PREDICTING LONG-TERM DISABILITY IN LOW-BACK INJURED WORKERS PRESENTING TO A SPINE CONSULTANT

Low back pain (LBP) is the most common, costly, and disabling muscoloskeletal condition. Although most LBP patients recover within two months, 2-3% eventually develop disabling chronic low back pain (DCLBP). Due to the prevalence of DCLBP problems, models have been developed to predict which acute low back pain patients are predisposed to the problems associated with this condition. Many see the development of these models as a first step that must be taken before useful approaches for containing and reducing the problem can be conceptualized, implemented, and tested. A recent publication by Cats-Baril and Frymoyer6 considered this specific problem. While the results of their study indicate considerable success in predicting DCLBP patients, the high prediction rates they obtained may be spurious because of the characteristics of their sampled patient population in conjunction with some of the predictors they found useful in identifying DCLBP patients. The purpose of the present study was to focus on the crucial patient population (i.e., acute LBP patients who perceive their problem as work-related and who have been unable to work for more than two but less than six weeks), and evaluate the ability of various personal, medical, occupational, and psychological factors to predict predisposition to DCLBP. Fifty-five patients referred by occupational physicians were evaluated and followed successfully for at least 6 months. Patients in the study were given a physical examination that included Spratt et al's assessment of pain behavior-24 They were then asked to fill out an extensive battery of self-report questionnaires, addressing issues associated with personal demographics, health history, work requirements, job satisfaction, injury information, and pain/function factors. At the 6-month follow-up, a structured telephone interview was used to obtain outcome information regarding patient status, including ability to return to work and general outcomes of treatment. Average patient age was 37.2 years (range, 22-57) and 67% of the patients were male. On average, patients had been unable to work for approximately 4 weeks when initially surveyed. Overall, 12.7% of the patients returned to work within 1 month of injury, 40% returned within 2 months, 54.5% within 3 months, 69% within 4 months, 74.5% within 5 months, 76.3% within 6 months, 80% within 7 months, and 83.6% after 7 months. .Approximately 16% never successfully returned to work within the follow-up period of this study. DCLBP was found to be correlated only with marital status, as married patients returned to work more quickly than single patients (P< 0.01). No significant correlation was found between DCLBP and personal demographics, health factors, work-related variables, or pain and function variables. Explanations for the overall inability to predict accurately the recovery times and/or rates of long-term disability in this patient population are suggested. When isolating realistic cases where predicting which patients presenting with acute low back troubles are likely to become chronic cases, the optimal prediction equation would appear to be: Perception that low back trouble is work-related + absence from work for more than 2 weeks = High Risk Case.