Value of predictive instruments to determine persisting restriction of function in patients with subacute non-specific low back pain. Systematic review.

Low back pain (LBP) can restrict function with all the personal, interpersonal, and social consequences, such as a loss of independence and the inability to fulfil diverse roles in social life. Therefore, the prevention of the consequences of LBP would reduce costs, individual burdens and social burdens. Being able to fulfil the requirements of daily living is a cornerstone of quality of life. Early identification of patients who are likely to develop chronic pain with persistent restricted function is important, as effective prevention needs informed allocation of health care and social work. The aim of this study was to report and discuss the predictive value of instruments used to identify patients at risk of chronic LBP. Medline, Embase, CINAHL, Central, PEDro, Psyndex, PsychInfo/PsycLit, and Sociofile were systematically searched up to July 2004. Reference lists of systematic reviews on risk factors, and reference lists of the studies included were also searched. The selected studies evaluated predictive values of tools or predictive models applied 2-12 weeks after an initial medical consultation for a first or a new episode of non-specific LBP with restriction in function. Instruments had to predict function-related outcomes. Because of the heterogeneity of the instruments used we did not pool the data. Sixteen publications on function-related outcomes were included. The predictive instruments in these studies showed only moderate ability to predict or explain function-related outcome (maximal 51% of the variability). There was great variability in the predictors included and not all known risk factors were included in the models. The reviewed tools showed a limited ability to predict function-related outcome in patients with risk of chronic low back pain. Future instruments should be based on models with a comprehensive set of known risk factors. These models should be constructed and validated by international, coordinated research teams.