Table IV.
Prevalence and PRs for spina bifida cases by lesion level and fortification period
Lesion level fortification period | No. of cases | No. of live births | Birth prevalence per 10 000 (95% CI) | PR (95% CI) | P value |
---|---|---|---|---|---|
All spina bifida cases* | |||||
Prefortification (1992-1996) | 573 | 1 407 707 | 4.07 (3.74-4.42) | Referent | Referent |
Postfortification, overall (1999-2016) | 2020 | 6 408 355 | 3.15 (3.02-3.29) | 0.77 (0.71-0.85) | <.0001 |
Early postfortification period (1999-2004) | 669 | 2 136 303 | 3.13 (2.90-3.38) | 0.77 (0.69-0.86) | <.0001 |
Mid postfortification period (2005-2010) | 787 | 2 331 761 | 3.38 (3.14-3.62) | 0.83 (0.74-0.92) | .0006 |
Recent postfortification period (2011-2016) | 564 | 1 940 291 | 2.91 (2.67-3.16) | 0.71 (0.64-0.80) | <.0001 |
Upper lesion level cases | |||||
Prefortification (1992-1996) | 141 | 1 407 707 | 1.00 (0.84-1.18) | Referent | Referent |
Postfortification, overall (1999-2016) | 177 | 6 408 355 | 0.28 (0.24-0.32) | 0.28 (0.22-0.34) | <.0001 |
Early postfortification period (1999-2004) | 75 | 2 136 303 | 0.35 (0.28-0.44) | 0.35 (0.26-0.46) | <.0001 |
Mid postfortification period (2005-2010) | 61 | 2 331 761 | 0.26 (0.20-0.34) | 0.26 (0.19-0.35) | <.0001 |
Recent postfortification period (2011-2016) | 41 | 1 940 291 | 0.21 (0.15-0.29) | 0.21 (0.15-0.30) | <.0001 |
Lower lesion level cases | |||||
Prefortification (1992-1996) | 400 | 1 407 707 | 2.84 (2.57-3.13) | Referent | Referent |
Postfortification, overall (1999-2016) | 1709 | 6 408 355 | 2.67 (2.54-2.80) | 0.94 (0.84-1.05) | .25 |
Early postfortification period (1999-2004) | 564 | 2 136 303 | 2.64 (2.43-2.87) | 0.93 (0.82-1.06) | .26 |
Mid postfortification period (2005-2010) | 660 | 2 331 761 | 2.83 (2.62-3.05) | 1.00 (0.88-1.13) | .95 |
Recent postfortification period (2011-2016) | 485 | 1 940 291 | 2.50 (2.28-2.73) | 0.88 (0.77-1.00) | .06 |
P values are for pairwise testing of the PR against the referent group for each period stratification.
All cases include unknown lesion level.