Indirect comparison refers to a comparison of different healthcare interventions using data from separate studies, and is often used because of a lack of, or insufficient evidence from head-to-head comparative trials. We aimed to summarize the definition, fundamental theory, type, relevant statistical contents, and to clarify some question on how to use indirect comparison, in order to attract more researchers' attention and promote methodological development of indirect comparison.
ObjectiveTo investigate the effectivness of the clinging lesser trochanter osteotomy with the Wagner cone in total hip arthroplasty (THA) for Crowe type ⅠV developmental dysplasia of the hip (DDH) in adult. MethodsBetween November 2009 and September 2012, 7 female patients (9 hips) with Crowe type ⅠV DDH were treated by THA procedures of clinging lesser trochanter osteotomy with Wagner cone, aged 24-62 years (mean, 42 years). All patients experienced severe pain and claudication. The left hip was involved in 2 cases, the right hip in 3 cases, and bilateral hips in 2 cases. The Harris score of involved hip was 50.00±7.04. The both limps were discrepancy with an average length difference of 3.4 cm (range, 3-4 cm). The results of Trendelenburg sign were positive. X-ray films showed high complete dislocation of the involved hips. ResultsThe incisions healed by first intention. There was no complication such as infection, dislocation, prosthesis loosening, neurovascular injury. The average follow-up was 36.4 months (range, 25-48 months). Pain and claudication were improved and all patients could restore to work. The Harris score was improved to 83.42±6.47, showing significant difference when compared with preoperative score (t=8.90, P=0.00). The results of Trendelenburg sign were negative. X-ray films showed that all patients got a bony union at osteotomy site of greater trochanter at 3-6 months after operation. And the interface between prosthesis and bone was stable. There was no prosthesis loosening or sinking during the follow-up. ConclusionClinging lesser trochanter osteotomy with Wagner cone could be an option to shorten the femur in THA for patients with Crowe type ⅠV DDH. It is effective in decreasing the risk of neurovascular injury.
The biggest advantages of network meta-analysis (NMA) are to compare the effectiveness of different interventions about one conditions using a quantitative way, pool the results of direct comparison and indirect comparison, and rank the effectiveness based on outcomes, so as to select the best decision for patients. In the paper we introduce the methods of applying GRADE system to NMAs based on the papers published by GRADE working group and other relative studies. The steps of using GRADE to NMAs are mainly based on four aspects: firstly, presenting direct and indirect effect estimates and 95% CI; secondly, rating of quality of direct and indirect estimates; thirdly, presenting the results of NMAs; and the last step is to rating the quality of NMA effect estimates. The methods of rating the quality of direct comparison are the same to use GRADE in traditional meta-analysis. The rating of the quality of the indirect estimates is based on the ratings of the two pairwise estimates that contributes to the indirect estimate of the comparison of interest. The lower confidence rating of the two direct comparisons constitutes the confidence rating of the indirect comparison. When both direct and indirect evidence are available, we suggest using the higher of the two quality ratings as the quality rating for NMA estimate. The four steps of rating the quality of NMA from GRADE working group have promoted the theoretical system of NMA. But the process requires the evaluators to be familiar with GRADE system, and conduct pilot test to make sure the evaluators had understood the items of GRADE system correctly. In addition, we also need to concern that the non-transitivity among different groups and the inconsistency between direct comparison and indirect comparison.