In this review we identified five studies comparing surgery with conservative care. Only one low-risk-of-bias study compared early surgery to prolonged conservative care  and demonstrated more relief of leg pain up to 3 months for early surgery, but at 1 year the differences disappeared. The trials of surgery versus usual conservative treatment showed inconsistent findings. One low-risk-of-bias study compared surgery versus conservative treatment  and found no differences between the two treatments. We were unable to perform a meta-analysis of these three studies because of the poor data presented in two of the studies. An observational cohort study conducted alongside one trial included 743 patients that received their preferred treatment. Both groups improved substantially over time, but surgery showed significantly better results for pain and function as compared with conservative treatment .
Three of the five studies found an effect in the early postoperative period, which diminished during further follow-up. This is relevant because a faster recovery rate could, besides the clinical benefit, have an economic advantage in a relatively young patient population. A cost-effectiveness study performed alongside the trial of Peul et al.  showed that surgery is cost-effective with a willingness to pay 40,000 € as per quality-adjusted life years (QALY) . In relation to this, timing of treatment is under debate, but for a reliable analysis of the effect of different timing, information about duration of symptoms is needed. The duration between onset of symptoms and actual treatment is described in four of the five trials [2, 12, 13, 19]. Equally important is the timing of the treatment after diagnosis by protocol or waiting list. This is only reported in two of the trials being 2 weeks [2, 13]. Heterogeneity in the duration of the symptoms or in the timing of treatments introduces a difference in timing of treatment since the onset of complaints and thus bias in the analysis of recovery rate.
The duration and intensity of the conservative treatment is poorly described in the included studies. There are many treatment regimens and modalities available for conservative treatment of sciatica  varying from steroids  to traction  to physiotherapy interventions . Evidence from systematic reviews of conservative interventions for sciatica fail to identify the effect of one intervention over the other, however, large studies with a low risk of bias are scarce . In order to make an informed decision about the clinical homogeneity of the included comparisons, detailed information about the treatments is essential and the denomination “conservative treatment” is not sufficient.
Three narrative reviews which examined choice of surgery or conservative care concluded that surgery is indicated in presence of persistent neuromotor deficit [1, 7, 9]. Both Awad and Moskovich  and Legrand et al.  suggested to let the patient make an informed choice. The review of Awad and Moskovich  was published before publication of three of the studies included in this review [12, 13, 22]. Although the publication of Legrand et al. was in 2007, this study did not include two studies [2, 12] published before that date. Gregory et al.  promoted surgery with persistent neuromotor deficit or severe sciatica with a positive straight-leg-raise test and imaging demonstrating lumbar disc herniation at the nerve root level correlating with the patient’s examination findings. Although published in October 2008, this study did not include three studies [2, 12, 19] published before that date. Both reviews did not describe their search strategy, selection methods or quality assessments of the included studies and are therefore, potentially, prone to bias.
Strengths and limitations
There are some limitations in our present review. Firstly, the limited amount of studies, especially those with a low risk of bias, limits the strength of our recommendations. The GRADE approach needs consistent findings in separate studies to raise the level of evidence to ‘moderate’ or ‘high’. The overall quality of the evidence should not be misinterpreted as the quality of an individual study.
A more general problem lies within the methodology of research for the assessment of timing of interventions. Current research models, with the randomised clinical trial as the gold standard, do not allow for a proper analysis of the difference between the time from inclusion (or onset of symptoms) to intervention and prolonged control intervention. The design and analysis of studies is complicated by the difference in cross-over possibilities between the two interventions. Crossing over from conservative treatment to surgery is to be expected for a certain amount of patients. The reverse is also possible as shown in the study of Weinstein et al. . The mechanism is however different as crossing over is only counted as surgery did not take place at all.
The clinical data seem to favour surgery slightly; however, the costs of surgery are likely to be higher than conservative treatment for patients or the health care system. Also, potential complications are probably more prevalent and more severe with surgery. Only from a societal perspective it might be more cost-effective because of lower cost of production loss . Evaluating conservative treatment and surgical intervention requires a different set of outcome parameters, including complications, re-surgeries and economical information to allow for a balanced and informed cost-complication-effectiveness decision.