QScale: A Visual Scale for Standardized Pain Sensitivity Measurements - An Explorative Study in Pain-free Subjects

An increased pain sensitivity plays a key role in the development and
persistence of chronic pain. This pain sensitivity can be measured by
performing electric Quantitative Sensory Testing (eQST); a technique widely
used in clinical research, but not yet in clinical practice. The lack of
structural application of pain sensitivity measurements clinical practice can
be explained by, among other things, the variability in the measurement. This
is mainly caused by (1) differences in the way researchers perform the pain
sensitivity measurement and (2) differences in the way subjects interpret and
perform the measurement related tasks. An eQST measurement can be conducted in
various ways since it is not standardized when it comes to the instructions and
equipment. Besides the fact that instructions can be given slightly different
each time, the measurement outcome is also dependent on the participants*
interpretation of the oral instruction. In a scientific study, this variability
can mainly be overcome by having one researcher conducting all measurements. In
clinical practice however, there will be many different people performing the
measurement, resulting in variability in the measurement that needs to be
overcome.

At BSS, the QScale has been developed specifically for electrical skin
stimulation on the basis of drawings of the perceived stimulation at different
stimulus strengths. This has resulted in a scale in which participants can
report both the quality as well as the intensity of the sensations by
appointing one of the visualizations instead of an oral description
(*annoying*, *painful*). This visual scale permits to link changes in sensation
to the strength of the stimulus, without omitting a strong dependency on the
oral instruction of the researcher or its interpretation by the subject. The
next step in the development of the QScale is to explore the validity (cold
pressor test) and reliability (one week test-retest) of the scale.
Additionally, comparisons will be made between the oral instructions and the
QScale (part A) and between two different electrodes while given visual
instructions (part B).

The primary objective is to explore the validity and reliability of the QScale
during pain sensitivity measurements in pain-free subjects.

Mono-center, cross-sectional study.

Participants will be asked to come to the Human Physiology Lab of the BSS group
at the University of Twente for two sessions, which will be scheduled one week
apart from one another. The general outline of the study procedure of part A
and part B is identical. Before the first pain sensitivity measurements are
conducted, the participants will first be connected to the equipment and
familiarized with the measurement. Shortly thereafter a cold pressor test is
carried out, in which the participant has to immerse one hand into the water
for a maximum of two minutes. As the cold pressor test is also a cardiovascular
test, there are risks involved for participants with (un)known cardiovascular
problems. The cold pressor test can be experienced as painful. Directly after
this test another pain sensitivity measurement will be done. The exact same
procedure will be repeated approximately one week after the first appointment.
Participants are compensated for their participation and will obtain no direct
personal benefit.