Table 2.
Association of HBA gene copy number with CKD prevalence—analysis adjusted for all listed covariates
| Characteristic | CKDa (n=9908) Modified Poisson |
eGFR<60 ml/min per 1.73 m2 (n=1133) Modified Poisson |
Urine albumin-creatinine ratio >30 mg/g (n=1794) Modified Poisson |
||||||
|---|---|---|---|---|---|---|---|---|---|
| PR | 95% CI | P valueb | PR | 95% CI | P valueb | PR | 95% CI | P valueb | |
| HBA copy number, per gene copy | 1.14 | (1.07 to 1.21) | <0.0001 | 1.22 | (1.11 to 1.34) | <0.0001 | 1.09 | (1.02 to 1.18) | 0.01 |
| Sickle cell trait | 1.44 | (1.30 to 1.59) | <0.0001 | 1.29 | (1.09 to 1.51) | 0.006 | 1.56 | (1.38 to 1.77) | <0.0001 |
| APOL1 high-risk | 1.17 | (1.07 to 1.29) | 0.0007 | 1.16 | (1.00 to 1.35) | 0.06 | 1.26 | (1.12 to 1.40) | <0.0001 |
| Hemoglobin, per 1 g/dl | 0.90 | (0.87 to 0.92) | <0.0001 | 0.76 | (0.72 to 0.79) | <0.0001 | 0.93 | (0.89 to 0.97) | 0.00005 |
| Age, per year | 1.03 | (1.03 to 1.04) | <0.0001 | 1.07 | (1.06 to 1.07) | <0.0001 | 1.02 | (1.01 to 1.02) | <0.0001 |
| Female sex | 0.78 | (0.72 to 0.84) | <0.0001 | 0.74 | (0.65 to 0.84) | <0.0001 | 0.73 | (0.66 to 0.81) | <0.0001 |
| Body mass indexc | 1.08 | (1.05 to 1.12) | <0.0001 | 1.08 | (1.03 to 1.15) | 0.004 | 1.08 | (1.04 to 1.13) | 0.0003 |
| Hypertension | 1.86 | (1.66 to 2.07) | <0.0001 | 2.97 | (2.32 to 3.80) | <0.0001 | 1.82 | (1.57 to 2.11) | <0.0001 |
| Diabetes mellitus | 1.65 | (1.54 to 1.76) | <0.0001 | 1.36 | (1.22 to 1.52) | <0.0001 | 1.94 | (1.77 to 2.11) | <0.0001 |
| Smoking status | |||||||||
| Never (ref) | — | — | |||||||
| Past | 0.98 | (0.91 to 1.05) | 0.52 | 0.92 | (0.82 to 1.03) | 0.16 | 1.01 | (0.92 to 1.11) | 0.81 |
| Present | 1.29 | (1.17 to 1.43) | <0.0001 | 1.04 | (0.87 to 1.24) | 0.67 | 1.43 | (1.28 to 1.60) | <0.0001 |
| Medically insured | 0.91 | (0.81 to 1.04) | 0.16 | 1.10 | (0.86 to 1.43) | 0.44 | 0.85 | (0.74 to 0.98) | 0.03 |
| Region | |||||||||
| Non-belt (ref) | — | — | |||||||
| Belt | 0.97 | (0.90 to 1.05) | 0.45 | 0.99 | (0.88 to 1.11) | 0.81 | 0.93 | (0.85 to 1.02) | 0.13 |
| Buckle | 1.00 | (0.91 to 1.09) | 0.99 | 0.94 | (0.81 to 1.10) | 0.45 | 1.03 | (0.93 to 1.16) | 0.55 |
| Education level | |||||||||
| <HS grad (ref) | — | — | |||||||
| HS grad | 0.94 | (0.86 to 1.03) | 0.16 | 0.96 | (0.83 to 1.11) | 0.61 | 0.95 | (0.85 to 1.02) | 0.13 |
| Some college | 0.93 | (0.90 to 1.08) | 0.75 | 0.99 | (0.85 to 1.15) | 0.87 | 1.01 | (0.90 to 1.14) | 0.84 |
| ≥College grad | 0.92 | (0.82 to 1.02) | 0.29 | 1.07 | (0.90 to 1.27) | 0.42 | 0.90 | (0.79 to 1.04) | 0.15 |
| Income | |||||||||
| <$20K (ref) | — | — | |||||||
| $20K - $34K | 0.98 | (0.90 to 1.07) | 0.64 | 1.04 | (0.91 to 1.19) | 0.54 | 0.95 | (0.85 to 1.05) | 0.30 |
| $35K - $74K | 0.93 | (0.84 to 1.02) | 0.13 | 0.91 | (0.76 to 1.09) | 0.31 | 0.87 | (0.77 to 1.00) | 0.05 |
| ≥$75K | 0.75 | (0.63 to 0.90) | 0.0001 | 0.78 | (0.57 to 1.07) | 0.13 | 0.64 | (0.52 to 0.79) | <0.0001 |
All variables shown in the table were included in the multivariable model. Multiple imputations were performed for missing data. The number of participants available for this analysis was 9908. APOL1, apolipoprotein-L1; ref, reference category; –, reference category; HS, high school; grad, graduate; K, thousand.
a
CKD prevalence was defined by a urine albumin-creatinine ratio ≥30 mg/g or an eGFR<60 ml/min per 1.73 m2 at baseline.
b
Analysis was performed using a modified Poisson multivariable regression model employing a linear effect of HBA allele count on the log of the PR.
c
Body mass index was scaled by SD.