Elderly Americans are at increased risk for having a leg or foot amputated, according to a study by researchers at Northwestern University Medical School and the Institute for Health Services Research and Policy Studies at Northwestern University.
Results of their study linked the recently escalating amputation rate to the undiminished prevalence of diabetes, which heightens risk for advanced vascular disease and diabetes-related complications, such as leg ulcers.
The increased number of amputations also was related to limited growth in hospitals' capacity to perform lower-extremity bypass surgery and angioplasty.
The amputation study, which was funded by the U.S. Agency for Health Care Policy and Research, appears in the August issue of the American Journal of Public Health.
Joe Feinglass, research associate professor of medicine, and colleagues at Northwestern and at the University of Chicago examined population-based rates of above- and below-the-knee amputation procedure for Americans by age, sex and other factors between 1979 and 1996.
They found that amputation rates rose at the beginning of the study period but were initially reversed in the mid-1980s following the introduction of lower-extremity bypass surgery and the ongoing decline in the prevalence of hypertension, ischemic heart disease and smoking.
However, by the mid-1990s, even with the advent of endovascular stents, thrombolytic therapy, new imaging technology and improved antibiotics, the downward trend flattened out and amputation rates began rising again.
"In 1988 to 1989, large increases in lower-extremity angioplasty procedures were accompanied by a temporary spike in the rate of bypass procedures. After 1993 to 1994, major amputation rates increased significantly while lower-extremity bypass procedures increased more modestly, consistent with relatively fixed hospital vascular surgery capacity," Feinglass said.
The researchers found that by 1996, the frequency of above- and below-the-knee amputation had increased from a 17-year average of 54,000 to 76,000 -- an 11 percent increase in age-adjusted rates from 1979-80 to 1995-96. It is estimated that 40 to 60 percent of above- and below-the-knee amputations involved patients with diabetes mellitus.
Men had over 70 percent higher above-the-knee and 45 percent higher below-the-knee amputation rates than women.
"Resolving the paradox of increasing amputation rates in the face of improved medical and surgical care will require a closer examination of the frequency and circumstances of primary amputation rates in the United States," Feinglass said.
The most important predisposing risk factors for lower-extremity vascular disease are male gender, advanced age, smoking, coronary heart disease, diabetes, severe hypertension and high cholesterol levels. Feinglass's co-researchers on this study were Jacqueline L. Brown, M.D., clinical instructor and faculty development fellow in general internal medical; Anthony LoSasso, research professor; Larry M. Manheim, research scientist and professor; Sanjiv J. Shah; and William H. Pearce, M.D., professor of surgery, of Northwestern University Medical School. LoSasso and Manheim also are with the Institute for Health Services Research and Policy Studies at Northwestern University. Also collaborating was Min-Woon Sohn of the University of Chicago.
This study also was supported by a grant from the National Heart, Lung, and Blood Institute.
Journal
American Journal of Public Health