Pulmonary impairment after tuberculosis and its contribution to TB burden

Abstract

Background: The health impacts of pulmonary impairment after tuberculosis (TB) treatment have not been included in assessments of TB burden. Therefore, previous global and national TB burden estimates do not reflect the full consequences of surviving TB. We assessed the burden of TB including pulmonary impairment after tuberculosis in Tarrant County, Texas using Disability-adjusted Life Years (DALYs).

Methods: TB burden was calculated for all culture-confirmed TB patients treated at Tarrant County Public Health between January 2005 and December 2006 using identical methods and life tables as the Global Burden of Disease Study. Years of life-lost were calculated as the difference between life expectancy using standardized life tables and age-at-death from TB. Years lived-with-disability were calculated from age and gender-specific TB disease incidence using published disability weights. Non-fatal health impacts of TB were divided into years lived-with-disability-acute and years lived-with-disability-chronic. Years lived-with-disability-acute was defined as TB burden resulting from illness prior to completion of treatment including the burden from treatment-related side effects. Years lived-with-disability-chronic was defined as TB burden from disability resulting from pulmonary impairment after tuberculosis.

Results: There were 224 TB cases in the time period, of these 177 were culture confirmed. These 177 subjects lost a total of 1189 DALYs. Of these 1189 DALYs 23% were from years of life-lost, 2% were from years lived-with-disability-acute and 75% were from years lived-with-disability-chronic.

Conclusions: Our findings demonstrate that the disease burden from TB is greater than previously estimated. Pulmonary impairment after tuberculosis was responsible for the majority of the burden. These data demonstrate that successful TB control efforts may reduce the health burden more than previously recognized.

Figure 1

Years of-life-lost (YLL), Years lived-with-disability-acute (YLD-Acute), Years lived-with-disability-chronic (YLD-Chronic) and Total Disability-Adjusted Life Years (DALY), for males and females. Total = YLL + YLD-Acute + YLD-Chronic.

Figure 2

Racial Distribution of TB burden stratified by age groups for the 177 culture confirmed Tuberculosis patients seen between January 1, 2005 and December 31, 2006, Tarrant County, Texas.

Figure 3

Sensitivity analysis: comparisons of the effects of varying the discount rates from 0 to 10%, on total TB Burden in DALY*. *Uniform age weights were applied throughout

Figure 4

Comparison of the effects of using Texas life-tables instead of the Japanese life-tables on total tuberculosis burden.