Table 3.

Results of Logistic Regression Estimating Likelihood of Employing NPs and PAs

Characteristic	Odds Ratio	95% CI
Physician
Specialty
Surgical oncology	—	—
Medical oncology	2.63	1.73 to 3.99
Radiation oncology	0.90	0.50 to 1.62
Sex
Female	1.11	0.67 to 1.87
Male
Geographical location
Metropolitan Detroit
Los Angeles County	1.39	0.91 to 2.10
Time in practice, years
≤ 10	1.94	1.18 to 3.16
10-20	1.61	1.00 to 2.60
> 20 yr	—	—
Breast cancer specialization, % of all cases
< 25	0.48	0.25 to 0.92
25-50	0.57	0.30 to 1.09
> 50	—	—
Practice
University affiliation
Yes	2.20	1.44 to 3..37
No	—	—
No. of physicians in the practice
< 3	0.14	0.09 to 0.24
3-5	0.37	0.23 to 0.60
≥ 6	—	—

NOTE: Dashes indicate reference category in the logistic regression model.

Abbreviations: NPs, nurse practitioners; PAs, physician assistants.