Background: Population-based variations in rates of operations for the treatment of lumbar disc herniation and spinal stenosis are well known. This variability may occur in part because of differences in the threshold at which physicians recommend an operation, reflecting uncertainty about the optimum use of an operative procedure. To the best of our knowledge, no previous reports have indicated whether differences in population-based rates of operative treatment are associated with patient outcomes.
Methods: The Maine Lumbar Spine Study is an ongoing prospective study of 655 patients who had a herniated lumbar disc or spinal stenosis. The patients were enrolled by their physicians, who provided baseline demographic and treatment-related data. The patients completed baseline and follow-up questionnaires that focused on symptoms, function, satisfaction, and quality of life. Small-area variation analysis was used to develop three distinct so-called spine service areas in Maine. The outcomes (usually at four years; minimum, two years) were compared among these areas, in which a total of 250 patients had been managed operatively and had answered questionnaires.
Results: Population-based rates of operative treatment derived from statewide data that had been collected over five years in the state of Maine ranged from 38 percent below to 72 percent above the average rate in the state (a greater than fourfold difference). The outcomes for the patients who had been managed by surgeons in the lowest-rate area were superior to those for the patients in the two higher-rate areas. Seventy-nine percent (fifty-seven) of seventy-two patients in the lowest-rate area had marked or complete relief of pain in the lower extremity compared with 60 percent (eighteen) of thirty patients in the highest-rate area. The improvements in the Roland disability score (p < or = 0.01), quality of life (p < or = 0.01), and satisfaction (p < or = 0.05) were significantly greater among the patients in the lowest-rate area. The patients in the higher-rate areas generally had less severe symptoms and findings at baseline than those in the lowest-rate area did.
Conclusions: Higher population-based rates of elective spinal operations may be associated with inferior outcomes. This variability is possibly related to differences in physicians' preferences with regard to recommending an operation and in their criteria for the selection of patients. Physicians cannot assume that their outcomes will be the same as those of others, and therefore they need to evaluate their own results.