Does Shared Decision Making in Cancer Treatment Improve Quality of Life? A Systematic Literature Review.

BACKGROUND: The growing consensus espousing the use of shared decision making (SDM) in cancer treatment has coincided with the rise of health care evaluation paradigms that emphasize quality of life (QOL) as a central outcome measure. This review systematically examines the association between treatment SDM and QOL outcomes in cancer. METHODS: A range of bibliographic databases and gray literature sources was searched. The search retrieved 16,726 records, which were screened by title, abstract, and full text to identify relevant studies. The review included 17 studies with a range of study designs and populations. Data were extracted on study methods, participants, setting, study or intervention description, outcomes, main findings, secondary findings, and limitations. Quality appraisal was used, in conjunction with a narrative approach, to synthesize the evidence. RESULTS: The review found weak, but suggestive, evidence for a positive association between perceived patient involvement in decision making, a central dimension of SDM, and QOL outcomes in cancer. The review did not find evidence for an inverse association between SDM and QOL. The poor methodological quality and heterogeneity of the extant literature constrained the derived conclusions. In addition, the literature commonly treated various subscales of QOL instruments as separate outcomes, increasing the probability of spurious findings. CONCLUSIONS: There is weak evidence that aspects of shared decision-making approaches are positively associated with QOL outcomes and very little evidence of a negative association. The extant literature largely assessed patient involvement, only capturing one aspect of the shared decision-making construct, and is of poor quality, necessitating robust studies examining the association.