Table 1 Frequency (%) and incidence of medication prescription errors according to type of error at King Abdulaziz Medical City, Riyadh, Saudi Arabia

(A). Potentially harmful errors:

22.1 (9.0, 25.2)

Dose

   Overdose

249

47.3

   Missed dose

186

35.4

   Underdose

79

15.0

   Undecided dose

12

2.3

   Subtotal *

526

39.4

Route

12.0 (8.5, 15.5)

   Missed route

271

94.8

   Undecided route

11

3.8

   Inappropriate route

4

1.4

   Subtotal *

286

21.4

Frequency

5.4 (1.6, 9.2)

   Missed frequency

95

73.6

   High frequency

17

13.2

   Low frequency

11

8.5

   Undecided frequency

6

4.7

   Subtotal *

129

9.7

Incompatibility

45

3.4

1.9 (-2.1, 5.9)

Wrong drug selection

41

3.1

1.7 (-2.2, 5.6)

Duplicate therapy

24

1.8

1.00 (-3.1, 4.1)

(B) Non-harmful errors:

Clarity

272

20.4

11.4 (7.8, 15.0)

Miscellaneous

10

0.8

0.4 (-5.8, 6.6)

TOTAL

1333

100.0

56.0 (54.2,57.8)