Objectives: Prompt assessment of consciousness levels is vitally important during the emergency care of stroke patients. The Japan Coma Scale (JCS) is a one-axis coma scale published in 1974 with outstanding simplicity. The hypothesis is that JCS is sufficient to predict stroke outcome. The aim of the study was to verify the predictability of JCS, which should help JCS attain international recognition.
Design: A cohort study.
Setting: A prefectural stroke registry.
Participants: We analysed 13 788 stroke patients identified from January 1999 to December 2009 inclusive in the entire Kyoto prefecture and registered in the Kyoto Stroke Registry (KSR).
Main outcome measures: We investigated the relationship between consciousness levels, based on JCS at stroke onset and activities of daily living (ADL) at 30 days or deaths within 30 days in a large population-based stroke registry. We calculated Spearman's coefficient for the correlation between JCS and the ADL scale, generated estimated survival curves by the Kaplan-Meier method and finally compared HRs for death within 30 days after onset, comparing patients with different conscious levels based on JCS.
Results: A total of 13 406 (97.2%) patients were graded based on JCS. JCS correlated to the ADL scale with Spearman's correlation coefficient of 0.61. HRs for death within 30 days were 1 (reference) (95% CIs), 5.55 (4.19 to 7.37), 9.54 (7.16 to 12.71) and 35.21 (26.10 to 44.83) in those scored as JCS0, JCS1, JCS2 and JCS3, respectively.
Conclusions: Using a single test of eye response, JCS has outstanding merits as a coma scale, that is, simplicity and applicability. The present study adds predictability for early outcome in stroke patients. JCS is valuable, especially in an emergency setting, when a prompt assessment of consciousness levels is needed.