Factors associated with diabetes in tuberculosis patients in Harris County, Texas 1995--2004

Objective. To determine the prevalence and factors associated with diabetes in tuberculosis patients in Harris County, Texas. ^ Background. Tuberculosis and diabetes mellitus are two diseases of immense public health significance. Various epidemiologic studies have established an association between the two conditions. While many studies have identified factors associated with the conditions individually, few have looked at factors associated with their co-occurrence particularly in the United States. Furthermore, most of those studies are hospital-based and may not be representative of the population. The aim of this study was to determine the prevalence and distribution of diabetes among tuberculosis patients in Harris County, Texas and to identify the factors associated with diabetes in tuberculosis. ^ Methods. A population-based case control study was performed using secondary data from the Houston Tuberculosis Initiative (HTI) collected from October 1995 to September 2004. Socio-demographic characteristics and clinical variables were compared between tuberculosis patients with diabetes and non-diabetic tuberculosis patients. Logistic regression analysis was performed to identify associations. Survival at 180 days post tuberculosis diagnosis was assessed by Cox regression. ^ Results. The prevalence of diabetes among the tuberculosis (TB) population was 14.4%. The diabetics (cases) with a mean age 53 ± 13.3 years were older than the non-diabetics (controls) with a mean age of 39 ± 18.5 years (p\u3c0.001). Socio-demographic variables that were independently associated with the risk of diabetes were age (OR 1.04, p\u3c0.001) and Hispanic ethnicity (OR 2.04, p\u3c0.001). Diabetes was associated with an increased risk of pulmonary tuberculosis disease (OR 1.33, p\u3c0.028). Among individuals with pulmonary TB, diabetes was associated with positive sputum acid-fast bacilli (AFB) smear (OR 1.47, p\u3c0.005) and culture (OR 1.83, p\u3c0.018). Diabetics were more likely to have cavitary lung disease than non-diabetics (OR 1.50, p\u3c0.002). After adjustment for age and HIV status, the risk of dying within 180 days of TB diagnosis was significantly increased in the diabetics (HR 1.51, p\u3c0.002). ^ Conclusion. Diabetes mellitus was more prevalent in our tuberculosis patients than in the general population. The tuberculous diabetic may be more infectious and has a higher risk of death. It is therefore imperative to screen diabetics for TB and TB patients for diabetes.