Evidence Synthesis in Mechanical Low Back Pain Rehabilitation Interventions: translate research into practice

AIMS The aim of this dissertation was to evaluate mechanical LBP rehabilitation interventions based on randomized controlled trials (RCTs). In particular, the following part were investigated: the reporting of important aspects of an intervention, the clinical relevance of an intervention and the synthesis of the evidence through multiple interventions treatments. METHODS To assess reporting of different components of study design and assess the clinical relevance in RCTs, a systematic search for all RCTs included in Cochrane systematic reviews (SRs) on LBP published in The Cochrane Database of Systematic Reviews was performed. The description of sample size, interventions, outcomes, and clinical relevance of each RCT was evaluated, independently by two of the investigators, using dedicate extraction forms. To assess the clinical relevance in MA, a Cochrane review focusing on multidisciplinary biopsychosocial rehabilitation (MBR) in short, medium and long terms was selected as a case-study: we re-analysed the data using a MID (minimal important difference) units approach and discussed the implications of this approach compared to the traditional one. Results were expressed in MID units and gave a clinical meaningful interpretation. To estimate the best efficacious intervention, a NMA was implemented using random-effects models within a frequentist setting assuming equal heterogeneity across all comparisons and all ranking probabilities for each treatment outcome in acute LBP interventions as case study were estimated. RESULTS To appraise reporting quality, 185 eligible RCTs from all Cochrane SRs focused on LBP rehabilitation interventions were found. All items necessary for a full replication of the intervention were present only in 33 RCTs (17.8%). Thirty-six different outcomes were investigated across all RCTs. The 2 most commonly reported outcomes were pain (n= 165 RCTs; 89.2%) and disability (n= 118 RCTs; 63.8%). Pain and disability outcomes were found replicable in only 10.3% (n= 17) and 10.2% (n= 12) of the RCTs, respectively. Of the 80 RCTs reporting sample size calculation, only thirteen (16.3%) gave an adequate description of the a priori sample size calculation. We then identified 42 RCTs (41,6%) having both a sample size calculation and a planned MID. Overall, we found that more than one-third of RCTs (37,5%, n=15) were both statistically and clinically significant whereas few (23,8 %, n=10) were statistically significant but not clinically relevant. For the clinical interpretation of MAs we used the MID units approach. In terms of clinical relevance, MBR improved back pain in an appreciable number of patients only at short term (MID lower than but close to 1) whereas in longer time MBR showed little or no effect for the majority of patients (MID close to 0). For multiple comparisons, a NMA was performed on acute and subacute LBP discovering that the best efficacious treatments for pain at short term of follow-up (FU) are muscle relaxant drugs (34.5% probability to be the first treatment) and manual therapy (18.8% probability to be the first treatment). Inconsistency was not found in the network. CONCLUSIONS Despite the remarkable amount of resources spent performing RCTs in the LBP rehabilitation field, the majority of RCTs failed to report sufficient information for sample size, interventions, outcomes and clinical relevance. Moreover, almost a quarter of trials are statistically significant but not clinically significant. Improving the quality of reporting and introducing interpretation of effects in terms of clinical relevance can increase validity and efficacy of research findings, promoting the knowledge translation (KT) of valid results into rehabilitation practices. Only in this light NMA can be used for clinical decision making, based on a strong evidence and a useful tool, for all stakeholders of LBP condition.