Host iron redistribution as a risk factor for incident tuberculosis in HIV infection: an 11-year retrospective cohort study

Table 3 Host iron genotypes as a risk factor for incident tuberculosis in HIV infection

Iron genotypes	Model 1: IRR, unadjusted		Model 2: IRR, adjusted for known risk factors for TB*
	Is the iron genotype a risk factor for incident TB in HIV infection?		Does the iron genotype remain a risk factor for incident TB after adjusting for sex, baseline age, CD4, body mass index plus self-reported ethnicity?
Haptoglobin*
Hp 1-1	Reference		Reference
Hp 2-1, Hp 2-2	1.03 (0.68-1.56)	0.879	0.83 (0.47-1.49)	0.525
SLCA11A1
SLC1 (rs34448891) Allele 3/Allele 3	Reference		Reference
Allele 3/Other, Other/Other	0.96 (0.65-1.42)	0.832	1.29 (0.73-2.29)	0.377
SLC3 (rs3731865) G/G	Reference		Reference
C/G, C/C	1.05 (0.65-1.69)	0.853	1.56 (0.85-2.87)	0.151
SLC6a (rs17235409) G/G	Reference		Reference
A/G, A/A	0.95 (0.54-1.68)	0.869	1.10 (0.51-2.36)	0.813
SLC6b (rs17235416) TGTG +/+	Reference		Reference
TGTG +/-, -/-	0.90 (0.59-1.36)	0.610	1.00 (0.56-1.78)	0.996
CAAA (rs17229009) CAAA+/+, +/-	Reference		Reference
CAAA -/-	0.78 (0.49-1.25)	0.302	0.85 (0.45-1.61)	0.615

Main effects for iron-metabolism genotypes assessed using complete data with multiplicative Poisson regression models with differences estimated on a log scale and expressed as incidence rate ratios (IRR).
Absolute CD4 cell counts were natural-logarithm transformed; BMI was dummy-coded as <18.5 or ≥18.5 kg/m²; self-reported ethnicity was dummy-coded as Mandinka, Wolof, Fula, Jola or Otherwise.
*In this dataset, unadjusted Poisson regression analyses indicated sex (females) (IRR, 95% CI = 0.53, 0.38 to 0.73), and higher absolute CD4 (IRR, 95% CI = 0.56, 0.50 to 0.64) were associated with significantly lower risk of incident TB and body mass index < 18.5 (IRR, 95% CI = 2.02, 1.33 to 3.08) was associated with a higher risk of TB. Age (IRR, 95% CI = 1.02, 1.00 to 1.04) was not a direct risk factor for TB in this dataset, but age was forced in models as it is commonly associated with differential risk of TB in the literature.
CI = 95% confidence interval; IRR = incidence rate ratio; TB = tuberculosis (all forms).

ISSN: 1471-2334