Diabetes as an increasingly common comorbidity among patient hospitalizations for tuberculosis in the USA

Abstract

Objective: Diabetes is a risk factor for active tuberculosis (TB). The purpose of this paper was to estimate the risk of hospitalization for TB with and without a secondary diagnosis of diabetes in groups with different ethnic backgrounds.

Research design and methods: We used the Nationwide Inpatient Sample from 1998 to 2011, identifying all patients with a primary diagnosis of TB and/or a secondary diagnosis of diabetes (type 1 or type 2) or HIV. Next, we performed logistic regression to investigate the association of diabetes status, HIV status, and race (and the interaction of diabetes and race) with the risk of hospitalization with a primary diagnosis of TB. We also included a time covariate, to determine whether potential risk factors changed during the study period.

Results: Controlling for HIV status, diabetes did not increase the odds of TB in white and black patients. However, in Hispanic and Asian/Pacific Islander patients, diabetes increased the odds of TB by a factor of 1.7 (95% CI 1.51 to 1.83). Asian/Pacific Islanders who had diabetes but not HIV experienced 26.4 (95% CI 23.1 to 30.1) times the odds of TB relative to the white males without diabetes or HIV. In addition, the percent of TB cases that belong to these high-risk groups (Asian/Pacific Islander/Hispanic diabetics) has more than doubled from 4.6% in 1998 to 9.6% in 2011.

Conclusions: In specific demographic groups, diabetes was a strong risk factor for hospital admissions for TB.

Keywords: Epidemiology; Glycemic Control; Tuberculosis.

Figure 1

Quarterly hospitalizations of patients diagnosed with primary TB (top) or primary TB and secondary diabetes (bottom) in the USA (NIS, 1998–2011). *Not adjusted for autocorrelation; adjusted slope is –153.2 cases/year (based on modeling the errors as an autoregressive process of order one). NIS, Nationwide Inpatient Sample; TB, tuberculosis.

Figure 2

Secondary diabetes admissions for white, black, Hispanic, and Asian/Pacific Islander populations in the National Inpatient Sample.

Figure 3

Yearly trends in percentage of admissions for primary TB cases that occurred in selected high-risk groups from 1992 to 2011: secondary diagnoses of HIV are falling, while secondary diagnoses of diabetes are rising. Cases were aggregated by year and broken down into categories based on HIV status, DM status, and race. All trends shown were tested based on a linear probability model and found to be statistically significant at the 0.001 level. DM, diabetes mellitus; TB, tuberculosis.

Figure 4

Estimated absolute incidence rates of primary TB admissions (per 10 000 total hospitalizations) by race category (Asian/Pacific Islander, Hispanic, black, white, other) and secondary disease status (diabetic, HIV, neither). Rates calculated from transforming model-based odds estimates into probability estimates. TB, tuberculosis.