A bias adjusted evidence synthesis of RCT and observational data: the case of total hip replacement

Petra Schnell-Inderst, Cynthia Paola Iglesias Urrutia, M Arvandi, O Ciani, R Matteucci Gothe, J Peters, Blom AW, RS Taylor, U Siebert

Research output: Contribution to journalArticlepeer-review


Evaluation of clinical effectiveness of medical devices differs in some aspects from the evaluation of pharmaceuticals. One of the main challenges identified is lack of robust evidence and a will to make use of experimental and observational studies (OSs) in quantitative evidence synthesis accounting for internal and external biases. Using a case study of total hip replacement to compare the risk of revision of cemented and uncemented implant fixation modalities, we pooled treatment effect estimates from OS and RCTs, and simplified existing methods for bias-adjusted evidence synthesis to enhance practical application. We performed an elicitation exercise using methodological and clinical experts to determine the strength of beliefs about the magnitude of internal and external bias affecting estimates of treatment effect. We incorporated the bias-adjusted treatment effects into a generalized evidence synthesis, calculating both frequentist and Bayesian statistical models. We estimated relative risks as summary effect estimates with 95% confidence/credibility intervals to capture uncertainty. When we compared alternative approaches to synthesizing evidence, we found that the pooled effect size strongly depended on the inclusion of observational data as well as on the use bias-adjusted estimates. We demonstrated the feasibility of using observational studies in meta-analyses to complement RCTs and incorporate evidence from a wider spectrum of clinically relevant studies and healthcare settings. To ensure internal validity, OS data require sufficient correction for confounding and selection bias, either through study design and primary analysis, or by applying post-hoc bias adjustments to the results.

Original languageEnglish
Pages (from-to)46-69
Number of pages24
JournalHealth Economics
Issue numberS1
Publication statusPublished - 31 Jan 2017

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  • bias adjustment
  • expert elicitation
  • generalized evidence synthesis
  • health technology assessment
  • medical devices

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