Page 44 - Let them speak Towards a patient reported outcome measure set for

Chapter 2
outcome set. It serves as a starting point for discussion about a more
universal approach to the selection of relevant outcomes and instruments,
creating a bridge between GNDs and ID fields to enable evidence-based
general ID care and measuring effectiveness of innovative therapies.
Reported outcomes
From a total of 312 studies, there were 438 different reported outcomes
clustered into 91 different outcomes. We encountered differences
in terminology for similar constructs, such as ‘aberrant behaviors’,
‘challenging behaviors’, ‘behavioral problems’, and ‘severe behavioral
manifestations’. This may conflict with generalizability and clarity among
clinical trials, demonstrating the need for semantic harmonization.
Similarly, overlap in PROs across the International Consortium for Health
Outcomes Measurement standard sets was recently examined, identifying
307 different PROs referring to 22 unique PRO concepts.37 Furthermore,
(HR-)QoL was reported in 74 clinical trials, using 23 different instruments.
Although HR-QoL is an important outcome, this broad, abstract, and
multidimensional concept can cover different concepts, obscuring the
construct to be measured. According to the FDA, an HR-QoL measure
should at a minimum capture physical, psychological (including emotional
and cognitive), and social functioning.18
Outcome measurement instruments
We identified 457 different outcome measurement instruments to measure
PROs (n = 213), ClinROs (n = 54), ObsROs (n = 48), and PerfOs (n = 157), with
288 instruments (63%) only used in one clinical trial in the past decade. The
large number of different instruments used in clinical trials is not surprising,
considering the heterogeneity in levels of intellectual functioning, patients
and researcher preferences, availability of instruments that are appropriate
to specific conditions, and regional preferences. Furthermore, for novel drugs
with yet unknown efficacy, multiple domains might be studied requiring
different instruments, to investigate effectiveness and identify potential
subgroups who benefit most from the intervention. This is also reflected
by the large amount of ad-hoc designed symptom- specific and condition-
specific instruments, hampering extrapolation and interpretation of the
results. Yet, it is laborious to examine validity, reliability, and responsiveness
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