The Prolo Scale: history, evolution and psychometric properties

Background: Prolo Scale (PS) is a widely accepted assessment tool to evaluate lumbar spine surgery. However, a lack of consensus is reported in literature about its application, threefold values and validity. Purpose: The purpose of this review is to investigate the evolution of the Prolo Scale (PS) from its introduction in 1986 to the present, including an analysis of different versions of the scale and a research of the existing studies which investigated its psychometric properties. Matherials and Methods: The main electronic databases were searched between July and December 2012. Studies in English, Italian, French, Spanish and German published from1986 to 2011 were analyzed. Results: The original lumbar surgery outcome scale consisted of two Likert-type scales (Economic and Functional). There are three more versions of the scale: Schnee proposed one consisting of 10 items, Brantigan made one with 20 items and introduced two more subscales (Pain and Medication), Davis adapted the scale for cervical spine. Conclusion: The PS is often mentioned without any specific reference as to the version used, therefore a homogeneous comparison of studies is difficult to achieve. Several authors agree on the needing to embrace a multidimensional measuring system to evaluate Low Back Pain (LBP), but there is still no consensus regarding the most reliable tool. To date, PS has been mostly used as secondary outcome measure, in association with validated primary measures for LBP. The PS has been adopted for clinical examination for twenty years because it is easy-to-administer and useful to compare significant amount of data from surgical studies carried out at different times. Albeit several authors demonstrated the scale sensibility among a battery of tests, no thorough validation study was found in current literature.