Table 2.
Characteristics of the study population from Four Memorial Care Hospitals in Southern California
| Matched memorial care data | Unmatched Memorial Care data | p-value* | Matched birth certificate data | Unmatched birth certificate data | p-value** | ||
|---|---|---|---|---|---|---|---|
| Valid matching variables | Missing matching variables | Valid matching variablesa | |||||
| N | 62200 | 4162 | 6138 | 62200 | 9312 | ||
| Rate of preeclampsia (2001–2006 data) | 3.13 | 3.73 | 4.12 | <0.01 | 1.38 | 1.97 | <0.01 |
| Rate of preeclampsia (2001–2005 data) | 3.12 | 3.70 | 4.12 | <0.01 | 1.34 | 1.75 | <0.01 |
| Rate of preeclampsia (2006 data only) | 3.13 | 3.90 | N.A. | 0.41 | 1.57 | 2.23 | <0.01 |
| Rate of total diabetes (2001–2005 data) | 5.56 | 6.65 | 5.46 | 0.17 | 1.97 | 2.11 | 0.40 |
| Rate of total diabetes (2006 data only) | 6.93 | 7.20 | N.A. | 0.35 | 2.24 | 3.67 | <0.01 |
| Rate of gestational diabetes (2006 data only) | N.A. | N.A. | N.A. | 1.62 | 2.57 | 0.01 | |
| Rate of chronic diabetes (2006 data only) | N.A. | N.A. | N.A. | 0.62 | 1.10 | 0.04 | |
| Maternal ageb (%) | <0.01 | <0.01 | |||||
| <20 | 6.62 | 5.77 | N.A. | 6.62 | 5.76 | ||
| 20–29 | 42.38 | 39.60 | N.A. | 42.44 | 39.79 | ||
| 30–39 | 46.75 | 47.57 | N.A. | 46.77 | 48.41 | ||
| 40+ | 4.18 | 6.78 | N.A. | 4.16 | 6.04 | ||
| Unknown | 0.07 | 0.29 | N.A. | 0.00 | 0.00 | ||
| Maternal ageb (years): mean ± standard deviation | 29.79 ± 6.17 | 30.56 ± 6.46 | N.A. | <0.01 | 29.78 ± 6.16 | 30.44 ± 6.34 | <0.01 |
| Maternal education (%) | <0.01 | ||||||
| College or higher | N.A. | N.A. | N.A. | 57.26 | 52.71 | ||
| High school or lower | N.A. | N.A. | N.A. | 40.82 | 43.93 | ||
| Unknown | N.A. | N.A. | N.A. | 1.92 | 3.36 | ||
| Race/ethnicityb (%) | <0.01 | <0.01 | |||||
| Asian | 10.49 | 9.61 | N.A. | 13.65 | 14.85 | ||
| Black | 8.47 | 6.68 | N.A. | 8.96 | 6.20 | ||
| Hispanic | 33.01 | 42.74 | N.A. | 36.97 | 39.42 | ||
| Non-Hispanic White | 39.62 | 30.56 | N.A. | 37.62 | 35.72 | ||
| Other | 4.52 | 5.00 | N.A. | 1.91 | 1.98 | ||
| Unknown | 3.88 | 5.41 | N.A. | 0.89 | 1.84 | ||
| Insuranceb (%) | <0.01 | <0.01 | |||||
| Private | 65.95 | 57.81 | N.A. | 66.77 | 66.91 | ||
| Public | 29.97 | 35.66 | N.A. | 32.69 | 32.25 | ||
| Other | 0.00 | 0.00 | N.A. | 0.44 | 0.63 | ||
| Unknown | 4.07 | 6.54 | N.A. | 0.11 | 0.20 | ||
* p-value for the comparison between the matched Memorial Care and the unmatched Memorial Care data with valid matching variables
** p-value for the comparison between the matched birth certificate data and the unmatched birth certificate data (all had valid matching variables)
aAll records in the unmatched birth certificate data had valid matching variables
bBoth databases have reported values for these variables. In this table, we calculated the statistic summaries based on the values reported in each specific database