Table 1.
Baseline characteristics of immune function substudy participants and all NECAT participants, by treatment group
| Immune Function Substudy Participants | All NECAT Participants* | |||
|---|---|---|---|---|
| N=59 | N=534 | |||
| Amalgam | Composite | Amalgam | Composite | |
| n=29 | n=30 | n=267 | n=267 | |
| Site, N (%) | ||||
| Boston | 11 (37.9) | 14 (46.7) | 144 (53.9) | 147 (55.1) |
| Maine | 18 62.1) | 16 (53.3) | 123 (46.1) | 120 (44.9) |
| Carious surfaces, mean (SD) [range] | 7.8 (5.2) [2–17] | 10.1 (6.3) [2–27] | 9.8 (6.9) [2–39] | 9.3 (6.2) [2–36] |
| Age (mean, SD) | 8.1 (1.3) | 8.0 (1.4)] | 7.9 (1.3) | 7.9 (1.4) |
| Gender, N (%) | ||||
| Female | 10 (34.5) | 19 (63.3) | 131 (49.1) | 156 (58.4) |
| Male | 19 (65.5) | 11 (36.7) | 136 (50.9) | 111 (41.6) |
| Race†, N (%) | ||||
| Non-Hispanic White | 26 (89.7) | 27 (90.0) | 165 (64.0) | 158 (60.3) |
| Non-Hispanic Black | 1 (3.5) | 1 (3.3) | 49 (19.0) | 49 (18.7) |
| Hispanic | 0 (0) | 0 (0) | 15 (5.8) | 23 (8.8) |
| Other | 2 (6.9) | 2 (6.7) | 29 (11.2) | 32 (12.2) |
| Household income, N (%) | ||||
| ≤ $20,000 | 5 (18.5) | 10 (33.3) | 74 (29.2) | 86 (33.1) |
| $20,001 – $40,000 | 14 (51.9) | 13 (43.3) | 113 (44.7) | 109 (41.9) |
| > $40,000 | 8 (29.6) | 7 (23.3) | 66 (26.1) | 65 (25.0) |
| Education of primary caretaker, N (%) | ||||
| < High school | 5 (17.2) | 7 23.3) | 34 (13.2) | 38 (14.6) |
| High school graduate | 23 (79.3) | 22 73.3) | 197 (76.4) | 194 (74.3) |
| College graduate | 1 (3.5) | 1 (3.3) | 27 (10.4) | 29 (11.1) |
| Ever had asthma, N (%) | ||||
| Yes | 6 (20.7) | 5 (16.7) | 50 (19.4) | 33 (12.6) |
| No | 23 (79.3) | 25 (83.3) | 208 (80.6) | 229 (87.4) |
| Ever had allergies, N (%) | ||||
| Yes | 4 (13.8) | 5 (16.7) | 38 (14.7) | 31 (11.8) |
| No | 25 (86.2) | 25 (83.3) | 220 (85.3) | 231 (88.2) |
| Hair mercury concentration, mean (SD) [range], ng/mg hair | 0.4 (0.3) [0.1–1.1] | 0.4 (0.5) [0.1–1.1] | 0.4 (0.5) [0.1–4.4] | 0.4 (0.5) [0.1–4.5] |
| Blood lead concentration, mean (SD) [range], μg/dl | 1.9 (1.4) [1–7] | 2.2 (1.4) [1–6] | 2.4 (1.9) [1–13] | 2.3 (1.5) [1–11] |
*
The number for all NECAT participants includes those who later withdrew (85 of 534). For race, lead, asthma and allergy, data were available for 520 participants; for income, 513; for education and hairy mercury, 519.
†
Race was self-reported by the parents of the children. The other category included individuals who identified themselves as Asian, Pacific Islander, Native American, biracial or other, which they were asked to specify.