Table 3. Mixed-effects regression models of serum uric acid (SUA) by genetic risk score (GRS) tertiles (GRSbase and GRSrate: model A; GRStotal: model B), stratified by sex* (Regression coefficients (γ) with their standard errors of the estimate (SEE)).
| SUA | Total† | Men† | Women† | ||||||
|---|---|---|---|---|---|---|---|---|---|
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| n 766 | n′ 1341 | n 343 | n′ 583 | n 423 | n′ 758 | ||||
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| γ | SEE | P | γ | SEE | P | γ | SEE | P | |
| Model A: GRS base and rate | |||||||||
| Fixed effects | |||||||||
| GRS21base (γ021 for π0i) | +0.32 | 0.11 | 0.004 | +0.36 | 0.18 | 0.043‡ | +0.30 | 0.14 | 0.029 |
| GRS21rate × Time (γ121 for π1i) | +0.02 | 0.020 | 0.47 | +0.03 | 0.041 | 0.42 | +0.02 | 0.03 | 0.56 |
| GRS31base (γ031 for π0i) | +0.54 | 0.12 | <0.001 | +0.44 | 0.18 | 0.013‡ | +0.60 | 0.15 | <0.001 |
| GRS31rate × Time (γ131 for π1i) | +0.06 | 0.03 | 0.037 | +0.11 | 0.05 | 0.021‡ | +0.004 | 0.039 | 0.90 |
| Model B: GRS total | |||||||||
| Fixed effects | |||||||||
| GRS21total (γ021 for π0i) | +0.31 | 0.11 | 0.007 | +0.40 | 0.18 | 0.022 | +0.23 | 0.15 | 0.12 |
| GRS21total × Time (γ121 for π1i) | +0.01 | 0.03 | 0.73 | +0.02 | 0.05 | 0.61 | +0.02 | 0.03 | 0.56 |
| GRS31total (γ031 for π0i) | +0.50 | 0.12 | <0.001 | 0.44 | 0.19 | 0.020 | +0.56 | 0.16 | 0.001 |
| GRS31total × Time (γ131 for π1i) | +0.04 | 0.03 | 0.20 | 0.01 | 0.05 | 0.81 | +0.03 | 0.04 | 0.36 |
n, number of participants in the analysis; n′, total number of visits included in the analysis; Agebase, baseline age at visit 1; GRS21, High Serum Uric Acid Risk Score dummy for tertile 2 v. tertile 1; GRS31, High Serum Uric Acid Risk Score dummy for tertile 3 v. tertile 1.
Random effects are not shown for simplicity.
Models were further adjusted for marital status, poverty status, education (years), baseline current smoking status, current illicit drug use and baseline BMI centred at 30 kg/m2, the ten principal components for population structure, other dietary factors namely total grains, total fruit, total vegetables, other meats, discretionary solid fat and discretionary oils, and the inverse Mills ratio. Agebase was centred at 50 years, sex was coded as 0 = women, 1 = men. All dietary factors were centred at their weighted means (see Table 1, total). Tertiles of GRSbase had the following distribution: T1 (N 258, mean 7.80, sd 1.95, range 2–10); T2 (N 279, mean 11.76, sd 0.94, range 10–13); T3 (N 229, mean 15.18, sd 1.28, range 13–19). Tertiles of GRSrate had the following distribution: T1 (N 325, mean 0.68, sd 0.46, range 0–1); T2 (N 291, mean 1.85, sd 0.34, range 1–2); T3 (N 150, mean 2.88, sd 0.61, range 2–5). See Table 4 for ranges and mean values and standard deviations of GRStotal within its tertiles.
P<005 for interaction with sex to test effect modification by sex for each of the two dummy variables (i.e. GRS21 and GRS31) on SUA at baseline and SUA change over time.