Both operated and nonoperated patients with intervertebral disk herniation improved substantially over a 2-year period. The intent-to-treat analysis in this trial showed no statistically significant treatment effects for the primary outcomes; the secondary measures of sciatica severity and self-reported progress did show statistically significant advantages for surgery. These results must be viewed in the context of the substantial rates of nonadherence to assigned treatment. The pattern of nonadherence is striking because, unlike many surgical studies, both the surgical and nonoperative treatment groups were affected.35
The most comparable previous trial8
had 26% crossover into surgery at 1 year, but only 2% crossover out of surgery. The mixing of treatments due to crossover can be expected to create a bias toward the null.34
The large effects seen in the as-treated analysis and the characteristics of the crossover patients suggest that the intent-to-treat analysis underestimates the true effect of surgery.
SPORT findings are consistent with clinical experience in that relief of leg pain was the most striking and consistent improvement with surgery. Importantly, all patients in this trial had leg pain with physical examination and imaging findings that confirmed a disk herniation. There was little evidence of harm from either treatment. No patients in either group developed cauda equina syndrome; 95% of surgical patients had no intraoperative complications. The most common complication, dural tear, occurred in 4% of patients, similar to the 2% to 7% noted in the meta-analysis by Hoffman et al,7
2.2% seen in the MLSS,29
and 4% in the recent series from Stanford.36
One limitation is the potential lack of representativeness of patients agreeing to be randomized to surgery or nonoperative care; however, the characteristics of patients agreeing to participate in SPORT were very similar to those in other studies.29,36
The mean age of 42 years was similar to the mean ages in the MLSS,29
the series of Spangfort,37
and the randomized trial by Weber,8
and only slightly older than those in the recent series from Stanford (37.5 years).36
The proportion of patients receiving workers' compensation in SPORT (16%) was similar to the proportion in the Stanford population (19%) but lower than that in the MLSS population (35%), which specifically oversampled patients receiving compensation. Baseline functional status was also similar, with a mean baseline ODI of 46.9 in SPORT vs 47.2 in the Stanford series, and a mean baseline SF-36 physical function score of 39 in SPORT vs 37 in the MLSS.
The strict eligibility criteria, however, may limit the generalizability of these results. Patients unable to tolerate symptoms for 6 weeks and demanding earlier surgical intervention were not included, nor were patients without clear signs and symptoms of radiculopathy with confirmatory imaging. We can draw no conclusions regarding the efficacy of surgery in these other groups. However, our entry criteria followed published guidelines for patient selection for elective diskectomy, and our results should apply to the majority of patients facing a surgical decision.38,39
To fully understand the treatment effect of surgery compared with nonoperative treatment, it is worth noting how each group fared. The improvements with surgery in SPORT were similar to those of prior series at 1 year: for the ODI, 31 points vs 34 points in the Stanford series; for the bodily pain scale, 40 points vs 44 in the MLSS; and for sciatica bothersomeness, 10 points vs 11 in the MLSS. Similarly, Weber8
reported 66% “good” results in the surgery group, compared with the 76% reporting “major improvement” and 65% satisfied with their symptoms in SPORT.
The observed improvements with nonoperative treatment in SPORT were greater than those in the MLSS, resulting in the small estimated treatment effect. The nonoperative improvement of 37, 35, and 9 points in bodily pain, physical function, and sciatica bothersomeness, respectively, were much greater than the improvements of 20, 18, and 3 points reported in the MLSS. The greater improvement with nonoperative treatment in SPORT may be related to the large proportion of patients (43%) who underwent surgery in this group.
The major limitation of SPORT is the degree of nonadherence with randomized treatment. Given this degree of crossover, it is unlikely that the intent-to-treat analysis can form the basis of a valid estimate of the true treatment effect of surgery. The “as-treated” analysis with adjustments for possible confounders showed much larger effects in favor of surgical treatment. However, this approach does not have the strong protection against confounding that is afforded by randomization. We cannot exclude the possibility that baseline differences between the as-treated groups, or the selective choice of some but not other patients to cross over into surgery, may have affected these results, even after controlling for important covariates. Due to practical and ethical constraints, this study was not masked through the use of sham procedures. Therefore, any improvements seen with surgery may include some degree of “placebo effect.”
Another potential limitation is that the choice of nonoperative treatments was at the discretion of the treating physician and patient. However, given the limited evidence regarding efficacy for most nonoperative treatments for lumbar disk herniation and individual variability in response, creating a limited, fixed protocol for nonoperative treatment was neither clinically feasible nor generalizable. The nonoperative treatments used were consistent with published guidelines.17,38,39
Compared with the MLSS, SPORT had lower use of activity restriction, spinal manipulation, transcutaneous electrical nerve stimulation, and braces and corsets, and higher rates of epidural steroid injections and use of narcotic analgesics. This flexible nonoperative protocol had the advantages of individualization that considered patient preferences in the choice of nonoperative treatment and of reflecting current practice among multidisciplinary spine practices. However, we cannot make any conclusion regarding the effect of surgery vs any specific nonoperative treatment. Similarly, we cannot adequately assess the relative efficacy of any differences in surgical technique.