Page 217 - Let them speak Towards a patient reported outcome measure set for

General discussion
Behavior Checklist (ABCL). The set also showed mostly moderate to strong
correlations with these instruments, indicating that they measure similar
constructs. In particular, most PROMIS CATs and SFs were reliable, required
completion of only 4 – 13 items, and showed no floor and ceiling effects,
indicating that they measure the full spectrum of functioning in individuals
with GID. The stopping rule for PROMIS CATs is currently being optimized,
which will also result in fewer items administered, especially among
individuals who report no symptoms (32). The findings of our psychometric
study provide the first evidence supporting the usability of the core PROM
set in the GID population. Nonetheless, additional psychometric evaluation
and validation, particularly within specific subgroups, remains necessary.
The core PROM set is intended to be applicable across the entire GID
population, also including individuals with severe to profound ID. For this
group, proxies such as caregivers are expected to complete the PROMs
on their behalf. However, given the communication challenges within this
population, proxy reporting can be difficult. For instance, when a 10-year-
old girl with Rett syndrome cries or screams, it may be unclear whether she
is angry, anxious, or overstimulated, as she cannot express how she feels.
This makes it difficult for her caregiver to report on her emotional state.
Despite this challenge, research suggests that caregivers often possess
tacit knowledge, which is a deep, experience-based understanding of the
individual’s health and well-being (33, 34). They may, for example, be able to
describe a person’s pain experience and pain-related behaviors even when
direct communication with the person is not possible (35). This supports
the fact that caregivers may be suitable proxy reporters for individuals with
severe or profound ID. Nonetheless, further research is needed, including
assessments of whether caregivers feel able to report on all PROs included
in the core PRO(M) set. This aspect was not included in the psychometric
study described in this thesis, but is also part of the broader psychometric
project in which the core PROM set is being further evaluated across the
entire GID population. As part of this project, caregivers were asked, after
completing each PROM, whether they felt able to empathize with their child
in relation to that specific health aspect being measured (e.g., anxiety).
Nevertheless, when developing a full CO(M)s, it might be necessary to also
include ObsROMs. These ObsROMs may address the challenges in proxy
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