IDIOPATHIC ARM PAIN

Background: Arm pain with little or no objective abnormality (referred to herein as idiopathic arm pain) is a common and frustrating problem for both patients and physicians. We investigated the relative effect of idiopathic arm pain and arm pain due to a discrete diagnosis on upper-extremity-specific health status. Methods: The Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire was completed by 3888 patients seen over a twelve-month period. Scores for the entire sample, for 496 patients diagnosed with idiopathic arm pain, and for 1379 patients diagnosed with one of twenty-one discrete conditions were compared. Results: Patients with idiopathic pain reported substantial and highly variable upper-limb-specific dysfunction (average DASH score [and standard deviation], 36 ± 24 points). Patients with discrete diagnoses also exhibited substantial variation (average standard deviation, 25; range, 6 to 27) as well as long right tails indicating floor effects, particularly for less severe conditions (Pearson correlation of r = –0.87 between the mean DASH score and skewness). Analysis of variance confirmed the ability of the DASH instrument to discriminate among groups of diagnoses of varying severity, but post hoc Tukey analysis identified ten subgroups with substantial overlap of the DASH scores. Conclusions: Patients with idiopathic arm pain report substantial and highly variable upper-extremity dysfunction. The wide variations observed in the DASH scores of the patients with idiopathic pain and those with discrete diagnoses are greater than would be expected on the basis of the variations in the objective pathological conditions and may reflect the strong influence of psychological and sociological factors on health status measures.