過活動膀胱の医療経済

Abstract

Overactive bladder (OAB) is characterized by involuntary contractions of the detrusor muscles of the bladder. The primary symptoms of OAB include urinary urgency and frequency, with or without urge incontinence. Despite the growing awareness of OAB as a chronic medical condition, little is known about the disease's economic burden. Therefore, in the present study, the costs associated with the management of OAB symptoms in Japan were estimated, and the potential cost saving by increasing the rate of physician visits in OAB population was analyzed. To estimate the costs of OAB symptoms in Japan, we collected a variety of epidemiologic and economic literatures about OAB or urinary incontinence published by June, 2007. Three types of costs were considered in this estimation: 1. OAB treatment cost (pharmacological treatment cost, diagnostic cost and cost for physician visits), 2. direct cost (OAB-related cost [urinary tract infections, skin infections and fractures] and incontinence care cost [costs of pads, diapers and cleaning]), and 3. indirect cost (work loss due to absence from work and decrease in productivity). The analysis was conducted on community dwelling Japanese persons aged > or = 40 years, and assumed that OAB patients visited a hospital or a clinic once every four weeks. For the estimation of pharmacological treatment cost, four anticholinergic drugs (immediate-release oxybutynin (Pollakisu), propiverine (BUP-4), extended-release tolterodine (Detrusitol) and solifenacin (Vesicare)) were referred. Potential cost saving was estimated on the assumption that the hospital visit rate would increase from the current 22.7% to 35% and 50%, respectively. The number of persons with OAB symptoms and OAB patients was estimated at 8.6 million (4.6 million men, 4.0 million women) and 2.0 million (1.7 million men, 0.3 million women), respectively. The annual cost for OAB was estimated to be 956.2 billion yen (112,000 yen per one person with OAB symptoms). This cost included 180.9 billion yen (19%) for OAB treatment cost (including medication of 159.1 billion yen), 62 billion yen (6%) for OAB-related cost, 28.7 billion yen (3%) for incontinence care cost and 684.6 billion yen (72%) for work loss. Therefore, the cost for work loss accounted for the majority of OAB cost. The potential annual cost saving was estimated at 92.7 billion yen and 205.8 billion yen for the assumed hospital visit rate of 35% and 50%, respectively, and 88,000 yen per newly visiting OAB patient. It was revealed that the economic impact imposed by OAB was enormous. It might be possible to reduce the cost for OAB by appropriate treatment for OAB population.