Table 3.

Rates of errors

	N			Rates per 100 prescriptions (95% CI)*
	Total	NY	MA	Total	NY	MA	p Value†
	9385	5873	3512	–	–	–
Rule violations	5103	3463	1640	54.4 (46.8 to 63.2)	59.0 (49.2 to 70.7)	46.7 (36.5 to 59.8)	0.13
Prescribing errors	19 956	11 043	8913	212.6 (186.2 to 243.0)	188.0 (155.7 to 227.3)	253.8 (215.1 to 299.5)	0.01
Prescribing errors excluding illegibility errors	3443	2007	1436	36.7 (30.7 to 44.0)	34.1 (29.6 to 39.5)	40.9 (28.0 to 58.8)	0.39
Near misses	142	94	48	1.5 (1.2 to 1.9)	1.6 (1.2 to 2.2)	1.4 (0.9 to 2.0)	0.77
Near misses excluding illegibility errors	104	65	39	1.1 (0.9 to 1.4)	1.1 (0.8 to 1.5)	1.1 (0.7 to 1.6)	0.80
ADE	14	1	13	0.15 (0.07 to 0.31)	0.02 (0.002 to 0.12)	0.37 (0.18 to 0.76)	0.004

^*Clustered adjusted Poisson 95% CI.

^†Poisson regression adjusting for clustering comparing rates for NY and MA.

ADE, adverse drug event; CDS, clinical decision support; MA, Massachusetts; NY, New York.