Objective: This study quantitatively analyzes the factors causing dispensing errors in community pharmacies and explores the characteristics of these factors and their order of importance.
Design and Methods: We collected data records on the contents and causes of dispensing errors as reported between April and July 2009 by a total of 320 pharmacists at 56 stores of two pharmacy chains (15 stores in Hokkaido and 41 stores in the Kansai area).  We focused on the following three types of dispensing error: 1) “measurement error”, 2) “wrong drug dispensing error” and 3) “wrong dosage form specification error”.  We conducted multiple regression analyses and discriminant analyses with occurrence frequency of each type of error as dependent variables and count frequency of each causal factor as independent variables.
Results: The result of the multiple regression analyses indicated that the primary causes of the three types of errors in order of strength of the regression coefficients were as follows.  For “measurement error”: 1) pharmacist’s wrong assumption and 2) calculation error; for “wrong dosage form specification error”: 1) insufficient confirmation of prescription and 2) pharmacist’s wrong assumption; for “wrong drug dispensing error”: 1) pharmacist’s wrong assumption and 2) insufficient confirmation of prescription.  The results of the discriminant analysis indicated that only for the discriminant coefficient between “wrong dosage form specification error” and “wrong drug dispensing error” no significant difference in the mean was found (p=0.539).
Conclusions: Results show that partly different factors cause “measurement error” as compared with the two other types of dispensing errors.  In addition, while basically the same factors were found to cause “wrong drug dispensing error” and “wrong dosage form specification error,” there was a difference in the order of importance of these factors.  This study uncovered differences in terms of causal factors affecting each dispensing error type.