Using risk model judgements to better understand perceptions of synergistic risks

Putting knowledge into practice: Does information on adverse drug interactions influence people's dosing behaviour?

OBJECTIVE

Adverse drug events relating to drug-drug interactions are a common cause of patient harm. Central to avoiding this harm is the patients' understanding that certain drug combinations present a synergistic risk. Two studies tested whether providing individuals with information about a drug combination that presents a synergistic (cf. additive) risk would elicit higher perceived risk and, therefore, would result in greater precaution in terms of dosing behaviour.

DESIGN

Both studies employed an experimental design.

METHODS

Participants were presented with a scenario describing how two symptoms of an infection could each be treated by a different drug. In Experiment 1, information about the effects of combining the two drugs was varied: (1) no information, (2) combination elicits an additive risk, or (3) combination elicits a synergistic risk. In Experiment 2, the size of the risk (small or large) and the participant's role (patient or doctor) was also varied.

RESULTS

In both experiments, perceived risk and negative affect increased in response to information about the increased probability of side effects from the drug-drug interaction. Despite these increases, participants did not adjust their drug dosing behaviour in either experiment: Dosing was similar when these interactions were large or small, or when they were due to synergistic or additive effects.

CONCLUSIONS

People may struggle to transfer their knowledge of drug-drug interaction risks into decision-making behaviours. Care should be taken not to assume that holding accurate risk perceptions of a drug's side effect will result in decisions that help avoid adverse drug events. Statement of contribution What is already known on this subject? Adverse effects of drug-drug interactions are a cause of hospital admissions and increase morbidity and mortality. Patients' understanding that certain drug combinations present a synergistic risk is crucial to avoid harm. It is not clear whether synergistic drug interactions increase risk perception and influence dosing decisions. What does this study add? Perceived risk and negative affect increased in response to synergistic risk information. Despite these increases, participants did not adjust their drug dosing behaviour. People struggle to transfer their knowledge of drug-related risks into behavioural decisions.

Towards an understanding of adult judgments of synergistic health benefits

OBJECTIVE

Numerous scientific studies show that certain combinations of dietary and/or lifestyle factors produce health benefits which are greater than the sum of the benefits associated with each factor alone. To address an existing knowledge gap, we assessed the extent to which individuals understand that certain combinations present these 'synergistic health benefits'.

DESIGN

Health benefit judgments were obtained from lay adults for a range of dietary and/or lifestyle combinations that have been found to present synergistic benefits. Association between these judgments and socio-cognitive characteristics such as numeracy, education, and health interest (HI) were examined.

METHODS

Three hundred and fifty-two Swiss adults were presented with a description of one of eight synergistically beneficial combinations. Each participant provided a categorical benefit judgment (i.e., subadditive, additive, or synergistic) for the combination and explained the cognitive reasoning underlying their judgment. Participants completed measures of numeracy and HI.

RESULTS

The proportion of combinations judged to present a synergistic benefit was modest for 'macro-level' combinations (e.g., diet and exercise), but low for 'micro-level' combinations (e.g., two phytochemicals). Cognitive reasoning data showed that a higher proportion of judgments for micro-level (cf. macro-level) combinations were based on greater subjective epistemic uncertainty. Higher interest in health was associated with a better understanding of synergistic benefits, but numeracy and education level were not.

CONCLUSIONS

There is considerable scope to improve the extent to which lay adults understand that specific combination of diet and lifestyle behaviours can synergistically benefit their health. Our results enable us to make informed recommendations for public health interventions.

STATEMENT OF CONTRIBUTION

What is already known on this subject? Combining certain dietary and/or lifestyle factors can result in synergistic health benefits. People could maintain/enhance their health by combining these synergistic combinations. No previous studies have assessed the extent to which people understand that certain factors produce synergistic health benefits. What does this study add? This is the first study to identify that lay awareness of synergistic health benefits could be substantially improved. Neither education level nor numeracy moderate judgments of synergistic benefits, but health interest does. Individuals better understand that broad lifestyle behaviours (cf. specific foods and phytochemicals) are synergistic.