Pain dominates measurements of elbow function and health status

Abstract

Background: Elbow function can be quantified with use of physician-based elbow-rating systems and health status questionnaires. Our hypothesis was that pain has a strong influence on these scores, which overwhelms the influence of objective factors such as motion.

Methods: One hundred and four patients were evaluated, at a minimum of six months (average, forty-six months) after the latest surgery for an intra-articular fracture of the elbow, with use of three physician-based evaluation instruments (Mayo Elbow Performance Index [MEPI], Broberg and Morrey rating system, and American Shoulder and Elbow Surgeons Elbow Evaluation Instrument [ASES]), an upper-extremity-specific health status questionnaire (Disabilities of the Arm, Shoulder and Hand [DASH]), and a general health status questionnaire (Short Form-36 [SF-36]). Multivariate analysis of variance and regression modeling were used to identify the factors that account for the variability in scores derived with these measures-in other words, which factors have the strongest influence on the final score.

Results: Pain alone accounted for 66% of the variability in the MEPI scores, 59% of the variability in the Broberg and Morrey scores, and 57% of the variability in the ASES scores. Models that included other factors accounted for only slightly more variability (73%, 79%, and 79%, respectively), and those that did not include pain accounted for only 22%, 41%, and 41% of the variability. Thirty-six percent of the variability in the DASH scores could be accounted for by pain alone, and 45% could be accounted for by pain and range of motion. Models not including pain accounted for only 17% of the variability in the DASH scores.

Conclusions: Pain has a very strong influence on both physician-rated and patient-rated quantitative measures of elbow function. Consequently, these measures may be strongly influenced by the psychosocial aspects of illness that have a strong relationship with pain, and objective measures of elbow function such as mobility may be undervalued. It may be advisable to evaluate pain separately from objective measures of elbow function in physician-based elbow ratings.