Seeking a Credible Basis for Prostatic Obstruction as the Reversible Cause of Other Lower Urinary Tract Dysfunctions

Lower urinary tract symptoms (LUTS) and various lower urinary tract dysfunctions (LUTDs) often coexist because their prevalence increases with ageing. In men, benign prostatic obstruction (BPO) is often proposed as a cause of other "secondary" LUTDs. However, causality of BPO in LUTDs, other than voiding LUTS and acute urinary retention, is probably indirect, if present at all. Indirect mechanisms complicate the inference of causality and may reduce the chance of reversibility. BPO is not a unifying explanation for LUTD, but one possible aetiological factor among many age-related, metabolic, neurological, behavioural, and anatomical factors. This mini-review discusses how to evaluate whether associations between BPO and LUTD are causal, reversible, and relevant to treatment decisions. The Bradford Hill viewpoints (strength, consistency, specificity, temporality, biological gradient, plausibility, coherence, experiment, and analogy) remain a useful framework for considering whether observed associations may be causal. However, the potential surgical setting of BPO adds two additional dimensions. First, is BPO needed to maintain the phenotype, such that treating BPO should bring resolution of the secondary problem? Second, if causation appears to apply at a population level, how confidently can that inference be applied to the individual man considering surgery? Association should not be mistaken for causation, causation should not be mistaken for reversibility, and reversibility should not be mistaken for sufficient net benefit for the individual man considering surgery.