Overall, 1,244 SPORT participants with lumbar intervertebral disc herniation were enrolled (501 in the randomized cohort, and 743 in the observational cohort). () In the randomized cohort, 245 were assigned to surgical treatment and 256 to non-operative treatment. Of those randomized to surgery, 57% had surgery by 1 year and 59% by 4 years. In the group randomized to non-operative care, 41% of patients received surgery by 1 year and 45% received surgery by 4 years. In the observational cohort, 521 patients initially chose surgery and 222 patients initially chose non-operative care. Of those initially choosing surgery, 95% received surgery by 1 year; at 4 years no further surgeries had been reported. Of those choosing non-operative treatment, 20% had surgery by 1 year, 24% by 4 years. In both cohorts combined, 805 patients received surgery at some point during the first 4 years; 439 (35%) remained non-operative. Over the 4 years, 1,192 (96%) of the original enrollees completed at least 1 follow-up visit and were included in the analysis (randomized cohort: 94% and observational cohort 97%); between 65% and 87% of enrollees supplied data at each follow-up interval with losses due to dropouts, missed visits, or deaths ().
Exclusion, Enrollment, Randomization and Follow-up of Trial Participants
Baseline characteristics are compared in . Overall, the cohorts were similar. However, patients in the observational cohort had more disability, a strong preference for surgery, more often rated their problem as worsening, and were slightly more likely to have a sensory deficit.
Patient baseline demographic characteristics, comorbidities, and health status measures according to study cohort and treatment received.
Summary statistics for the combined cohorts are also displayed in according to treatment received. The study population had an overall mean age of 41.7 with a mean of 40.7 in the surgery group and a mean of 43.9 in the non-operative group. There were slightly more men than women. Subjects receiving surgery were: younger; less likely to be working; more likely to report being disabled and to be receiving compensation; had slightly greater BMI’s; fewer joint and other co-morbidities; more pain; frequent and bothersome sciatica; depression; dissatisfaction with their symptoms and more often rated them as getting worse; less function; and were more likely to prefer surgery. Subjects receiving surgery also had more ipsilateral and contralateral straight leg tests, and more neurologic, sensory, and motor deficits. Radiographically, their herniations were more likely to be at the L4–5 and L5-S1 levels and to be posterolateral in location.
Non-operative treatments within 4 years of enrollment were similar between the two cohorts. However, more observational patients reported visits to other practitioners (57% observational vs. 37% randomized, p = <0.001); and randomized patients had more (randomized vs. observational): injections (57% vs. 40%, p= <0.001), activity restriction (32% vs. 20% p=0.004) and narcotics (50% vs. 37% p=0.005).
Surgical Treatment and Complications
Overall surgical treatment and complications were similar between the two cohorts (). The average surgical time was slightly longer in the randomized cohort (80.6 minutes randomized vs. 74.9 minutes observational, p=0.049). Median (interquartile range) values for surgical time were 74.5 minutes (57.8, 90.0) for the randomized and 70 minutes (50.0, 90.0) for the observational cohort. The average blood loss was 67.5cc in the randomized cohort vs. 63.0cc in the observational, p=0.56. Median (25th percentile, 75th percentile) for blood loss was 50cc (25, 75) in the randomized cohort and 50cc (25, 50) in the observational. Only 6 patients total required intra-operative transfusions. There were no perioperative mortalities. The most common surgical complication was dural tear (3% of cases). Re-operation occurred in a combined 6% of cases by 1 year, 8% at 2 years, 9% at 3 years, and 10% at 4 years post surgery. The rates of reoperation were not significantly different between the randomized and observational cohorts. Seventy-five of the 81 re-operations noted the type of re-operation; approximately 50% of these (48/75) were listed as recurrent herniations at the same level. One death occurred within 90 days post-surgery related to heart surgery at another institution; the death was judged to be unrelated and was reported to the Institutional Review Board and the Data and Safety Monitoring Board.
Operative treatments, complications and events.
Non-adherence to treatment assignment affected both treatment arms: patients chose to delay or decline surgery in the surgical arm and crossed over to surgery in the non-operative arm. () Some characteristics of crossover patients were statistically different from patients who did not cross over (). Patients crossing over to non-operative care were older, had higher incomes and less pain and disability, were less likely to have an ipsilateral straight leg raise and to perceive their symptoms as getting worse, more likely to have a high level disc herniation and to express a baseline preference for non-operative care, and were less dissatisfied with their symptoms, Patients crossing over to surgery within 4 years had lower income, worse physical function and more self-rated disability, were more dissatisfied with their symptoms, perceived they were getting worse and expressed a baseline preference for surgery. While more patients crossed from non-operative treatment to surgery [112 (24%)] than crossed from surgery to nonoperative treatment [89 (19%)], this difference is not significant based on a McNemar’s test (p=0.12).
Statistically significant predictors of adherence to treatment among RCT patients.
Main Treatment effects
In the intent-to-treat analysis of the randomized cohort, all measures over 4 years favored surgery but there were no statistically significant treatment effects in any of the primary outcome measures at any time interval ( and ). The secondary outcomes (sciatica bothersomeness index and self-rated improvement) were statistically significant in favor of surgery in the intent-to-treat analysis at 1 year;4
significance was maintained out to 4 years only for the sciatica bothersomeness index ( and ).
Primary analysis results for years 3 and 4. Intent-to-treat for the randomized cohort and adjusted* analyses according to treatment received for the randomized and observational cohorts combined.‡‡
Primary Outcomes (SF-36 Bodily Pain and Physical Function, and Oswestry Disability Index) in the Randomized and Observational Cohorts during 2 Years of Follow-up
Secondary Outcomes in the Randomized and Observational Cohorts during 2 Years of Follow-up
The global hypothesis test (not shown) comparing the as-treated treatment effects between the randomized and observational cohorts over all time periods showed no difference between the randomized and observational cohorts (p = 0.44 for SF-36 BP, p = 0.76 for SF-36 PF, and p= 0.90 for the ODI). Treatment effects for the primary outcomes in the combined as-treated analysis were significant at 2 years and maintained out to 4 years: SF-36 BP 15.0 p<0.001 (95% CI 11.8 to 18.1); SF-36 PF 14.9 p<0.001 (95% CI 12.0 to 17.8); ODI -13.2 p<0.001 (95% CI −15.6 to −10.9. () The footnote for describes the controlling covariates for the final model.
Results from the intent-to-treat and as-treated analyses of the two cohorts are compared in . The as-treated treatment effects significantly favored surgery in both cohorts. In the combined analysis, treatment effects were statistically significant in favor of surgery for all primary and secondary outcome measures (with the exception of work status) at each time point ( and ).
The treatment effects for the secondary measures of sciatica bothersomeness, satisfaction, and self-rated improvement narrowed between 3 months and 2 years but remained significant at all periods. Work status was significantly worse in the surgery group at 3 months due to surgery patients recovering from surgery; work status thereafter showed a small but non-significant benefit for surgery. At 4 years, the adjusted percentage of patients working was 84.4% surgical vs. 78.4% non-operative, treatment effect 6.0 (95% CI −0.9, 12.9). ( and )