Table 2.

Subgroup analysis of rates of prescribing errors in each category

Category	Total	Prescriptions with error	Total error ratesa	P value	OR [95% CI]
No. of drug orders per prescriptionb				0.001c	1.14 [1.06–1.23]
1	70,540	200	0.28%
2	40,630	124	0.31%
3	22,101	101	0.46%
4	11,215	52	0.46%
5	5401	32	0.59%
6	564	1	0.18%
7	101	0	0.00%
8	31	0	0.00%
9	23	0	0.00%
10	5	0	0.00%
Total	150,611	510	0.34%
Age groups of patients				0.09c
Neonate (~ 28 days)	6038	11	0.18%	Reference
Infant (29 days to 12 months)	17,218	72	0.42%	0.01	2.33 [1.23–4.40]
Child (1 to 12 years)	41,292	166	0.40%	0.02	2.03 [1.10–3.76]
Adolescent (13 to 18 years)	700	2	0.29%	0.57	1.57 [0.34–7.36]
Adult (18 year~)	85,363	259	0.30%	0.42	1.43 [0.60–3.42]
Total	150,611	510	0.34%
Seniority of physicians				0.31c
Junior	11,960	36	0.30%	Reference
Intermediate	52,621	155	0.29%	0.40	0.85 [0.58–1.24]
Senior	86,030	319	0.37%	0.98	0.99 [0.70–1.42]
Total	150,611	510	0.34%
Specialty of physicians				< 0.001c
Ophthalmology and otorhinolaryngology	5615	39	0.69%	Reference
Family planning	13,421	75	0.56%	0.78	1.11 [0.55–2.26]
General surgery	4763	23	0.48%	0.76	0.89 [0.40–1.94]
Pediatrics	55,713	206	0.37%	< 0.001	0.45 [0.32–0.64]
General medicine	3807	13	0.34%	0.34	0.66 [0.28–1.55]
Reproductive medicine	12,634	38	0.30%	0.18	0.60 [0.28–1.27]
Gynecology	33,962	86	0.25%	0.04	0.49 [0.25–0.96]
Obstetrics	16,702	26	0.16%	0.003	0.31 [0.14–0.66]
Dermatology	3994	4	0.10%	< 0.001	0.13 [0.05–0.37]
Total	150,611	510	0.34%
Work day				< 0.001c
Weekends	30,534	72	0.24%	Reference
Weekdays	120,077	438	0.36%	< 0.001	1.65 [1.27–2.14]
Total	150,611	510	0.34%
Workload				0.97c
Low	75,862	268	0.35%	Reference
High	74,749	242	0.32%	0.97	1.00 [0.83–1.19]
Total	150,611	510	0.34%

^a The rates were calculated by no. of prescriptions with errors by total prescriptions in each subgroup

^b The predictor of drug order was not taken into list box of categorical covariates at SPSS

^c Total p value of each predictor from likelihood ratio test