The Short Orientation-Memory-Concentration Test: a study of its reliability and validity.

Objective: To establish the limits of intra-observer test-retest reliability of the Short Orientation-Memory-Concentration Test (SOMC), and to investigate the relationship of performance on the SOMC with a test of verbal memory.

Design: Each patient was assessed twice by the same assessor over an interval of 3-7 days.

Setting: Two specialist rehabilitation units concerned with patients with severe and/or complex disability arising from neurological disease.

Subjects: Thirty-eight patients aged 17-63 years, 25 being men, with a variety of neurological diseases. The Barthel Activities of Daily Living Index score ranged from 0 to 20, median 10.5.

Measures: The Short Orientation-Memory-Concentration Test, the Barthel Activities of Daily Living Index and the paragraph recall subtest of the Rivermead Behavioural Memory Test (RBMT).

Results: There was a slight but statistically significant (p <0.01) improvement in the score of 2 points (out of 28) between the two test occasions, but this was not related to the interval between testing or to the mean score of the two tests. The scores differed by as much as +10 to -8, but most patients (n = 35; 92%) showed a difference between -2 and +6 points. The SOMC scores were correlated with the RBMT paragraph recall immediate and delayed scores (r = 0.74) but the scatterplot showed considerable variation.

Conclusion: If used by the same observer, changes in the SOMC score are likely to reflect a real difference if it increases by more than 6 points or decreases by more than 2 points. The SOMC does seem to reflect verbal memory.