Successful Pulsed Radiofrequency for Lumbosacral Radicular Pain: Not So Easy to Predict

Dear Editor, Van Boxem et al. [1] have identified predictors of significant pain reduction at 6 months after pulsed radiofrequency (PRF) for lumbosacral L5/S1 radiculopathies. Predicting the outcomes of chronic pain therapies is a difficult task and we would like to commend the authors for being able to extract and present multiple factors contributing to successful PRF. However, we have some statistical and theoretical issues to raise. First, while the authors’ multivariate analysis reported three seemingly independent parameters, there may still be outstanding confounding factors that need to be addressed. The first problem is the negative value of the odds ratio (OR) of the Oswestry Disability Index. The OR is the ratio of the odds of an event occurring in one exposed (or treated or with a specific property) group to the odds of it occurring in another nonexposed group, and can take only positive values (above 0): when OR is close …