Validity of outcome measures used in randomized clinical trials and observational studies in degenerative lumbar spinal stenosis.

It is unclear whether outcome measures used in degenerative lumbar spinal stenosis (DLSS) have been validated for this condition. Cross-sectional analysis of studies for DLSS included in systematic reviews (SA) and meta-analyses (MA) indexed in the Cochrane Library. We extracted all outcome measures for pain and disability. We assessed whether the studies provided external references for the validity of the outcome measures and the quality of the validation studies. Out of 20 SA/MA, 95 primary studies used 242 outcome measures for pain and/or disability. Most commonly used were the VAS (n = 69), the Oswestry Disability Index (n = 53) and the Zurich Claudication Questionnaire (n = 22). Although validation references were provided in 45 (47.3%) primary studies, only 14 validation studies for 9 measures (disability n = 7, pain and disability combined n = 2) were specifically validated in a DLSS population. The quality of the validation studies was mainly poor. The Zurich Claudication Questionnaire was the only disease specific tool with adequate validation for assessing treatment response in DLSS. To compare results from clinical studies, outcome measures need to be validated in a disease specific population. The quality of validation studies need to be improved and the validity in studies adequately cited.

Association between depression and anxiety on symptom and function after surgery for lumbar spinal stenosis.

Evidence on the role of depression and anxiety in patients undergoing surgical treatment for symptomatic degenerative lumbar spinal stenosis (DLSS) is conflicting. We aimed to assess the association between depression and anxiety with symptoms and function in patients undergoing surgery for DLSS. Included were patients with symptomatic DLSS participating in a prospective multicentre cohort study who underwent surgery and completed the 24-month follow-up. We used the hospital anxiety and depression scale (HADS) to assess depression/anxiety. We used mixed-effects models to quantify the impact on the primary outcome change in the spinal stenosis measure (SSM) symptoms/function subscale from baseline to 12- and 24-months. Logistic regression analysis was used to quantify the odds of the SSM to reach a minimal clinically important difference (MCID) at 24 months follow-up. The robustness of the results in the presence of unmeasured confounding was quantified using a benchmarking method based on a multiple linear model. Out of 401 patients 72 (17.95%) were depressed and 80 anxious (19.05%). Depression was associated with more symptoms (ß = 0.36, 95% confidence interval (CI) 0.20 to 0.51, p < 0.001) and worse function (ß = 0.37, 95% CI 0.24 to 0.50, p < 0.001) at 12- and 24-months. Only the association between baseline depression and SSM symptoms/function was robust at 12 and 24 months. There was no evidence for baseline depression/anxiety decreasing odds for a MCID in SSM symptoms and function over time. In patients undergoing surgery for symptomatic DLSS, preoperative depression but not anxiety was associated with more severe symptoms and disability at 12 and 24 months.

[Pain medications for acute and chronic low back pain]. / Medikamentöse Therapie bei akuten und chronischen lumbalen Rückenschmerzen.

Low back pain is common. In the acute (duration <6 weeks) and subacute pain phases (6-12 weeks) the main goal of pharmacological pain treatment is to enable patients to move and to stay as active as possible. In the chronic phase, pain medications can support non-pharmacological measures and improve physical function. Although almost every person will experience low back pain at least once in a lifetime, for many pain medications no clinical studies on their efficacy exist. Most data are available on the efficacy of non-steroidal anti-inflammatory drugs (NSAIDs) in acute and chronic low back pain; however, potential adverse effects and contraindications for NSAIDs need to be taken into account when the medication is prescribed. For other non-opioid medications (e. g. paracetamol, metamizole) the efficacy is not well studied. Weak and strong opioids have been shown to be effective compared to placebo in the short term; however, there is increasing evidence that opioids are no more effective than non-opioid medications in the treatment of acute and chronic low back pain. Furthermore, gastrointestinal and central nervous system adverse effects of opioids should be considered. Conclusion: in low back pain, the choice of a specific pain medications is based on the individual patient preferences, contraindications, and potential adverse effects. The main goal of pain medications is to enable patients to stay active. In persisting pain, non-pharmacological measures are important and should complement pharmacological pain treatment.

Cost-effectiveness of conservative versus surgical treatment strategies of lumbar spinal stenosis in the Swiss setting: analysis of the prospective multicenter Lumbar Stenosis Outcome Study (LSOS).

PURPOSE: To evaluate the cost-effectiveness of conservative versus surgical treatment strategies for lumbar spinal stenosis (LSS). METHODS: Patients prospectively enrolled in the multicenter Lumbar Stenosis Outcome Study (LSOS) with a minimum follow-up of 12 months were included. Quality adjusted life years (QALY) were calculated based on EQ-5D data. Cost data were retrieved retrospectively. Cost-effectiveness was calculated via decision tree analysis. RESULTS: A total of 434 patients were included, treated surgically (n = 170) or conservatively (n = 264) for LSS. The majority of surgically treated patients underwent decompression (n = 141, 82.9%), and 17.1% (n = 29) additionally underwent fusion. A reoperation was required in 13 (7.6%) surgically treated patients. In 27 (10.2%) conservatively treated patients, a single infiltration was successful, with no further infiltration or surgery within the follow-up. However, 46 patients (17.4%) required multiple infiltrations, and in 191 (72.4%) initially conservatively treated patients a subsequent surgery was needed. The area under the curve was 0.776 QALY in the surgical arm (0.776 and 0.790, decompression or additional fusion, respectively), compared to 0.778 in the conservative arm. Treatment costs were estimated at CHF 12,958 and 13,637 (USD 13,465 and 14,169) in surgically and initially conservatively treated patients, respectively [base-case incremental cost-effectiveness ratio (ICER): CHF 392,145, USD 407,831], per QALY gained. Probabilistic sensitivity analysis identified surgery as the preferred strategy in 67.1%. CONCLUSIONS: Both the surgical and the conservative treatment approach resulted in a comparable health-related quality of life within the first year after study inclusion. Due to slightly higher costs, mostly because the majority of initially conservatively treated patients underwent multiple infiltrations or a subsequent surgery, decompressive surgery was identified as the most cost-effective approach for LSS in this setting.

A novel use of the Spine Tango registry to evaluate selection bias in patient recruitment into clinical studies: an analysis of patients participating in the Lumbar Spinal Stenosis Outcome Study (LSOS).

PURPOSE: Patients enrolled in clinical studies typically represent a sub-set of all who are eligible, and selection bias may compromise the generalizability of the findings. Using Registry data, we evaluated whether surgical patients recruited by one of the referring centres into the Lumbar Spinal Stenosis Outcome Study (LSOS; a large-scale, multicentre prospective observational study to determine the probability of clinical benefit after surgery) differed in any significant way from those who were eligible but not enrolled. METHODS: Data were extracted for all patients with lumbar spinal stenosis registered in our in-house database (interfaced to Eurospine's Spine Tango Registry) from 2011 to 2013. Patient records and imaging were evaluated in relation to the admission criteria for LSOS to identify those who would have been eligible for participation but were not enrolled (non-LSOS). The Tango surgery data and Core Outcome Measures Index (COMI) data at baseline and 3 and 12 months after surgery were analysed to evaluate the factors associated with LSOS enrolment or not. RESULTS: 514 potentially eligible patients were identified, of which 94 (18%) were enrolled into LSOS (range 2-48% for the 6 spine surgeons involved in recruiting patients) and 420 (82%) were not; the vast majority of the latter were due to non-referral to the study by the surgeon, with only 5% actually refusing participation. There was no significant difference in gender, age, BMI, smoking status, or ASA score between the two groups (p ≥ 0.18). Baseline COMI was significantly (p = 0.002) worse in the non-LSOS group (7.4 ± 1.9) than the LSOS group (6.7 ± 1.9). There were no significant group differences in any Tango surgery parameters (additional spine patholothegies, operation time, blood loss, complications, etc.) although significantly more patients in the non-LSOS group had a fusion procedure (38 vs 18% in LSOS; p = 0.0004). Postoperatively, neither the COMI nor its subdomain scores differed significantly between the groups (p > 0.05). Multiple logistic regression revealed that worse baseline COMI (p = 0.021), surgeon (p = 0.003), and having fusion (p = 0.014) predicted non-enrolment in LSOS. CONCLUSION: A high proportion of eligible patients were not enrolled in the study. Non-enrolment was explained in part by the specific surgeon, worse baseline COMI status, and having a fusion. The findings may reflect a tendency of the referring surgeon not to overburden more disabled patients and those undergoing more extensive surgery with the commitments of a study. Beyond these factors, non-enrolment appeared to be somewhat arbitrary, and was likely related to surgeon forgetfulness, time constraints, and administrative errors. Researchers should be aware of potential selection bias in their clinical studies, measure it (where possible) and discuss its implications for the interpretation of the study's findings.

The Effect of Epidural Steroid Injection on Postoperative Outcome in Patients From the Lumbar Spinal Stenosis Outcome Study.

STUDY DESIGN: Retrospective analysis of data from patients participating in the Lumbar Spinal Stenosis Outcome Study (LSOS). OBJECTIVE: The aim of LSOS was to assess clinical outcomes after surgical or nonoperative treatment in patients with and without prior epidural steroid injections. SUMMARY OF BACKGROUND DATA: Epidural steroid injections (ESI), a common treatment modality, reduce symptoms in the short-term, but according to a subgroup analysis from the Spine Patient Outcomes Research Trial (SPORT) they reduce the amount of improvement after subsequent surgical or nonoperative treatment. METHODS: The data of 281 patients with lumbar spinal stenosis who had completed baseline and 6-month follow-up assessments were analyzed. Patients completed the Spinal Stenosis Measure (SSM). Changes in the SSM scores from baseline to follow-up were compared between patients with and without prior ESI, for the surgical and nonsurgical treatment groups. RESULTS: The mean (SD) age of the patients was 75 (8.7) years. 229 patients underwent surgery and 111 of these had received an ESI in the 12 months before surgery. Of the 52 patients treated nonoperatively, 29 had received a prior ESI. The unadjusted changes (improvement) in the SSM-symptom scores between baseline and 6 months' follow up were: surgery and prior ESI 0.95, surgery and no prior ESI 0.78 (P = 0.15); no surgery and prior ESI 0.28, no surgery and no prior ESI 0.29 (P = 0.85). When adjusted for confounding factors, the reduction in SSM-symptom score was greater for surgery than for nonoperative treatment by 0.41 points (P < 0.001); the effect of having had an ESI prior to study entry was -0.08 (P = 0.40). CONCLUSION: The analysis of outcomes in the LSOS cohort provided no evidence that ESIs have a negative effect on the short-term outcome of surgery or nonoperative treatment in patients with lumbar spinal stenosis. LEVEL OF EVIDENCE: 3.