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).