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.