Five of the 8 interventions aimed at improving informed choice about screening tests above usual care did so. The heterogeneity of the interventions and screening disease target preclude drawing firm conclusions about how this was accomplished. Those that did enhance informed choice involved screening for breast cancer, colorectal cancer, Type 2 diabetes, and prostate cancer. Three different decision aids, an “evidence bases” booklet, and an informed choice-based invitation constituted the enhanced interventions. All 3 decision aids resulted in more informed choices as measured by the MMIC. It is unclear whether these interventions enhanced informed choice because of better understanding of relevant information alone as effects on attitudes toward screening were inconsistent. Although decision aids have been shown repeatedly to increase relevant knowledge, it remains unclear from the published literature whether and how decision aids affect values clarification as related to attitudes toward the behavioral decision.34
With the limited evidence kept in mind, the pattern of findings suggests that the most promising prescreening interventions may be decision aids, regardless of limited understanding of how they achieve more informed choice.
In 7 of the 8 studies, the screening interventions increased knowledge about the screening test and condition above usual or no education. The measures of knowledge were investigator developed for each study, except in each of 2 cases in which the investigators conducted a subsequent study using the same measure.5,6,28,33
The investigators often used the content of government leaflets to inform the development of the interventions. Two solicited input from members of the target population. There was no consistency among the studies for the type or extent of the information included. Further, the criteria by which the investigators determined that sufficient knowledge had been acquired varied. Regardless of the notable finding that 7 of the 8 studies increased knowledge, it remains unknown whether the information learned was the most relevant or sufficient to making a screening test decision.
Attitudes were assessed in 6 studies, and results were inconsistent: they became more negative with use of the enhanced interventions in 3, more positive in one, and unchanged in 2. Intentions were assessed in 7 of the 8 studies: they were unchanged in 5 and decreased in 2. Screening up-take was assessed in 4 studies: it was unchanged in 2, increased in one, and decreased in another. The limited evidence did not suggest that increasing informed choice affects screening uptake.
The aim of the current review was to extend and update the Jepson review of 6 randomized controlled trials of health screening decisions in which knowledge, uptake, and informed decision making were assessed. Jepson and colleagues concluded that there was some evidence that changing the format of informed-choice interventions (videos, leaflets with decision trees, or computer programs) from well-prepared leaflets does not increase knowledge, satisfaction, or test uptake. They also concluded that it remained unclear whether enhancing informed choice affects screening uptake. With the addition of these 8 studies, there is now limited evidence to suggest that moving beyond well-prepared leaflets to decision aids may lead to interventions that more consistently enhance knowledge and result in more informed choice. Further, there is some additional evidence to suggest that enhancing informed choice does not affect screening uptake.
In the studies summarized by Jepson and colleagues, informed choice was a less well-defined construct that had been used to inform the design of leaflet interventions aimed at increasing screening behavior. The construct was inconsistently defined and interpreted in the design of the interventions. Study outcomes were limited to components of, and proxies for, the more contemporary definition of informed choice. Although significant variation remained among the studies in the current review, informed choice was described using the definition proposed by Marteau and colleagues7
in 4 of the studies; and in 3 studies, the MMIC was used to measure informed choice. Six used subscales of the decisional conflict scale to measure constructs that might be considered a consequence of informed choice. Yet despite a decade of more consistent thinking about the elements of informed choice along with publication of a validated measure, progress has been slow in answering important research questions about how interventions can be designed to effectively increase informed choice and in doing so whether they change screening behavior.
The diversity in content, format, and platform makes it challenging to compare outcomes across the studies. Even within each study, it is unknown how the interventions increased knowledge, or in some cases, informed choice. Several mailed the intervention to homes of the target population and failed to assess whether participants read or used the intervention, jeopardizing the fidelity of the intervention. Although the quality of the studies varied as well, in some cases it was poor.
Overall, the continuation of inconsistency in definitions of informed choice and sufficient relevant knowledge, the use of different types of interventions, and the diversity in outcome measures suggest that data from this review add little to our understanding of the effectiveness of screening interventions in enhancing informed choice. The impact of the increasing informed choice appears to date not to have an effect on screening behavior, but this is supported by limited data.
The strength of this review lies in updating the findings by Jepson published a decade earlier, providing new evidence that informed-choice interventions can increase acquisition of relevant knowledge and enhance informed choice above usual care but not affect screening uptake.
There are 2 key limitations of this review. One is a potential failure to identify all relevant research for inclusions. Efforts were undertaken to avoid this pitfall by reviewing the reference lists of all identified studies. The second is the potential for publication bias. All studies included were published in journals, and the grey literature was not reviewed.
Despite progress in defining and measuring informed choice, the findings of this review fall short of furthering our understanding about the effective components of interventions designed to facilitate making informed choices about screening. Although a large literature was identified over the past decade on health screening interventions aimed at increasing knowledge, only 8 studies met the criteria for inclusion, a randomized control design of an intervention aimed at enhancing informed choice. Only a subset of 4 used a validated measure of the primary outcome, informed choice.26-28,33
These 4 studies included interventions to enhance screening for breast cancer, Type 2 diabetes, and colorectal cancer, the diversity making it inadvisable to draw conclusions on the role of health screening interventions in enhancing informed choice.
The quantity and quality of evidence will hopefully expand over the coming decade, given the availability of a formal definition for informed choice and publication of a validated measure. However, the small number of studies identified in this review and the remaining inconsistencies in design and measures suggest cautious optimism is warranted.