title: Multilevel models for estimating incremental net benefits in multinational studies.
abstract: Multilevel models (MLMs) have been recommended for estimating incremental net benefits (INBs) in multicentre cost-effectiveness analysis (CEA). However, these models have assumed that the INBs are exchangeable and that there is a common variance across all centres. This paper examines the plausibility of these assumptions by comparing various MLMs for estimating the mean INB in a multinational CEA. The results showed that the MLMs that assumed the INBs were exchangeable and had a common variance led to incorrect inferences. The MLMs that included covariates to allow for systematic differences across the centres, and estimated different variances in each centre, made more plausible assumptions, fitted the data better and led to more appropriate inferences. We conclude that the validity of assumptions underlying MLMs used in CEA need to be critically evaluated before reliable conclusions can be drawn.
authors.affiliation: Department of Public Health and Policy, London School of Hygiene and Tropical Medicine, London, UK. richard.grieve@lshtm.ac.uk
authors.forename: Richard
authors.initials: R
authors.lastname: Grieve
authors.forename: Richard
authors.initials: R
authors.lastname: Nixon
authors.forename: Simon G
authors.initials: SG
authors.lastname: Thompson
authors.forename: John
authors.initials: J
authors.lastname: Cairns
mesh_terms: D003362:Cost-Benefit Analysis; D005060:Europe; D015276:Health Care Rationing; D006801:Humans; D038622:Internationality; D017059:Models, Econometric; D015233:Models, Statistical; D015337:Multicenter Studies as Topic