Q000706:statistics & numerical data; D008875:Middle Aged; D008991:Monitoring, Physiologic; D020379:Risk Adjustment; D015599:Trauma Severity Indices; D055815:Young Adult