Quantitative analysis of sponsorship bias in economic studies of antidepressants.

BACKGROUND

Concern is widespread about potential sponsorship influence on research, especially in pharmacoeconomic studies. Quantitative analysis of possible bias in such studies is limited.

AIMS

To determine whether there is an association between sponsorship and quantitative outcomes in pharmacoeconomic studies of antidepressants.

METHOD

Using all identifiable articles with original comparative quantitative cost or cost-effectiveness outcomes for antidepressants, we performed contingency table analyses of study sponsorship and design v. study outcome.

RESULTS

Studies sponsored by selective serotonin reuptake inhibitor (SSRI) manufacturers favoured SSRIs over tricyclic antidepressants more than non-industry-sponsored studies. Studies sponsored by manufacturers of newer antidepressants favoured these drugs more than did non-industry-sponsored studies. Among industry-sponsored studies, modelling studies favoured the sponsor's drug more than did administrative studies. Industry-sponsored modelling studies were more favourable to industry than were non-industry-sponsored ones.

CONCLUSIONS

Pharmacoeconomic studies of antidepressants reveal clear associations of study sponsorship with quantitative outcome.