Nonclinical factors associated with primary care physicians' ordering patterns of magnetic resonance imaging/computed tomography for headache

Rationale and Objectives. The purpose of ordering an imaging test for headache, which is one of the most common reasons for patient consultation with a primary care physician (PCP), include medical indications as well as patient anxiety and medico-legal concerns. The impact of nonclinical factors on PCPs' ordering patterns of magnetic resonance imaging/computed tomography for patients presenting with a headache was examined. Materials and Methods. A retrospective record review of all patients treated for headache as their primary complaint by a PCP from a multispecialty group practice associated with an 180,000-member Health Maintenance Organization during calendar year 2000 was examined. The practice included 18 clinics. Logistic regression was used to estimate the association between physician ordering patterns of imaging tests and patient, physician, and clinic setting characteristics. Results. Of the total study subjects (n = 4,372), a magnetic resonance imaging/computed tomography imaging test was ordered for 5.3%. At their first encounter, patient's gender, site of care, and insurance status under the health care system's Health Maintenance Organization had statistically significant associations with the likelihood of imaging test orders. Female physicians were less likely to order an imaging test (OR = 0.65; 95% confidence interval, 0.39-1.08). For subsequent encounters, however, site of care was the only nonclinical factor that had a consistent association with the likelihood of having a magnetic resonance imaging/computed tomography ordered. Conclusion. These data show that a number of nonclinical factors may have been associated with having an imaging test ordered by a PCP when patients presented with a headache. These factors were more significant when the patient was being seen for the first time with this complaint.