Table 3.

Linear Regression Evaluating PCP Characteristics Associated with E-Prescribing Usage (n = 241)^*

PCP Characteristics	Variable Estimate	95% CI	P Value**
Practice Size†			0.02
2–5 physicians	−0.01	−0.09 – 0.07	0.76
6–10 physicians	−0.08	−0.21 – 0.04	0.17
>10 physicians	−0.18	−0.31 – −0.05	0.01

^*By dividing the number of electronic prescriptions written for Horizon BCBSNJ patients during the e-prescribing usage evaluation period (1/1/06 – 6/30/06) by the number of Horizon BCBSNJ pharmacy claims processed during the e-prescribing usage evaluation period, an ‘e-prescribing usage ratio’ ranging from 0–1 is calculated for each physician. This ‘eRx use index’ is the dependent variable for this regression model, which uses data from 241 physicians in the e-prescribing cohort. Fifty-six physicians are excluded from this analysis because they never used the system after it was installed (n = 34) or because they quit using it after some initial usage (n = 22).

^**PCP characteristics with no association (not used as predictors in this model) are PCP specialty and PCP pharmaceutical claim volume; PCP patient panel age, gender, income, and neighborhood racial and ethnic makeup. R2 = 0.01

^†Referent practice size is 1 physician.