A comparative study of the Reaction Level Scale (RLS 85) with Glasgow Coma Scale (GCS) and Edinburgh-2 Coma Scale (modified) (E2CS(M))

Abstract

In this work a new coma scale for the assessment of responsiveness in acute brain disorders, constructed near the year 1985 by Scandinavian investigators, the Reaction Level Scale (RLS85), is compared with two other coma scales namely: (i) the Glasgow Coma Scale: (GCS); (ii) the Edinburgh-2 Coma Scale, after modification: (E2CS(M)). The study proceeded in the form of a statistical analysis of assessments made on 46 patients according to RLS85 and GCS (i.e., when comparison was with GCS) and on 28 patients according to RLS85 and E2CS(M). In all 74 cases two physicians participating as "observers" carried out the assessments. They were both contacting the patient--not together but--successively within a time interval of less than 20'. Hence the data appeared as "pairwise" observations for any of the three scales above. The results of the analysis, arising from a rather strict statistical reasoning, can be summarized as follows: (1) The rank correlation coefficient r(s) between: (i) RLS85 and GCS sum score, (ii) RLS85 and E2CS(M), was found to be at a satisfactory level meaning that all three scales indicate almost the same "ranking order of severity". (2) Reliability was compared by taking into account as to what extent the two observers agreed on RLS85 and--simultaneously--disagreed on the other scale. The "sign" test was applied and as a result RLS85 proved to be more reliable than; (i) GCS (EMY profile), (ii) GCS sum score, and (iii) E2CS(M), in all the above mentioned at a high level of significance. (3) Apart from the test above, some values of the index kappa (kappa) of interobserver agreement were calculated. Those corresponding to RLS85 are considerably higher. In particular the overall value based on 74 pairwise assessments amounted to kappa = 0.733 associated with a standard error sigma(kappa) = 0.061. This was a satisfactory result regarding the features of RLS85. (4) As far as coverage is concerned, again--by the "sign" test--the predominance of RLS85 versus GCS (EMY profile) was accepted.