The high-low amputation ratio: a deeper insight into diabetic foot care?

The purpose of this study was to propose and evaluate a high to low (Hi-Lo) amputation ratio as a potential additional quality measure giving further insight into high-risk foot surveillance beyond foot screening examinations. As part of the Dartmouth Atlas of Health Care project, a secondary analysis was performed on Medicare administrative data. Amputation rates were adjusted for age, gender, and race. This included 37,808 minor (foot-level) amputations and 44,599 major amputations from 1996 to 1997. We also calculated the longitudinal national trends in the Hi-Lo ratio with data from the Centers for Disease Control and Prevention from 1992 to 2002. The adjusted mean Hi-Lo ratio was 1.35 (standard deviation, 0.42). The lowest ratio was 0.56, and the highest ratio was 3.43. The correlation coefficient for the Hi-Lo ratio with major amputation rate was 0.48 (P < .0001; R2 = 0.23). Similar correlations were found for the highest and lowest percentiles for major and minor rates. The Centers for Disease Control and Prevention data of the Hi-Lo ratio using the crude and age-adjusted rates suggest stable trends in the ratio over a decade. The Hi-Lo measure demonstrates face validity, yet only a small proportion of the variance is described by local propensity to perform major amputation or by major amputation rates alone. The United States has relied on a foot screening measure alone, perhaps explaining why major amputation rates have not substantively declined. If we are to reduce the amputation burden, we should begin with a straightforward measure that can be implemented at most any center.