Jennifer Caffarel

The questionable benefit of multiple free-flow studies in men with lower urinary tract symptoms†

The diagnostic accuracy of maximum flow rate (Qmax) for bladder outlet obstruction (BOO) is limited. In a much-cited study, Reynard et al. concluded that diagnostic accuracy can be improved by taking the maximum Qmax of multiple flow rate measurements, observing that it may be more representative of the man’s usual Qmax. This conclusion was based on improved specificity from multiple voids. Yet this might also be achieved from a single void simply by lowering the threshold for classifying obstruction. We revisited the data published by Reynard et al. to compare diagnostic accuracy from the highest Qmax of multiple measurements, with that from a single measurement of Qmax.