PMU56 Health Economic Evaluation Alongside Stepped Wedge Trials: A Methodological Systematic Review and Recommendations of Appropriate Modelling Approaches

Abstract

Recently, there has been an increase in use of the stepped wedge trial (SWT) design in the context of health services research, due to its pragmatic and methodological advantages over the parallel group design. Our objectives were twofold: review the statistical methods used when conducting economic evaluations alongside SWTs and make a proposal for appropriate methods to use. A methodological systematic literature search was conducted (up to February 2020) in the PubMed, Scopus, Cochrane and NHS-EED databases to find and evaluate studies where there was an intention to conduct an economic evaluation alongside a SWT. A total of 69 studies were identified and included in this review. 54 studies were published protocols, 8 economic evaluations and 7 studies reporting full trial results. Included studies varied in terms of their reporting of statistical methods, in both detail and methodology. There were 34 studies that did not report any statistical methods for the economic evaluation and only 16 studies reported appropriate methods, mainly using some form of mixed/multilevel models, seemingly unrelated regression and Bayesian techniques with Monte Carlo simulation. The remaining studies failed to appropriate account for clustering, correlation or adjusted for time. The use of appropriate statistical methods that account for time, clustering, and correlation between costs and outcomes is an important part of SWT health economics analysis and in particular we recommend the use of one of the following methods: hierarchical/multilevel models, seemingly unrelated regressions, two-stage bootstrap methods and bivariate Bayesian models. We also propose the extension of the CHEERS checklist in order to encourage transparent reporting of economic evaluations alongside SWTs.