Srabashi Basu

Variation in the Incidence and Proportion of Diabetes-Related Amputations in Minorities

OBJECTIVE To identify the age-adjusted and level-specific incidence of amputations associated with diabetes in Hispanics, African-Americans, and non-Hispanic whites. RESEARCH DESIGN AND METHODS We used a database from the Office of Statewide Planning and Development in California that identified all hospitalizations for lower-extremity amputations in the state in 1991. Amputation level was defined by ICD-9-CM codes 84.11–84.18 and were categorized as toe, foot, leg, and thigh amputations. RESULTS The age-adjusted incidence of diabetes-related amputation per 10,000 persons with diabetes in 1991 was 95.25 in African-Americans, 55.98 in non-Hispanic whites, and 44.43 in Hispanics. Hispanics had a higher proportion of amputations (82.7%) associated with diabetes than did African-Americans (61.6%) or non-Hispanic whites (56.8%) (P < 0.001). African-Americans had the highest age-adjusted incidence rate for each level in people with and without diabetes. African-Americans underwent more proximal amputations compared with non-Hispanic whites and Hispanics (P < 0.001). Diabetes-related amputations were 1.72 and 2.17 times more likely in African-Americans compared with non-Hispanic whites and Hispanics, respectively. CONCLUSIONS Hispanics had proportionally more amputations associated with diabetes than did African-Americans or non-Hispanic whites. A significant excess incidence of both diabetes- and non-diabetes-related amputations and proportionally more proximal amputations were identified in African-Americans compared with Hispanics and non-Hispanic whites. A possible explanation could be the higher prevalence of peripheral vascular disease in African-Americans. Public health initiatives, which have been demonstrated to reduce the incidence of diabetes-related lower-extremity amputations, should be implemented, and additional work should focus on minority groups.

Survival among Mexican-Americans, non-Hispanic whites, and African-Americans with end-stage renal disease: the emergence of a minority pattern of increased incidence and prolonged survival.

We undertook this study to determine whether there is a significant difference in survival on treatment for end-stage renal disease between Mexican-Americans, non-Hispanic whites, and African-Americans. A database covering the years 1975 to 1986 was obtained from the Texas Kidney Health Program. Eight-eight percent to 90% of patients starting renal replacement therapy in Texas were included in this database. The patients were followed until death, for 3 years after successful transplantation, or until they were lost to follow-up. Life table analysis as well as age-adjusted analysis using the Cox proportional hazards model were performed comparing ethnic/racial groups, disease etiology, and treatment type. In life-table analyses, African-Americans and Mexican-Americans had a survival advantage in most age, disease, and treatment groups. With age adjustment, this survival advantage remained for all etiologies combined, for diabetes and hypertension cases, and for patients receiving hemodialysis in a center. Multivariate analysis revealed a persistent survival advantage for Mexican-Americans independent of traditional predictor variables, such as age, disease etiology, treatment type, or size of the center in which they received treatment. In this same analysis, African-Americans showed an advantage in the older age groups. Both African-Americans and Mexican-Americans on renal replacement therapy have an increased survival advantage compared with non-Hispanic whites. Given the additional burden of increased incidence of end-stage renal disease in these groups, the cost of renal replacement therapy for these minorities is disproportionately high. Further study should be aimed at elucidation of the mechanisms by which minorities achieve their survival advantage.

Tests of hypotheses in discrete models based on the penalized Hellinger distance

Analogues of the likelihood ratio, Rao, and Wald tests are introduced in discrete parametric models based on the family of penalized Hellinger distances. It is shown that the tests based on a particular member of this family provide attractive alternatives to the tests based on the ordinary Hellinger distance. These tests share the robustness of the Hellinger distance test, but are often closer to the likelihood-based tests at the model, especially in small samples. The convergence of ordinary Hellinger distance tests to limiting [chi]2 distributions are quite slow. The proposed tests are improvements in this respect.

Robust minimum distance inference based on combined distances

The minimum disparity estimators proposed by Lindsay (1994) for discrete models form an attractive subclass of minimum distance estimators which achieve their robustness without sacrificing first order efficiency at the model. Similarly, disparity test statistics are useful robust alternatives to the likelihood ratio test for testing of hypotheses in parametric models; they are asymptotically equivalent to the likelihood ratio test statistics under the null hypothesis and contiguous alternatives. Despite their asymptotic optimality properties, the small sample performance of many of the minimum disparity estimators and disparity tests can be considerably worse compared to the maximum likelihood estimator and the likelihood ratio test respectively. In this paper we focus on the class of blended weight Hellinger distances, a general subfamily of disparities, and study the effects of combining two different distances within this class to generate the family of “combined” blended weight Hellinger distances, a...

Improving precision through modelling: an illustration with hierarchical kappa

In this paper we consider a model based approach for estimating hierarchical kappa statistics to demonstrate improved precision through modelling. An extensive simulation study shows the improvement over the classical estimates due to model smoothing in terms of reduced mean square error