The Prolo Scale: history, evolution and psychometric properties

BACKGROUND: The Prolo Scale (PS) is a widely accepted assessment tool for lumbar spinal surgery results. Nevertheless, in the literature there is a dearth of consensus about its application, interpretation and accuracy. The purpose of this review is to investigate the evolution of the PS from its introduction in 1986 to the present, including an analysis of different versions of the scale and research on the existing studies investigating its psychometric properties. MATERIALS AND METHODS: PubMed, Cochrane Library and PEDro databases were searched. Studies in English, Italian, French, Spanish and German published from 1986 to December 2012 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 2 more subscales (pain and medication), and Davis adapted the scale for the cervical spine. PS is often mentioned without any specific reference to the version used; therefore, a homogeneous comparison of studies is difficult to achieve. Several authors agree on the need 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. CONCLUSIONS: The Prolo Scale has been adopted for clinical examination for 20 years because it is easy to administer and useful to compare significant amounts of data from surgical studies carried out at different times. Although several authors demonstrated the scale sensitivity among a battery of tests, no thorough validation study was found in the current literature.