How to critically appraise and apply meta-analyses in clinical practice.

AIM: Prompted by a clinical question, we critically appraised a meta-analysis of efficacy and safety of mycophenolate mofetil (MMF) versus cyclophosphamide (CYC) in the treatment of proliferative lupus nephritis.
METHODS: Systemic reviews and a meta-analysis are introduced to the reader in the perspective of a clinical scenario that raises questions about applicability of certain treatment options in clinical practice. Critical appraisal of meta-analysis addresses three questions. (i) What are the results? (ii) Are the results valid? (iii) How can I apply the results to my patient care?
RESULTS: A meta-analysis paper titled 'Mycophenolate mofetil is as efficacious as, but safer than, cyclophosphamide in the treatment of proliferative lupus nephritis: a meta-analysis and meta-regression'by Mak et al. (2009) was selected. Our critical appraisal identified several strengths of the paper, such as having a clearly focused clinical question, considering clinically important outcomes, using appropriate inclusion criteria to select primary studies, assessing quality of selected papers, good reproducibility in the assessment of primary studies and performing sensitivity analysis and meta-regression to account for heterogeneity. Nevertheless, we also identified several weaknesses, such as possibly missing out other relevant studies, possible selection bias, low quality of some primary studies used and lack of data on cost effectiveness.
CONCLUSION: Meta-analyses have an important role in the implementation of evidence-based practice and shaping of future research. Despite the undoubted advantages, meta-analyses are no panacea. Caution, therefore, has to be applied when using the results of meta-analyses in clinical practice, due to methodological limitations of the meta-analyses and limitations in the primary studies used.