Table 1. Associations between residual DBS characteristics and call rate among DBS archived at the Michigan Neonatal Biobank between 1992 and 2008.
| Residual DBS characteristics | Overall (n = 399) | Sample Call Rate | p-val1 | |
|---|---|---|---|---|
| ≥ 99.0% (n = 339) | < 99.0% (n = 60) | |||
| Storage environments, n (%) | <0.001 | |||
| Uncontrolled environment2 | 101 (25%) | 54 (16%) | 47 (78%) | |
| Controlled environment3 | 298 (75%) | 285 (84%) | 13 (22%) | |
| Year DBS collected, n (%) | <0.001 | |||
| 1992 | 26 (7%) | 11 (3%) | 15 (25%) | |
| 1993 | 24 (6%) | 8 (2%) | 16 (27%) | |
| 1994 | 29 (7%) | 17 (5%) | 12 (20%) | |
| 1995 | 22 (6%) | 18 (5%) | 4 (7%) | |
| 1996 | 26 (7%) | 26 (8%) | 0 (0%) | |
| 1997 | 24 (6%) | 19 (6%) | 5 (8%) | |
| 1998 | 24 (6%) | 19 (6%) | 5(8%) | |
| 1999 | 32 (8%) | 31 (9%) | 1 (2%) | |
| 2000 | 16 (4%) | 16 (5%) | 0 (0%) | |
| 2001 | 25 (6%) | 25 (7%) | 0 (0%) | |
| 2002 | 28 (7%) | 28 (8%) | 0 (0%) | |
| 2003 | 17 (4%) | 15 (4%) | 2 (3%) | |
| 2004 | 8 (2%) | 8 (2%) | 0 (0%) | |
| 2005 | 24 (6%) | 24 (7%) | 0 (0%) | |
| 2006 | 33 (8%) | 33 (10%) | 0 (0%) | |
| 2007 | 14 (4%) | 14 (4%) | 0 (0%) | |
| 2008 | 27 (7%) | 27 (8%) | 0 (0%) | |
| Leukemia status, n (%) | 0.6 | |||
| Leukemia | 23 (6%) | 21 (6%) | 2 (3%) | |
| No leukemia | 376 (94%) | 318 (94%) | 58 (97%) | |
| Infant sex, n (%) | 0.6 | |||
| Male | 206 (52%) | 173 (51%) | 33 (55%) | |
| Female | 193 (48%) | 166 (49%) | 27 (45%) | |
| Maternal race/ethnicity, n (%) | 0.04 | |||
| Non-Hispanic White | 308 (77%) | 264 (78%) | 44 (73%) | |
| Non-Hispanic Black | 57 (14%) | 44 (13%) | 13 (22%) | |
| Non-Hispanic Asian | 13 (3%) | 10 (3%) | 3 (5%) | |
| Hispanic | 21 (5%) | 21 (6%) | 0 (0%) | |
| Total DNA yield in μg, median (range) | 5.3 (2.3–14.4) | 5.3 (2.4–14.4) | 4.8 (2.3–13.3) | 0.3 |
1Pearson chi-square, Fisher’s exact, or Wilcoxon rank-sum p-value comparing residual DBS characteristics by sample call rate.
2Uncontrolled temperature, 35% humidity.
370 degrees Fahrenheit, 35% humidity.