Table 1.
Baseline characteristics of the NHANES (2007–2012) study population in SII tertiles.
| Characteristics | Total | Systemic immune-inflammatory index | p-Value | ||
|---|---|---|---|---|---|
| Tertile 1 (13.750–387.529) | Tertile 2 (387.545–596.077) | Tertile 3 (596.111–4085.000) | |||
| Numbers | 6,875 | 2,292 | 2,291 | 2,292 | |
| Age (years) | 46.87 ± 0.40 | 46.04 ± 0.55 | 47.07 ± 0.47 | 47.45 ± 0.53 | 0.064 |
| Sex | <0.001 | ||||
| Male | 49.81 (48.69, 50.93) | 53.86 (51.09, 56.60) | 50.57 (47.82, 53.32) | 45.22 (42.90, 47.57) | |
| Female | 50.19 (49.07, 51.32) | 46.14 (43.40, 48.91) | 49.43 (46.68, 52.18) | 54.78 (52.44, 57.10) | |
| Race | <0.001 | ||||
| Mexican American | 7.75 (5.98, 9.98) | 7.77 (6.12, 9.81) | 8.02 (6.02, 10.61) | 7.45 (5.47, 10.06) | |
| Non-Hispanic Black | 9.87 (7.72, 12.53) | 14.50 (11.38, 18.31) | 7.95 (6.20, 10.15) | 7.42 (5.58, 9.81) | |
| Non-Hispanic White | 71.74 (66.99, 76.05) | 67.75 (62.74, 72.39) | 72.23 (67.49, 76.53) | 75.00 (69.67, 79.66) | |
| Other Hispanic | 4.87 (3.52, 6.70) | 4.68 (3.45, 6.33) | 5.22 (3.68, 7.34) | 4.70 (3.17, 6.90) | |
| Other race | 5.78 (4.75, 7.02) | 5.30 (4.00, 6.98) | 6.58 (5.11, 8.43) | 5.44 (4.15, 7.11) | |
| Marital status | 0.006 | ||||
| Nonsingle | 64.14 (61.18, 67.00) | 66.31 (62.70, 69.74) | 65.18 (61.40, 68.78) | 61.05 (57.59, 64.39) | |
| Single | 35.86 (33.00, 38.82) | 33.69 (30.26, 37.30) | 34.82 (31.22, 38.60) | 38.96 (35.61, 42.41) | |
| Education level | 0.221 | ||||
| <High school | 5.77 (4.94, 6.72) | 5.79 (4.83, 6.93) | 6.11 (5.02, 7.43) | 5.39 (4.38, 6.63) | |
| Graduated from high school | 35.82 (32.65, 39.11) | 34.11 (30.50, 37.90) | 35.28 (32.30, 38.39) | 37.96 (33.04, 43.14) | |
| College education or above | 58.42 (54.84, 61.92) | 60.11 (56.24, 63.85) | 58.61 (54.94, 62.18) | 56.65 (51.40, 61.75) | |
| Family PIR | 3.05 ± 0.06 | 3.07 ± 0.07 | 3.14 ± 0.07 | 2.93 ± 0.08 | 0.010 |
| Family PIR groups | 0.004 | ||||
| <1 | 13.85 (12.06, 15.86) | 13.90 (11.95, 16.11) | 13.28 (11.19, 15.68) | 14.39 (12.21, 16.88) | |
| ≥1, <3 | 35.61 (32.73, 38.60) | 35.33 (31.71, 39.13) | 32.94 (29.66, 36.40) | 38.54 (34.96, 42.26) | |
| ≥3 | 50.54 (46.80, 54.28) | 50.77 (46.60, 54.93) | 53.78 (49.45, 58.05) | 47.07 (42.36, 51.83) | |
| Alcohol use | 0.406 | ||||
| Never | 10.38 (9.10, 11.82) | 11.26 (9.32, 13.55) | 9.21 (7.91, 10.70) | 10.73 (9.00, 12.75) | |
| Former | 16.14 (14.15, 18.35) | 14.79 (13.07, 16.70) | 16.43 (13.77, 19.48) | 17.12 (14.36, 20.29) | |
| Mild | 34.54 (31.96, 37.22) | 34.76 (31.39, 38.28) | 35.62 (32.53, 38.82) | 33.26 (29.23, 37.54) | |
| Moderate | 16.90 (15.33, 18.60) | 17.55 (15.21, 20.17) | 17.23 (15.33, 19.31) | 15.95 (13.29, 19.03) | |
| Heavy | 22.04 (20.47, 23.69) | 21.64 (19.21, 24.28) | 21.52 (19.35, 23.86) | 22.94 (20.70, 25.35) | |
| Smoking status | 0.002 | ||||
| Never | 53.26 (50.95, 55.57) | 56.11 (53.62, 58.57) | 53.32 (50.17, 56.44) | 50.53 (46.37, 54.68) | |
| Former | 25.19 (23.86, 26.55) | 24.46 (22.18, 26.88) | 26.84 (24.57, 29.24) | 24.21 (22.12, 26.43) | |
| Now | 21.55 (19.58, 23.66) | 19.44 (16.76, 22.42) | 19.84 (17.41, 22.52) | 25.26 (22.13, 28.67) | |
| BMI (kg/m2) | 28.67 ± 0.11 | 27.87 ± 0.19 | 28.69 ± 0.16 | 29.40 ± 0.20 | <0.001 |
| BMI groups | 0.010 | ||||
| ≤18.5 | 1.54 (1.15, 2.06) | 2.06 (1.36, 3.11) | 1.22 (0.78, 1.92) | 1.37 (0.88, 2.12) | |
| >18.5, ≤25.0 | 30.01 (28.35, 31.71) | 32.43 (29.64, 35.34) | 28.59 (25.92, 31.42) | 29.15 (26.33, 32.14) | |
| >25.0, ≤30.0 | 34.15 (32.47, 35.87) | 35.19 (32.13, 38.38) | 35.13 (32.33, 38.03) | 32.19 (29.42, 35.09) | |
| >30 | 34.31 (32.57, 36.08) | 30.33 (27.20, 33.65) | 35.06 (32.61, 37.59) | 37.29 (34.10, 40.59) | |
| Diabetes | 0.283 | ||||
| No | 86.34 (84.95, 87.62) | 86.86 (85.15, 88.40) | 86.91 (85.02, 88.60) | 85.27 (82.85, 87.40) | |
| Yes | 13.66 (12.38, 15.05) | 13.14 (11.60, 14.85) | 13.09 (11.40, 14.98) | 14.73 (12.60, 17.15) | |
| UIC (µg/L) | 382.75 ± 122.44 | 252.37 ± 35.44 | 222.54 ± 11.42 | 666.56 ± 357.35 | 0.290 |
| UIC groups | 0.560 | ||||
| <100 | 32.60 (30.96, 34.29) | 33.47 (30.45, 36.63) | 32.35 (29.35, 35.50) | 32.04 (29.64, 34.55) | |
| ≥100, <300 | 48.39 (46.31, 50.48) | 49.10 (46.37, 51.84) | 47.63 (44.28, 50.99) | 48.48 (45.83, 51.14) | |
| ≥300 | 19.01 (17.23, 20.92) | 17.43 (15.44, 19.62) | 20.02 (16.61, 23.94) | 19.47 (17.70, 21.38) | |
| HbA1c (%) | 5.60 ± 0.02 | 5.57 ± 0.02 | 5.60 ± 0.02 | 5.62 ± 0.03 | 0.238 |
| ALT (IU/L) | 26.19 ± 0.26 | 26.83 ± 0.48 | 26.46 ± 0.50 | 25.32 ± 0.47 | 0.071 |
| AST (IU/L) | 26.21 ± 0.26 | 27.25 ± 0.50 | 25.92 ± 0.43 | 25.51 ± 0.40 | 0.022 |
| Cr (mg/dL) | 0.88 ± 0.00 | 0.88 ± 0.01 | 0.88 ± 0.01 | 0.87 ± 0.01 | 0.383 |
| TC (mmol/L) | 5.10 ± 0.02 | 5.02 ± 0.03 | 5.16 ± 0.03 | 5.11 ± 0.03 | 0.009 |
| FT3 (pg/mL) | 3.18 ± 0.01 | 3.21 ± 0.01 | 3.18 ± 0.01 | 3.16 ± 0.01 | 0.002 |
| FT4 (ng/dL) | 0.80 ± 0.01 | 0.80 ± 0.01 | 0.79 ± 0.01 | 0.81 ± 0.01 | 0.044 |
| TT3 (nmol/L) | 1.79 ± 0.01 | 1.80 ± 0.02 | 1.80 ± 0.02 | 1.77 ± 0.02 | 0.139 |
| TT4 (µg/dL) | 7.84 ± 0.04 | 7.74 ± 0.06 | 7.79 ± 0.04 | 7.97 ± 0.05 | <0.001 |
| TSH (μIU/mL) | 2.04 ± 0.06 | 2.03 ± 0.04 | 2.03 ± 0.12 | 2.06 ± 0.09 | 0.925 |
| FT3/FT4 | 4.11 ± 0.03 | 4.14 ± 0.03 | 4.13 ± 0.03 | 4.06 ± 0.03 | 0.016 |
| TG (ng/mL) | 16.14 ± 0.57 | 14.83 ± 0.57 | 15.01 ± 0.81 | 18.52 ± 1.39 | 0.062 |
| TGAb (IU/mL) | 9.91 ± 1.04 | 11.19 ± 2.75 | 11.95 ± 2.58 | 6.65 ± 1.20 | 0.027 |
| TPOAb (IU/mL) | 21.65 ± 1.24 | 19.47 ± 2.12 | 20.31 ± 2.27 | 25.04 ± 2.64 | 0.236 |
Note: Continuous variables were presented as mean ± SEM, p-value was calculated by survey-weighted linear regression analysis. Categorical variables were presented as the percentage (95% confidence interval), p-value was calculated by survey-weighted chi-square test. NHANES, National Health and Nutrition Examination Survey; PIR, poverty income ratio; BMI, body mass index; UIC, urine iodine concentration; HbA1c, glycated hemoglobin; ALT, alanine aminotransferase; AST, aspartate aminotransferase; Cr, creatinine; TC, total cholesterol; FT3, free triiodothyronine; FT4, free thyroxine; TT3, total triiodothyronine; TT4, total thyroxine; TSH, thyroid-stimulating hormone; TG, thyroglobulin; TGAb, thyroglobulin antibodies; and TPOAb, thyroid peroxidase antibodies. Bold values signify the statistically significant variables clearly distinguishable from those that are not.