CRD summary: The authors concluded that, compared with cyclophosphamide, mycophenolate mofetil produced more responses to treatment and lower rates of most adverse events in the treatment of lupus nephritis. These conclusions are in line with the evidence presented, but should be treated with some caution in view of the short duration of most included studies and the poor reporting of review methods.

CRD commentary: This review addressed a clear research question. The inclusion criteria for the participants and interventions were clear, whereas broad criteria were used for study designs and outcomes. The authors searched two databases without language restrictions and made some attempt to locate unpublished studies. Publication bias was not assessed, so it is difficult to comment on the risk of this bias in the review. The validity of RCTs included in the efficacy analysis was assessed using a standard method. The methods used for the study selection and validity assessment were not reported, making it difficult to assess the risk of errors and bias during these stages of the review. Two independent reviewers extracted the data. Details of the included studies were presented in the paper; additional files are available on the Arthritis and Research Therapy website (accessed 03/10/2007). See Web Address at end of abstract. RCTs were combined by meta-analysis to give pooled estimates of efficacy and safety of MMF relative to CCP. Although the authors stated that they assessed heterogeneity, lack of detailed reporting makes it difficult to comment on whether the trials were sufficiently homogeneous for pooling to be appropriate. The appropriateness of combining the cohort studies is unclear given the diversity of the study designs and outcomes included. As the authors noted, most studies involved relatively short periods of treatment and follow-up and the results may not be applicable to longer term treatment. Overall, the authors' conclusions are in line with the evidence presented, but should be treated with some caution in view of the limitations of the evidence and lack of reporting of review methods. The review was partly funded by a company working on behalf of the company developing MMF as a treatment for lupus nephritis.