Table.
Controlling for individual potential confounders of immunisation
| Potential confounders | Proportion (%) of immunised infants
|
Mantel-Haenszel pooled odds ratio (95% confidence interval) | |
|---|---|---|---|
| SIDS infants | Control infants | ||
| Overall | 149/303 (49) | 822/1234 (67) | 0.48 (0.37 to 0.63)* |
| Age of infant (days)†: | |||
| <91 | 33/157 (21) | 184/546 (34) | |
| 91-120 | 36/46 (78) | 177/200 (89) | |
| >120 | 80/100 (80) | 461/488 (94) | 0.43 (0.29 to 0.59) |
| Socioeconomic group‡: | |||
| I and II | 18/43 (42) | 280/428 (65) | |
| III (non-manual) | 44/78 (56) | 266/387 (69) | |
| III (manual) and IV | 60/114 (53) | 215/328 (66) | |
| V and unemployed | 27/67 (40) | 58/87 (67) | 0.50 (0.38 to 0.65) |
| Moved house in past year: | |||
| No | 82/159 (52) | 651/977 (67) | |
| Once | 47/94 (50) | 139/204 (68) | |
| Twice or more | 20/49 (41) | 30/50 (60) | 0.51 (0.38 to 0.66) |
| Maternal age (years): | |||
| >29 | 29/62 (47) | 271/410 (66) | |
| 25-29 | 30/75 (40) | 305/444 (69) | |
| <25 | 90/166 (54) | 246/380 (65) | 0.49 (0.37 to 0.63) |
| No of children in family: | |||
| 1 child | 47/84 (56) | 354/529 (67) | |
| 2 or 3 children | 80/169 (47) | 414/610 (68) | |
| >3 children | 22/50 (44) | 54/95 (57) | 0.50 (0.39 to 0.66) |
| Birth weight (g): | |||
| ⩾2500 | 116/236 (49) | 776/1163 (67) | |
| <2500 | 33/67 (49) | 39/64 (61) | 0.50 (0.38 to 0.66) |
| Gestational age (weeks): | |||
| >38 | 49/104 (47) | 453/696 (65) | |
| 37-38 | 70/140 (50) | 319/461 (69) | |
| <37 | 30/58 (52) | 41/66 (62) | 0.48 (0.37 to 0.63) |
| Admitted to special care baby unit: | |||
| No | 112/229 (49) | 751/1139 (66) | |
| Yes | 37/74 (50) | 65/87 (75) | 0.47 (0.35 to 0.61) |
| Admitted to hospital: | |||
| No | 97/212 (46) | 664/1027 (65) | |
| Yes | 51/88 (58) | 157/206 (76) | 0.45 (0.35 to 0.59) |
| Five minute Apgar score: | |||
| ⩾8 | 139/277 (50) | 772/1170 (66) | |
| <8 | 6/15 (40) | 20/25 (80) | 0.50 (0.38 to 0.65) |
| Apparent life threatening event§: | |||
| No episodes | 128/262 (49) | 792/1196 (66) | |
| One episode or more | 19/34 (56) | 29/37 (78) | 0.48 (0.36 to 0.62) |
SIDS infants=infants whose deaths were attributed to sudden infant death syndrome.
*
Unmatched odds ratio.
†
Cut-offs were chosen on the basis of the infants who died within three months (some of who died after vaccination at age 2 months), those who died aged 3 to 4 months (after the second vaccination), and those who died after age 4 months and the final vaccination.
‡
Based on highest occupational status of parent(s) and previous occupation if currently unemployed.
§
Any episode of lifelessness described by the parents.