In a recent article in this Journal, Holland et al. correlate TB incidence in the United States since 1952 with time, immigration, and HIV in the late 1980s and early 1990s.1 The authors also correlate proportional decreases in TB incidence in 2008–2009 with increases in unemployment in 2009–2010 in a separate linear regression in which lagged unemployment explains about 10% of state variance in TB incidence (R2 = 0.10). Given the disparities in TB incidence trends comparing US-born versus foreign-born persons in the United States,2 these models may be enhanced by considering origin of birth as an explanatory or stratification variable.
Provisional national surveillance data as of 26 February 2011 show a continued decline in TB case counts, to 11 181 cases in 2010 compared with 11 531 cases in 2009.3 In provisional data, the proportion of all TB patients with cavitary disease was 26% in 2009 and 25% in 2010, while 2% of patients were dead at diagnosis in both years. Despite the aberrant decline in 2009, these data suggest no increase in the number or severity of cases in 2010. As the 2010 case count data are finalized, we continue to investigate and be vigilant for any resurgence in TB. To date, none has been observed.
References
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