Cost-effectiveness research in cancer therapy: a systematic review of literature trends, methods and the influence of funding.

OBJECTIVE: To perform a first-time analysis of the cost-effectiveness (CE) literature on chemotherapies, of all types, in cancer, in terms of trends and change over time, including the influence of industry funding.

DESIGN: Systematic review.

SETTING: A wide range of cancer-related research settings within healthcare, including health systems, hospitals and medical centres.

PARTICIPANTS: All literature comparative CE research of drug-based cancer therapies in the period 1986 to 2015.

PRIMARY AND SECONDARY OUTCOME MEASURES: Primary outcomes are the literature trends in relation to journal subject category, authorship, research design, data sources, funds and consultation involvement. An additional outcome measure is the association between industry funding and study outcomes.

ANALYSIS: Descriptive statistics and the χ2 , Fisher exact or Somer's D tests were used to perform non-parametric statistics, with a p value of <0.05 as the statistical significance measure.

RESULTS: Total 574 publications were analysed. The drug-related CE literature expands over time, with increased publishing in the healthcare sciences and services journal subject category (p<0.001). The retrospective data collection in studies increased over time (p<0.001). The usage of prospective data, however, has been decreasing (p<0.001) in relation to randomised clinical trials (RCTs), but is unchanging for non-RCT studies. The industry-sponsored CE studies have especially been increasing (p<0.001), in contrast to those sponsored by other sources. While paid consultation involvement grew throughout the years, the declaration of funding for this is relatively limited. Importantly, there is evidence that industry funding is associated with favourable result to the sponsor (p<0.001).

CONCLUSIONS: This analysis demonstrates clear trends in how the CE cancer research is presented to the practicing community, including in relation to journals, study designs, authorship and consultation, together with increased financial sponsorship by pharmaceutical industries, which may be more influencing study outcomes than other funding sources.