title: Assessing generalisability by location in trial-based cost-effectiveness analysis: the use of multilevel models.
abstract: Cost-effectiveness analysis (CEA) in health care is increasingly conducted alongside multicentre and multinational randomised controlled clinical trials (RCTs). The increased use of stochastic CEA is designed to account for between-patient sampling variability in cost-effectiveness data assuming that observations are independently distributed. However, between-location variability in cost-effectiveness may result if there is a hierarchical structure in the data; that is, if there is correlation in costs and outcomes between patients recruited in particular locations. This may be expected in multi-location trials given that centres and countries often differ in factors such as clinical practice, patient case-mix and the unit costs of delivering health care. A failure to acknowledge this feature may lead to misleading conclusions in a trial-based economic study. Multilevel modelling (MLM) is an analytical framework that can be used to handle hierarchical cost-effectiveness data. Using data from a recently conducted economic analysis, this paper shows how multilevel modelling can be used to obtain (a) more appropriate estimates of the population average incremental cost-effectiveness and associated standard errors compared to standard stochastic CEA; and (b) location-specific estimates of incremental cost-effectiveness which can be used to explore appropriately the variability between centres/countries of the cost-effectiveness results.
authors.affiliation: Centre for Health Economics, University of York, UK. am126@york.ac.uk
authors.forename: Andrea
authors.initials: A
authors.lastname: Manca
authors.forename: Nigel
authors.initials: N
authors.lastname: Rice
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Sculpher
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Briggs
mesh_terms: D003362:Cost-Benefit Analysis / Q000379:methods*; D005260:Female; D005843:Geography; D006801:Humans; D007044:Hysterectomy / Q000191:economics / Q000379:methods; D010535:Laparoscopy / Q000191:economics; D017059:Models, Econometric; D015337:Multicenter Studies as Topic / Q000191:economics* / Q000706:statistics & numerical data; D019982:Organizational Case Studies; D019057:Quality-Adjusted Life Years; D016032:Randomized Controlled Trials as Topic / Q000191:economics* / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D017062:Small-Area Analysis; D013269:Stochastic Processes; D016896:Treatment Outcome; D006113:United Kingdom