Mediation analysis of the relationship between institutional research activity and patient survival

BMC Medical Research Methodology

Theis Lange²  Andreas du Bois¹  Justine Rochon³ 

[1] Department of Gynecology and Gynecologic Oncology, Kliniken Essen-Mitte, Essen, Germany;Department of Biostatistics, University of Copenhagen, Copenhagen, Denmark;Institute of Medical Biometry and Informatics, University of Heidelberg, Im Neuenheimer Feld 305, Heidelberg 69120, Germany

关键词: Survival analysis;    Mediation;    Healthcare outcomes;    Research activity;    Trial effect;   

Others  :  866490
DOI  :  10.1186/1471-2288-14-9

 received in 2013-08-01, accepted in 2014-01-14,  发布年份 2014

【 摘 要 】

Background

Recent studies have suggested that patients treated in research-active institutions have better outcomes than patients treated in research-inactive institutions. However, little attention has been paid to explaining such effects, probably because techniques for mediation analysis existing so far have not been applicable to survival data.

Methods

We investigated the underlying mechanisms using a recently developed method for mediation analysis of survival data. Our analysis of the effect of research activity on patient survival was based on 352 patients who had been diagnosed with advanced ovarian cancer at 149 hospitals in 2001. All hospitals took part in a quality assurance program of the German Cancer Society. Patient outcomes were compared between hospitals participating in clinical trials and non-trial hospitals. Surgical outcome and chemotherapy selection were explored as potential mediators of the effect of hospital research activity on patient survival.

Results

The 219 patients treated in hospitals participating in clinical trials had more complete surgical debulking, were more likely to receive the recommended platinum-taxane combination, and had better survival than the 133 patients treated in non-trial hospitals. Taking into account baseline confounders, the overall adjusted hazard ratio of death was 0.58 (95% confidence interval: 0.42 to 0.79). This effect was decomposed into a direct effect of research activity of 0.67 and two indirect effects of 0.93 each mediated through either optimal surgery or chemotherapy. Taken together, about 26% of the beneficial effect of research activity was mediated through the proposed pathways.

Conclusions

Mediation analysis allows proceeding from the question “Does it work?” to the question “How does it work?” In particular, we have shown that the research activity of a hospital contributes to superior patient survival through better use of surgery and chemotherapy. This methodology may be applied to analyze direct and indirect natural effects for almost any combination of variable types.

【 授权许可】

   
2014 Rochon et al.; licensee BioMed Central Ltd.

【 图 表 】

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