The Psychological Inflexibility in Pain Scale (PIPS) assesses both avoidance of pain and cognitive fusion with pain.
References:
Wicksell, R. K., Renöfält, J., Olsson, G. L., Bond, F.W. & Melin, L. (2008). Avoidance and cognitive fusion - central components in pain related disability? Development and preliminary validation of the Psychological Inflexibility in Pain Scale (PIPS). European Journal of Pain, 12, 491-500.
Vasiliou, V. S., Michaelides, M. P., Kasinopoulos, O., & Karekla, M. (2019). Psychological Inflexibility in Pain Scale: Greek adaptation, psychometric properties, and invariance testing across three pain samples. Psychological Assessment, 31(7), 895–904. https://doi.org/10.1037/pas0000705