PSYCHOLOGICAL QUESTIONNAIRES - DO ABNORMAL SCORES PRECEDE OR FOLLOW FIRST-TIME LOW-BACK-PAIN

Study Design. A prospective study of psychological risk factors for fi rst-time low back pain with repeated use of psychological questionnair es. Objectives. To measure the reproducibility of scores from psycholo gical questionnaires, and to compare this with changes that follow an individual's first attack of back pain. Secondly, to determine which s cores predict first-time back pain. Summary of Background Data. ''Abno rmal'' psychometric scores are associated with several aspects of back pain behavior. Little is known, however, about their reproducibility or long-term stability, and there has been no definitive answer to the question: which comes first, ''abnormal'' scores or low back pain? Me thods. 403 volunteers with no history of ''serious'' low back pain (de fined as pain requiring medical attention or absence from work) partic ipated in a functional spinal assessment. At the time of initial asses sment and at 6-month intervals thereafter, the volunteers completed th e following questionnaires: the Health Locus of Control, which was sub divided into three sections labelled ''Internal,'' ''Powerful others,' ' and ''Chance''; the Modified Somatic Perception Questionnaire; and t he Zung depression scale. Scores from the Modified Somatic Perception Questionnaire; and the Zung depression scale. Scores from the Modified Somatic Perception Questionnaire and from the Zung depression scale w ere added to form a measure of psychological distress. Additional ques tionnaires inquired about any back pain experienced in the previous 6 months. Only three volunteers had left the study at the 18-month follo w-up. At that time 162 participants had reported ''any'' low back pain , of which 79 were ''serious.'' Results. Intraclass correlation coeffi cients for scores repeated after 6 months ranged from 0.67-0.80, and r eproducibility of scores was equally high between the 0-, 6-, 12- and 18-month assessments. None of the scores were affected by ''any'' low back pain, and only the Modified Somatic Perception Questionnaire scor es changed after ''serious'' back pain was reported. In a multivariate analysis, the most significant predictor of first time ''serious'' or ''any'' back pain was a history of non-''serious'' or ''any'' back pa in was a history of non-''serious'' back pain (P < 0.001). Of the psyc hological factors, the sum of Modified Somatic Perception Questionnair e scores and Zung questionnaire scores was the best predictor of ''ser ious'' back pain (P = 0.037), and the Modified Somatic Perception Ques tionnaire score was the best predictor of ''any'' back pain (P = 0.002 ). The 25% of participants with the highest sum of scores from the Mod ified Somatic Perception Questionnaire and Zung questionnaire was 2.7 times more likely to develop ''serious'' back pain than the 25% with t he lowest sum of these scores. Nevertheless, after accounting for the effects of a history of non-''serous'' back pain, psychometric scores predicted less than an additional 3% of reported back pain. Conclusion s. The scores from the Modified Somatic Perception Questionnaire and Z ung questionnaire were reproducible over 18 months and were affected l ittle by first episodes of back pain; yet these scores from these ques tionnaires precede back pain in a small number of people.