Epidemiology and etiology of benign prostatic hyperplasia and bladder outlet obstruction.

Benign prostatic hyperplasia (BPH) is a histological diagnosis associated with unregulated proliferation of connective tissue, smooth muscle and glandular epithelium. BPH may compress the urethra and result in anatomic bladder outlet obstruction (BOO); BOO may present as lower urinary tract symptoms (LUTS), infections, retention and other adverse events. BPH and BOO have a significant impact on the health of older men and health-care costs. As the world population ages, the incidence and prevalence of BPH and LUTS have increased rapidly. Although non-modifiable risk factors - including age, genetics and geography - play significant roles in the etiology of BPH and BOO, recent data have revealed modifiable risk factors that present new opportunities for treatment and prevention, including sex steroid hormones, the metabolic syndrome and cardiovascular disease, obesity, diabetes, diet, physical activity and inflammation. We review the natural history, definitions and key risk factors of BPH and BOO in epidemiological studies.