<qa>  What is the sensitivity of opioid blockade?Offset analgesia is thought to reflect a form of temporal pain inhibition which is usually defined by three stimulus temperature phases: a baseline phase followed by a manipulation phase in which the temperature is briefly increased and returns to the baseline temperature during an offset phase. A reduction in pain ratings is observed approximately 15s after the temperature drop third phase, which is 50 lower than ratings at the same time point for constant trials that continued 48C for 40s. No studies have examined offset analgesia in a chronic pain cohort or its sensitivity of opioid blockade. 