Blackfoot Disease in Taiwan: A 30-Year Follow-up Study

Blackfoot disease is an endemic peripheral vascular disease found among the inhabitants of a limited area on the southwest coast of Tai wan, where artesian well water with a high concentration of arsenic has been used for more than eighty years. The natural history of blackfoot dis ease, based on a prospective study of 1,300 patients, is presented. The overall male/female ratio was 1.5:1. Although the clinical onset was usu ally insidious, it may be quite sudden and almost always begins with numb ness or coldness in one or more ex tremities, usually the feet. Ultimately, rest pain develops and progresses to gangrene. In this series, 68% of the patients underwent spontaneous or operative amputation, and the reamputation rate was 23.3%. Lower extremity in volvement in blackfoot disease was observed in 97.7% of the cases. The average annual rate for major ampu tation was 3.81 per 100 patient-years. The factors influencing the progno sis, such as amputation in relation to age and disease onset, are analyzed. The case fatality rate was 66.5% during thirty years; 44% of these were cardiovascular deaths. The an nual death rate was 4.84 per 100 pa tient-years. Other reported case fatality rates for vascular insuffi ciency are reviewed. A dose-response relationship between blackfoot dis ease and the duration of water intake was also noted. The survival rates af ter the onset of blackfoot disease were: five years, 76.0%; ten years, 59.5%; twenty years, 38.2%; thirty years, 28.6%. The 50% survival point was 13.5 years after onset of the dis ease.