Background Prediction modelling research consists out three major phases, including: (1) developing and internally validating a prediction model; (2) external validation; (3) assessing the model's impact on patients outcomes and clinical decision making . Of the few published referral rules (e.g. prediction models) for axial spondyloarthritis (axSpA), only one is recently externally validated in the CaFaSpA 2 study (CAse Finding Axial SPondyloArthritis) . This referral rule has shown to be effective and discriminative in identifying patients with axSpA. Since this referral rule can potentially improve clinical decision making, it is worthwhile to perform an impact analysis to determine its effect in clinical practice.
Objectives To evaluate the clinical impact of the CaFaSpA referral rule in young patients with chronic low back pain (CLBP) presenting at the general practioner (GP).
Methods The study population are CLBP patients, ages 18-45 years, registered by the ICPC code L03 in the database of their GPs. The design of the study is a stratified prospective cluster randomized trial. The GP practices are the clusters and will be randomized to either a control group wherein usual care according to the Dutch guidelines for low back pain (LBP) will be used, or an intervention group; using the CaFaSpA referral rule. The CaFaSpA referral rule consists out four variables, the ASAS inflammatory back pain questionnaire, a family history for spondyloarthritis, reaction to NSAIDs and LBP duration ≥5 years. If at least two of these four variables are present, the risk of axSpA is increased and referral to the rheumatologist is advised.
All patients will be asked to fill in several questionnaires at different time points, baseline, 4, 12 and 24 months. The questionnaires comprises questions on the degree of back pain, clinical features, quality of life and health care costs, including work productivity.
Results The primary clinical outcome is a change in the score of the Roland Morris Disability Questionnaire (RMDQ) at 4 months compared to baseline, between the intervention and the usual care group. Secondary endpoints include, back pain intensity (VAS-pain), health related quality of life (SF-36 and EQ-5D), fear avoidance beliefs (Tampa scale for kinesiofobia and Fear avoidance beliefs questionnaire), levels of anxiety and depression (HADS questionnaire) and the impact on work (iPCQ) and health-care resources use and costs (iMCQ). Finally the percentage of referred patients and final diagnosis of axSpA will be investigated. The sample size had been estimated to 834 patients, taking into account lost to follow up and the design effect of a cluster randomized trial. After approval from the Medical Ethical Committee, it is expected that the IMPACT study will start at April 2014.
Conclusions If the final goal of a prediction model is to be incorporated into the daily practice, an impact study is inevitable. Therefore we want to perform the IMPACT study to investigate the clinical impact of the CaFaSpA referral rule in young primary care patients with CLBP.
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Disclosure of Interest None declared
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