# The influence of professionals’ personal views and values in the development of guidelines for rare diseases: an example from phenylketonuria

## TL;DR

This paper explores how personal views of experts influence guidelines for phenylketonuria, highlighting the need for transparency in decision-making.

## Contribution

The study reveals how personal biases affect guideline development for rare diseases, emphasizing the need for transparent expert opinions.

## Key findings

- Most experts agree on maintaining metabolic control in adulthood but acknowledge dietary treatment's social impact.
- 68% of panelists preferred the risk of over-treatment rather than under-treatment.
- Experts emphasized cognitive and wellbeing measures as critical for treatment success.

## Abstract

In the process of guideline development, expert opinion is introduced when there is low-quality or no scientific evidence available. During the first revision of the European phenylketonuria guidelines, the limited data regarding adult treatment targets was interpreted and weighted in different ways by different professionals. In this study, we have recorded and analyzed personal experience and views that may affect decisions.

A web-based questionnaire was sent to all panelists involved in the revision of the guidelines (n = 23), evaluating demographics, opinion about treatment targets, interpretation of scientific data and general views to establish adult specific treatment guidelines.

19 panelists responded. Most acknowledged the importance of maintaining metabolic control even in adulthood with target levels in line with previous recommendations, but that dietary treatment is a limiting factor for social life. 68% preferred the risk of over-treatment rather than undertreatment. The great majority considered cognitive, behavioral and wellbeing measures to be critical to measure treatment success. 58% considered significant group differences of 1 SD or less in neuropsychological tasks to be clinically significant.

Results highlight differences in expert opinions and the importance of making them more transparent to reach less-biased recommendations.