In an online survey of 443 practising UK GPs, researchers from the University of Oxford found 'wide-ranging inaccuracies' in participants’ estimates of the benefits and harms of treatments for long-term conditions, 'with overestimation of both benefits and harms predominating'.
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The inaccuracies are 'likely to meaningfully affect clinical decision-making and impede conversations with patients regarding treatment choices,' say the researchers.
Participants were asked to estimate the percentage absolute risk reduction or increase provided by 13 interventions for 10 long-term conditions on 17 key outcomes.
Each question described a fictional patient with a long-term condition for whom current guidelines recommend a treatment. Participants were asked to estimate the absolute risk reduction (or increase) in various outcomes conferred by the treatment over a defined time period.
The survey was distributed via CCGs, health boards, the NASGP and other groups to reach an undifferentiated pool of GPs.
The findings showed that most respondents had 'poor (and in some cases very poor)' knowledge of the absolute benefits and harms of treatments.
Overall, the researchers found an average of 10.9% of responses were correct allowing for ±1% margin in absolute risk estimates and 23.3% allowing a ±3% margin. The vast majority (87.7%) of responses overestimated and 8.9% of responses underestimated treatment effects.
Most respondents (64.8%) said they had ‘low’ or ‘very low’ confidence in their answers.
The reported inaccuracies in understanding could have negative implications for shared decision-making, say the authors. They give an example of a patient at low cardiovascular risk considering whether to take drug treatment for stage 1 hypertension: the discussion will be very different if the doctor understands the absolute risk reduction in cardiovascular events over 10 years to be 1% rather than 20%.
The authors admit they would not expect any GP to remember a large number of precise figures, but they express concern over the level of misestimation of treatment effects. They attribute the cause to a system issue rather than a lack of individual learning: quantitative information about the benefits and harms of treatments is difficult and time-consuming to find, they say.
Solutions suggested by the authors include improved guidelines and information resources to provide accessible and understandable quantitative information on both the benefits and harms of treatments. They emphasise that such information will need to be accompanied by research and measures to address the understanding and communication of risk in the consulting room, in addition to changes in the structural and cultural drivers that influence clinical practice.