In our opinion, the most powerful arguments against the inclusion of PRI in the Guides are that (1) PRI assessments are likely to be unreliable and (2) they might lead to systematic errors in assessment, such that persuasive patients can “game the system” and get inappropriately high impairment awards. Both of these arguments derive from the permise that it is very difficult for examiners to determine the extent to which patients are affected by their pain. These difficulties were succinctly captured by Scarry when she said: “To have great pain is to have certainty; to hear that another person has pain is to have doubt.” The problem of reliability and validity of PRI assessment is much more than an academic problem in measurement theory. The Guides serves the societal role of providing the equitable method of compensation individuals who ability to function has been compromised by a medical condition. For the Guides must employ assessment procedures that are reliable and valid, rather than capricious ones that can be manipulated by persuasive patients. Thus, regardless of how severely pain affects individuals with various medical conditions, a PRI assessment system must have reasonable reliability and validity to accomplish the societal goal of fairly compensating them.
In fact, the key issue separating proponents and opponents of impairment due to pain is the weight they place on ease of measurement of PRI vs. relevance of PRI. Advocates for PRI emphasize that pain has great relevance to the ability to function of individuals who have various medical conditions, but these advocates tend to downplay the problems of measuring PRI. Opponents tend to emphasize problems in measurement but ignore the issue of relevance. In principle, empirical research could be performed to determine the strength of the independent contribution that pain makes to the burden of illness borne by individuals with various medical condition, and whether examiners can reliably and validly assess PRI. Considerable research has been done on the first issue, at least for some common painful conditions such as disorders of the lumbar spine. Unfortunately, though, essentially no research has been done on the issue of determining the reliability and validity of PRI assessments. Construct validation research is greatly needed in this area. At this time, as a practical matter, decisions regarding PRI for purposes of the Guides’ Sixth Edition must be based on judgment rather than empirical data.