Table 2. Trend in proportions of call rate by collection years among DBS archived at the Michigan Neonatal Biobank between 1992 and 2008.
| Storage environments | Year DBS collected | Total DBS collected | DBS proportion with call rate ≥ 99.0% | p-trend1 |
|---|---|---|---|---|
| Uncontrolled environment2 | 0.006 | |||
| 1992 | 26 | 0.42 | ||
| 1993 | 24 | 0.33 | ||
| 1994 | 29 | 0.59 | ||
| 1995 | 22 | 0.82 | ||
| Controlled environment3 | 1996 | 26 | 1.00 | 0.002 |
| 1997 | 24 | 0.79 | ||
| 1998 | 24 | 0.79 | ||
| 1999 | 32 | 0.97 | ||
| 2000 | 16 | 1.00 | ||
| 2001 | 25 | 1.00 | ||
| 2002 | 28 | 1.00 | ||
| 2003 | 17 | 0.88 | ||
| 2004 | 8 | 1.00 | ||
| 2005 | 24 | 1.00 | ||
| 2006 | 33 | 1.00 | ||
| 2007 | 14 | 1.00 | ||
| 2008 | 27 | 1.00 |
1Multivariable logistic regression model adjusted for DNA yield and maternal race/ethnicity.
2Uncontrolled temperature, 35% humidity.
370 degrees Fahrenheit, 35% humidity.