Psychological illness influences the experience and expression of pain and disability. We tested three null hypotheses: (1) patients with nonspecific pain (medically unexplained and idiopathic) and patients with specific pain (discrete and verifiable) are equally likely to screen for psychiatric illnesses based on a validated screening questionnaire; (2) the presence of psychiatric illness (from a screening questionnaire) will not predict whether patients have specific or nonspecific pain type; and (3) across all patients and regardless of whether they have specific or nonspecific pain, psychiatric illness will not predict disability as measured by the Disabilities of the Arm Shoulder and Hand (DASH) questionnaire. We rejected all null hypotheses. The 41 patients with nonspecific arm pain were more likely than the 40 patients with specific arm pain to screen for a somatoform disorder (34% versus 7.5%), posttraumatic stress disorder (24% versus 7.5%), and panic disorder (12.2% versus 5%). The presence of anxiety and somatoform disorders predicted pain type (nonspecific versus specific) and arm-specific disability (DASH). Somatoform disorder was the strongest predictor of pain type and DASH scores. Based on a screening questionnaire, a comorbid psychiatric illness, a somatoform disorder in particular, is associated with nonspecific arm pain and arm-specific disability.
Level of evidence: Level II, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.