Comparison of ‘Serial 7’s Subtraction’ and “Sam-Chun-Ri-Gang-San” Backward for Evaluation of in Primary Medicine

Abstract

Background: There are two variations in the attention subitem of the Mini-Mental State Exam (MMSE): ‘serial 7’s subtraction and “sam-chun-ri-gang-san” backward. At a scale of one to five, they can be used interchangeably, which inevitably brings a considerable difference in results. Thus, we compared the scores of the ‘serial 7’s subtraction’ and the “sam-chun-ri-gang-san” backward and analyzed the influence of sociodemographic factors on the differences. Methods: We administered the Korean MMSE including the two types of attention item: serial 7’s and “sam-chun-rigang-san” backward to 239 community-dwelling elderly people aged 65 or older in Kyung Hee University Medical Center and four Seoul senior centers and analyzed the difference from June 2012 to July 2012. Results: The score for “sam-chun-ri-gang-san” backward (2.5±2.1) was lower than that of the serial 7’s (3.4±1.7) by a mean point of 0.9±1.9. The score of “sam-chun-ri-gang-san” backward was zero in 31.4% of the subjects. However, only 9.6% scored zero on the serial 7’s. The ratio of the same scores between two tasks was 36.0%. Education was the primary source of variance on difference score, followed by the number of family. There was no significant effect of age or gender when the score of difference was analyzed by multiple regression. Conclusion: In this study, subjects tended to outperform the serial 7’s in general. Upon administering “sam-chun-rigang-san” backward instead of serial 7’s due to the preference of the patient, we should take into account that the score of “sam-chun-ri-gang-san” backward was 0.9 point (mean value) lower than serial 7’s to ensure appropriate interpretation of MMSE score.