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Methods
Literature Search
PubMed, Embase and The Cochrane Neuromuscular Disease Group Trials Specialized Register were searched from January 1990 to December 2012 inclusive for published articles on 'chronic inflammatory demyelinating polyradiculoneuropathy' and 'treatment'. Medical subject heading (MeSH) search terms were used to search PubMed and a keyword search were used if required. Keyword search terms used were; "chronic inflammatory demyelinating polyneuropathy" or "CIDP" or "chronic inflammatory polyneuropathy" or "autoimmune neuropathies" combined with "drug therapy" or "treatment" or "therapy" or "randomised control trial" or "clinical trial". Included in this study were double blind randomised controlled trials for treating CIDP. All current and emerging treatments for CIDP were included in the study and papers were excluded if the diagnosis of CIDP was considered secondary to an underlying disorder.
Study Selection and Participants
When journal articles did not publish the necessary data for the analyses, attempts were made to contact the authors. This study included adult patients of both sexes diagnosed with CIDP according to the criteria for diagnosis; clinically accepted electrodiagnostic criteria, progression of weakness lasting more than eight weeks and increased cerebrospinal fluid protein. However there are numerous sets of accepted criteria for the diagnosis of CIDP, with many variables and there is not one uniform set of criteria. Papers were excluded if subjects had another systemic disease, family history of CIDP or drug or toxin exposure known to cause CIDP. No restrictions were set on suitable settings for involvement in this review.
Assessment of Methodological Quality
Studies used in the systematic review were assessed for levels of concealment of allocation at randomisation and internal validity to determine if any bias was present. Quality of evidence for each study was graded from very low to high using GRADEprofiler (http://ims.cochrane.org/gradepro). Each paper was assessed for risk of bias, inconsistency, indirectness, imprecision, publication bias, large effect, plausible confounding would change the effect and dose–response gradient. Each item was graded as either; No- negligible, Level 1- Serious or Level 2- Very Serious. GRADEprofiler software utilised these parameters to report a summarised measure of the quality of evidence from; very low, low, moderate to high (Table 1).
Statistical Analysis
For the nine randomised controlled trials in this analysis, the proportion of patients with significant improvement in disability or the proportion that exhibited adverse effects for the treatment were used to calculate the odds ratio and 95% confidence intervals for each study. Assumed and corresponding risks (95% confidence interval) were calculated using GRADEprofiler Version 3.6 software. A summary of findings was also created using GRADEprofiler software. Meta-analysis was performed using OpenMetaAnalyst open-source software (http://www.cebm.brown.edu/open_meta) on eight of the nine randomised controlled trials. The study by the RMC Trial Group titled "Randomised controlled trial of methotrexate for chronic inflammatory demyelinating polyradiculoneuropathy (RMC trial): a pilot, multicentre study", did not fit the inclusion criteria for meta-analysis as the outcome measure was a reduction in the weekly dose of IVIg whereas the other studies measured response to the therapies. To assess overall efficacy from all the studies, we calculated odds ratio, and used a binary random-effects model to report an overall effect, heterogeneity and p-value together with 95% CI. Statistical significance was declared if the p value was <0.05. Weighting for each study was also reported (Figure 1).
(Enlarge Image)
Figure 1.
Meta-analysis of studies to improve recovery of CIDP versus control groups. Odds ratios are presented with 95 percent confidence intervals. Overall effect is shown using DerSimonian-Laird (DL) binary random- effect model.
Data Extraction
Titles and abstracts selected were checked by the first author who also determined which studies fit the inclusion criteria. In view of the fact that different studies used different disability scales, the primary outcome measure was defined as the proportion of patients with a clinical response during or after treatment. The strictest criteria to define improvement were used in each study.
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