Radiological studies are an important component of ambulatory medical costs, and guidelines often focus on their appropriate use. However, little is known about the correlates of the use of those services, particularly the influence of patients' preferences on physicians' utilization decisions.
To study patients presenting for outpatient treatment of respiratory problems and low back pain, and to examine the magnitude of the effect of the patients' perceived need for radiological studies (radiology preference score) on use of those services.
Office practices of generalist physicians in predominantly rural areas of 8 states.
A total of 52 generalist physicians agreed to enroll consecutive Medicare-eligible patients making office visits for respiratory problems or low back pain. Of 1785 eligible patients invited to participate, 132 (7%) refused and 1137 (69%) of 1653 returned questionnaires.
Radiology utilization rates (plain film, computed tomographic scan, or magnetic resonance image scan) were determined by patient self-report. To assess perceived need for radiological studies, we asked patients how necessary they believed an x-ray film was in the evaluation of 4 common complaints (respiratory problems, low back pain, knee pain, and knee swelling). A summary radiology preference score was created from 3 of the 4 items, excluding the item referring to the patients' index complaint.
Six hundred fifteen respiratory and 522 low back pain patients were enrolled; mean ages were 69 and 64 years, respectively. Radiology utilization rates were 37% for respiratory and 26% for low back pain patients. In multiple logistic regression models, for respiratory patients radiology utilization was related significantly to the radiology preference score (odds ratio [OR] for fourth quartile compared with first quartile, 1.94; 95% confidence interval [CI], 1.11-3.37; P = .02), to having a physician who owned radiology equipment (OR, 1.81; 95% CI, 1.23-2.66; P = .002), and current smoking (OR, 1.58; 95% CI, 1.04-2.41; P = .03). For low back pain patients, radiology utilization was significantly related to the radiology preference score (OR for fourth compared with first quartile, 2.55; 95% CI, 1.29-5.06; P = .007), bothersomeness of the pain (OR for fourth compared with first quartile, 3.74; 95% CI, 1.74-8.04; P<.001), and a diagnosis of osteoporosis (OR, 1.67; 95% CI, 1.01-2.75; P = .04).
Patients' perceived need for radiological studies was significantly associated with use of those services for outpatients with respiratory problems and low back pain. These findings suggest that patients communicate their wishes to physicians, either directly or indirectly, regarding services they think are necessary. Differences in physicians' adherence to guidelines regarding radiology utilization may in part reflect variations in patients' perceived need for those services. Efforts to educate patients about when radiological studies are medically indicated may be an important complement to practice guidelines or other utilization-related financial incentives.