STUDY DESIGN Prospective observational cohort.   
 OBJECTIVE To describe the baseline characteristics of patients with a diagnosis of intervertebral disc herniation who had different treatment preferences and the relationship of specific expectations with those preferences.    SUMMARY OF BACKGROUND DATA Data were gathered from the observational cohort of the Spine Patient Outcomes Research Trial (SPORT). Patients in the observational cohort met eligibility requirements identical to those of the randomized cohort, but declined randomization, receiving instead the treatment of their choice.   
 METHODS Baseline preference and expectation data were acquired at the time of enrollment of the patient, before exposure to the informed consent process. Univariate analyses were performed using a t test for continuous variables and chi for categorical variables. Multivariate analyses were also performed with ANCOVA for continuous variables and logistic regression for categorical variables. Multiple logistic regression models were developed in a forward stepwise fashion using blocks of variables.   
 RESULTS More patients preferred operative care: 67% preferred surgery, 28% preferred nonoperative treatment, and 6% were unsure; 53% of those preferring surgery stated a definite preference, whereas only 18% of those preferring nonoperative care had a definite preference. Patients preferring surgery were younger, had lower levels of education, and higher levels of unemployment/disability. This group also reported higher pain, worse physical and mental functioning, more back pain related disability, a longer duration of symptoms, and more opiate use. Gender, race, comorbidities, and use of other therapies did not differ significantly across preference groups. Patients' expectations regarding improvement with nonoperative care was the strongest predictor of preference.   
 CONCLUSION Patient expectations, particularly regarding the benefit of nonoperative treatment, are the primary determinant of surgery preference among patients with lumbar intervertebral disc herniation. Demographic, functional status, and prior treatment experience had significant associations with patients' expectations and preferences.
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