Table 3.

Quantile Regression Models of Maximal Antibody Levels vs Bacillary Burden

	Regression Coefficients
Bacillary Burden	60th Quantile	70th Quantile	80th Quantile
Maximum antibody levels to any reactive protein
None (reference)
Low	−0.19 (−.49 to .61)	0.08 (−.40 to .82)	0.53 (−.08 to .89)
High	0.97 (.62–1.31)	0.97 (.69–1.25)	0.78 (.48–1.12)
Maximum antibody levels to any tuberculosis-associated protein
None (reference)
Low	0.66 (−.08 to 1.30)	0.83 (.31–1.63)	1.08 (.53–2.25)
High	2.47 (2.10–3.14)	2.74 (2.41–3.18)	2.61 (2.29–3.19)

Quantile regression was performed with maximum antibody levels to any reactive protein or tuberculosis-associated protein as dependent variable and burden class as independent variable. Regression coefficients (and 95% confidence intervals in parentheses) were calculated for the 60th, 70th and 80^th quantiles after adjusting for age, country of serum sampling, and history of past tuberculosis. Bacillary burden: none, nontuberculosis disease; low, sputum smear-negative tuberculosis; high, sputum smear-positive tuberculosis. The coefficients indicate antibody levels in either burden class compared with the no-burden class (reference). Differences between burden classes are significant (shown in bold) when the confidence intervals of coefficients do not include zero and when confidence intervals of 2 burden classes do not overlap.