Table 5.
Interaction of prespecified risk factors with effect on neonatal mortality in newborn babies weighing <2000 g assigned to receive BCG Danish and OPV within 48 hours of admission (intervention) or delayed at least to discharge (control)
| Mortality rate (deaths/total person years); No | Hazard ratio (95% CI)* | P for interaction with BCG-OPV* | ||
|---|---|---|---|---|
| Early BCG-OPV | Control | |||
| Birth weight (g) | ||||
| <1000 | 9.67 (60/6.2); 133 | 12.7 (67/5.3); 129 | 0.75 (0.53 to 1.08) | 0.81† |
| 1000-1499 | 1.99 (130/65); 996 | 2.31 (148/64); 994 | 0.86 (0.68 to 1.09) | |
| 1500-1999 | 0.43 (48/113); 1585 | 0.52 (58/112); 1583 | 0.82 (0.56 to 1.21) | |
| Gestational weeks‡ | ||||
| <31.8 | 3.55 (148/42); 689 | 3.82 (159/42); 703 | 0.89 (0.71 to 1.12) | 0.82† |
| 31.8-33.6 | 0.69 (34/49); 705 | 1.24 (56/45); 662 | 0.56 (0.37 to 0.87) | |
| 33.7-35.4 | 0.56 (26/47); 664 | 0.56 (27/49); 683 | 0.92 (0.54 to 1.56) | |
| >35.4 | 0.65 (30/46); 656 | 0.67 (31/46); 658 | 0.95 (0.58 to 1.57) | |
| Maturity (weeks) | ||||
| Premature (<37) | 1.43 (228/160); 2374 | 1.62 (254/157); 2349 | 0.84 (0.70 to 1.01) | 0.47 |
| Term (≥37) | 0.41 (10/24); 340 | 0.76 (19/25); 357 | 0.63 (0.29 to 1.36) | |
| Sex | ||||
| Male | 1.57 (146/93); 1389 | 1.69 (155/92); 1382 | 0.88 (0.71 to 1.11) | 0.36 |
| Female | 1.01 (92/91); 1325 | 1.32 (118/90); 1324 | 0.75 (0.56 to 0.99) | |
| Birth location | ||||
| Study hospital | 1.22 (207/170); 2460 | 1.48 (246/167); 2454 | 0.81 (0.67 to 0.97) | 0.45 |
| Elsewhere | 2.12 (31/15); 254 | 1.81 (27/15); 252 | 0.99 (0.60 to 1.64) | |
| Maternal BCG scar | ||||
| Present | 1.22 (133/109); 1601 | 1.40 (157/112); 1658 | 0.78 (0.62 to 0.99) | 0.47 |
| Absent | 1.40 (105/75); 1110 | 1.68 (116/69); 1047 | 0.89 (0.69 to 1.15) | |
| Mode of delivery | ||||
| Caesarean section | 1.23 (100/81); 1191 | 1.24 (104/84); 1230 | 0.92 (0.70 to 1.21) | 0.31 |
| Vaginal delivery | 1.34 (138/103); 1523 | 1.73 (169/98); 1476 | 0.77 (0.61 to 0.96) | |
| Season | ||||
| Wet: Jul to Dec | 1.33 (128/96); 1431 | 1.52 (145/95); 1425 | 0.82 (0.64 to 1.05) | 0.97 |
| Dry: Jan to Jun | 1.25 (110/88); 1283 | 1.49 (128/86); 1281 | 0.83 (0.65 to 1.06) | |
CI=confidence interval; OPV=oral polio vaccine.
*
Cox regression stratified by neonatal intensive care unit and adjusted for age, birth weight, gestational age, and sex.
†
Interaction of continuous variables, weight, and (10/gestational−age)2, with the effect of BCG-OPV on mortality.
‡
Four groups with approximately equal numbers in each group.