improving interrater agreement about brain microbleeds: development of the Brain Observer MicroBleed Scale (BOMBS).
OBJECTIVE
If the diagnostic and prognostic significance of brain microbleeds (BMBs) are to be investigated and used for these purposes in clinical practice, observer variation in BMB assessment must be minimized.


METHODS
Two doctors used a pilot rating scale to describe the number and distribution of BMBs (round, low-signal lesions, <10 mm diameter on gradient echo MRI) among 264 adults with stroke or TIA. They were blinded to clinical data and their counterpart's ratings. Disagreements were adjudicated by a third observer, who informed the development of a new Brain Observer MicroBleed Scale (BOMBS), which was tested in a separate cohort of 156 adults with stroke.


RESULTS
In the pilot study, agreement about the presence of >/=1 BMB in any location was moderate (kappa=0.44; 95% CI, 0.32-0.56), but agreement was worse in lobar locations (kappa=0.44; 95% CI, 0.30-0.58) than in deep (kappa=0.62; 95% CI, 0.48-0.76) or posterior fossa locations (kappa=0.66; 95% CI, 0.47-0.84). Using BOMBS, agreement about the presence of >/=1 BMB improved in any location (kappa=0.68; 95% CI, 0.49-0.86) and in lobar locations (kappa=0.78; 95% CI, 0.60-0.97).


CONCLUSIONS
Interrater reliability concerning the presence of BMBs was moderate to good, and could be improved with the use of the BOMBS rating scale, which takes into account the main sources of interrater disagreement identified by our pilot scale.
Cordonnier
Charlotte
C
Division of Clinical Neurosciences, Western General Hospital, Edinburgh EH4 2XU, UK.
Potter
Gillian M
GM
Jackson
Caroline A
CA
Doubal
Fergus
F
Keir
Sarah
S
Sudlow
Cathie L M
CL
Wardlaw
Joanna M
JM
Al-Shahi Salman
Rustam
R
D000368:Aged; D001160:Arterioles / Q000473:pathology* / Q000503:physiopathology; D001921:Brain / Q000098:blood supply / Q000473:pathology* / Q000503:physiopathology; D002545:Brain Ischemia / Q000150:complications; D002536:Cerebral Arteries / Q000473:pathology* / Q000503:physiopathology; D002540:Cerebral Cortex / Q000098:blood supply / Q000473:pathology / Q000503:physiopathology; D015331:Cohort Studies; D003951:Diagnostic Errors / Q000517:prevention & control; D005260:Female; D006801:Humans; D020300:Intracranial Hemorrhages / Q000473:pathology* / Q000503:physiopathology; D002546:Ischemic Attack, Transient / Q000150:complications; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000592:standards*; D008297:Male; D008833:Microcirculation / Q000502:physiology; D008875:Middle Aged; D015588:Observer Variation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D020521:Stroke / Q000150:complications