The purpose of this stu
dy was to
determine whether session-specific measures of negative pain-relate
d affect woul
d account for longitu
dinal variability in the ratings of the evoke
d thermal pain. Pain-free subjects rate
d pain evoke
d on the posterior leg using thermal stimuli of 45°, 47°, 49°, an
d 51°C on 3 occasions, each separate
d by 2 weeks. Session-specific negative pain-relate
d affect measures were also collecte
d. Ratings of pain
decrease
d significantly with repeate
d testing,
demonstrating a systematic change in rating from the first to secon
d sessions that range
d from a mean of 5.3 at 47°C to 9.1 at 49°C. In a
ddition, large ran
dom variation occurre
d across all sessions, resulting in minimal
detectable change ranging from 14 to 27. The least variability occurre
d when a mean rating of the 4 temperatures was use
d. Session-specific measures of pain-relate
d affect
decrease
d with repeate
d testing; however, the significant between-subject variability in both rating of pain an
d pain-relate
d affect were not relate
d to each other. No associations were i
dentifie
d between psychological measures an
d variability in rating of evoke
d pain. Future stu
dies of the variability in ratings shoul
d consi
der other factors such as attentional focus.
Perspective
The individual variability in thermal rating was not explained by individual variation in session-specific measures of negative pain-related affect. The results of this study support the use of repeated baseline measures of thermal stimuli when feasible. When this is not possible, the variability in ratings of thermal stimuli over multiple sessions is reduced when the mean of multiple temperatures is used.