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.
Wicksell, R.K., Lekander, M., Sorjonen, K. and Olsson, G.L. (2010), The Psychological Inflexibility in Pain Scale (PIPS) – Statistical properties and model fit of an instrument to assess change processes in pain related disability. European Journal of Pain, 14, 771, e1-771.e14. DOI: 10.1016/j.ejpain.2009.11.015