Background
Methods
Results
First stratum: Normal birth weight | |||||
---|---|---|---|---|---|
Underweight | Normal | All | |||
N
|
Prev.
|
N
|
N
| Exp. prev. = 19.2% | |
Ever in hospital
| 8 | 4.7% | 163 | 171 | PR = 2.40 |
Never
| 14 | 1.9% | 704 | 718 | M-H weight = 2.69 |
All
| 22 | 2.5% | 867 | 889 | |
Second stratum: Low birth weight
| |||||
Underweight
|
Normal
|
All
| |||
N
|
Prev.
|
N
|
N
| Exp. prev. = 31.1% | |
Ever in hospital
| 16 | 13.4% | 103 | 119 | PR = 2.54 |
Never
| 14 | 5.3% | 250 | 264 | M-H weight = 4.35 |
All
| 30 | 7.8% | 353 | 383 | |
Combined strata: Normal and low birth weight
| |||||
Underweight
|
Normal
|
All
| Exp. prev. = 22.8% | ||
N
|
Prev.
|
N
|
N
| PR (crude) = 2.90 | |
Ever in hospital
| 24 | 8.3% | 266 | 290 | PR (M-H) = 2.48 |
Never
| 28 | 2.9% | 954 | 982 | Confounding = -14.4% |
All
| 52 | 4.1% | 1220 | 1272 | P-value(het)*= 0.9 |
First stratum: Normal birth weight | |||||
---|---|---|---|---|---|
Underweight | Normal | All | |||
N
|
Prev.
|
N
|
N
| Exp. prev. = 19.2% | |
Ever in hospital
| 8 | 4.7% | 163 | 171 | PR = 2.40 |
Never
| 14 | 1.9% | 704 | 718 | M-H weight = 2.69 |
All
| 22 | 2.5% | 867 | 889 | |
Second stratum: Low birth weight
| |||||
Underweight
|
Normal
|
All
| |||
N
|
Prev.
|
N
|
N
| Exp. prev. = 31.1% | |
Ever in hospital
| 22 | 18.5% | 97 | 119 | PR = 2.71 |
Never
| 18 | 6.8% | 246 | 264 | M-H weight = 5.59 |
All
| 40 | 10.4% | 343 | 383 | |
Combined strata: Normal and low birth weight
| |||||
Underweight
|
Normal
|
All
| Exp. prev. = 22.8% | ||
N
|
Prev.
|
N
|
N
| PR (crude) = 3.17 | |
Ever in hospital
| 30 | 10.3% | 260 | 290 | PR (M-H) = 2.61 |
Never
| 32 | 3.3% | 950 | 982 | Confounding = -17.8% |
All
| 62 | 4.9% | 1210 | 1272 | P-value(het)*= 0.8 |
First stratum: High social class | |||||
---|---|---|---|---|---|
Asthma | No | All | |||
N
|
Prev.
|
N
|
N
| Exp. prev. = 26.6% | |
Mother smokes
| 37 | 25.7% | 107 | 144 | PR = 1.19 |
No
| 86 | 21.6% | 312 | 398 | M-H weight = 22.85 |
All
| 123 | 22.7% | 419 | 542 | |
Second stratum: Low social class
| |||||
Asthma
|
No
|
All
| |||
N
|
Prev.
|
N
|
N
| Exp. prev. = 43.3% | |
Mother smokes
| 122 | 42.8% | 163 | 285 | PR = 1.24 |
No
| 129 | 34.6% | 244 | 373 | M-H weight = 55.87 |
All
| 251 | 38.1% | 407 | 658 | |
Combined strata: High and low social class
| |||||
Asthma
|
No
|
All
| Exp. prev. = 35.8% | ||
N
|
Prev.
|
N
|
N
| PR (crude) = 1.33 | |
Mother smokes
| 159 | 37.1% | 270 | 429 | PR (M-H) = 1.22 |
No
| 215 | 27.9% | 556 | 771 | Confounding = -7.9% |
All
| 374 | 31.2% | 826 | 1200 | P-value(het)*= 0.8 |
First stratum: High social class | |||||
---|---|---|---|---|---|
Asthma | No | All | |||
N
|
Prev.
|
N
|
N
| Exp. prev. = 26.6% | |
Mother smokes
| 21 | 14.6% | 123 | 144 | PR = 1.21 |
No
| 48 | 12.1% | 350 | 398 | M-H weight = 12.75 |
All
| 69 | 12.7% | 473 | 542 | |
Second stratum: Low social class
| |||||
Asthma
|
No
|
All
| |||
N
|
Prev.
|
N
|
N
| Exp. prev. = 43.3% | |
Mother smokes
| 194 | 68.1% | 91 | 285 | PR = 1.70 |
No
| 149 | 39.9% | 224 | 373 | M-H weight = 64.54 |
All
| 343 | 52.1% | 315 | 658 | |
Combined strata: High and low social class
| |||||
Asthma
|
No
|
All
| Exp. prev. = 35.8% | ||
N
|
Prev.
|
N
|
N
| PR (crude) = 1.96 | |
Mother smokes
| 215 | 50.1% | 214 | 429 | PR (M-H) = 1.62 |
No
| 197 | 25.6% | 574 | 771 | Confounding = -17.3% |
All
| 412 | 34.3% | 788 | 1200 | P-value(het)*= 0.2 |
First stratum: High social class | |||||
---|---|---|---|---|---|
Mother employed | No | All | |||
N
|
Prev.
|
N
|
N
| Prev. exp. = 15.3% | |
Father Present
| 66 | 79.5% | 17 | 83 | PR = 1.46 |
No
| 250 | 54.5% | 209 | 459 | M-H weight = 38.28 |
All
| 316 | 58.3% | 226 | 542 | |
Second stratum: Low social class
| |||||
Mother employed
|
No
|
All
| |||
N
|
Prev.
|
N
|
N
| Prev. exp. = 24.0% | |
Father present
| 112 | 70.9% | 46 | 158 | PR = 1.88 |
No
| 189 | 37.8% | 311 | 500 | M-H weight = 45.38 |
All
| 301 | 45.7% | 357 | 658 | |
Combined strata: High and low social class
| |||||
Mother employed
|
No
|
All
| Prev. exp. = 20.1% | ||
N
|
Prev.
|
N
|
N
| PR (crude) = 1.61 | |
Father present
| 178 | 73.9% | 63 | 241 | PR (M-H) = 1.69 |
No
| 439 | 45.8% | 520 | 959 | Confounding = 4.4% |
All
| 617 | 51.4% | 583 | 1200 | P-value(het) *= 0.01 |
First stratum: High social class | |||||
---|---|---|---|---|---|
Mother employed | No | All | |||
N
|
Prev.
|
N
|
N
| Prev. exp. = 15.0% | |
Father Present
| 73 | 90.1% | 8 | 81 | PR = 1.80 |
No
| 230 | 50.0% | 230 | 460 | M-H weight = 34.44 |
All
| 303 | 56.0% | 238 | 541 | |
Second stratum: Low social class
| |||||
Mother employed
|
No
|
All
| |||
N
|
Prev.
|
N
|
N
| Prev. exp.= 80.0% | |
Father Present
| 295 | 56.0% | 232 | 527 | PR = 1.39 |
No
| 53 | 40.2% | 79 | 132 | M-H weight = 42.38 |
All
| 348 | 52.8% | 311 | 659 | |
Combined strata: High and low social class
| |||||
Mother employed
|
No
|
All
| Prev. exp.= 50.7% | ||
N
|
Prev.
|
N
|
N
| PR (crude) = 1.27 | |
Father Present
| 368 | 60.5% | 240 | 608 | PR (M-H) = 1.58 |
No
| 283 | 47.8% | 309 | 592 | Confounding = 24.6% |
All
| 651 | 54.3% | 549 | 1200 | P-value(het) *= 0.01 |
Discussion
Original data | Point estimate | 95% Confidence interval | ||||
---|---|---|---|---|---|---|
value | % diff. | lower | upper | width | % diff. | |
PR Mantel-Haenszel
|
2.48
| -- |
1.46
|
4.23
|
2.78
| -- |
PR Poisson/Cox (unadj) | 2.48 | -0.2% | 1.43 | 4.31 | 2.88 | 3.6% |
PR Poisson (χ2) | 2.48 | -0.2% | 1.44 | 4.26 | 2.82 | 1.5% |
PR Poisson (deviance) | 2.48 | -0.2% | 1.89 | 3.25 | 1.36 | -51.1% |
PR Poisson/Cox (robust) | 2.48 | -0.2% | 1.46 | 4.22 | 2.76 | -0.6% |
PR log-binomial | 2.48 | -0.1% | 1.46 | 4.22 | 2.77 | -0.4% |
OR logistic regression | 2.64 | 6.3% | 1.49 | 4.68 | 3.18 | 14.6% |
Modified data | Point estimate | 95% Confidence interval | ||||
value | % diff. | lower | upper | width | % diff. | |
PR Mantel-Haenszel
|
2.61
| -- |
1.61
|
4.23
|
2.61
| -- |
PR Poisson/Cox (unadj) | 2.60 | -0.4% | 1.57 | 4.30 | 2.73 | 4.6% |
PR Poisson (χ2) | 2.60 | -0.4% | 1.59 | 4.26 | 2.67 | 2.4% |
PR Poisson (deviance) | 2.60 | -0.4% | 2.01 | 3.36 | 1.35 | -48.3% |
PR Poisson/Cox (robust) | 2.60 | -0.4% | 1.61 | 4.19 | 2.58 | -1.2% |
PR log-binomial | 2.61 | -0.1% | 1.61 | 4.21 | 2.60 | -0.7% |
OR logistic regression | 2.85 | 9.3% | 1.68 | 4.84 | 3.15 | 20.7% |
Conclusions
Original data | Point estimate | 95% Confidence interval | ||||
---|---|---|---|---|---|---|
value | % diff. | lower | upper | width | % diff. | |
PR Mantel-Haenszel
|
1.22
| -- |
1.03
|
1.45
|
0.41
| -- |
PR Poisson/Cox (unadj) | 1.22 | 0.0% | 0.99 | 1.51 | 0.51 | 23.9% |
PR Poisson (χ2) | 1.22 | 0.0% | 1.03 | 1.45 | 0.42 | 2.7% |
PR Poisson (deviance) | 1.22 | 0.0% | 1.03 | 1.46 | 0.43 | 3.9% |
PR Poisson/Cox (robust) | 1.22 | 0.0% | 1.03 | 1.45 | 0.41 | -0.2% |
PR log-binomial | 1.23 | 0.1% | 1.04 | 1.45 | 0.41 | -0.4% |
OR logistic regression | 1.36 | 11.0% | 1.05 | 1.76 | 0.71 | 70.9% |
Modified data | Point estimate | 95% Confidence interval | ||||
value | % diff. | lower | upper | width | % diff. | |
PR Mantel-Haenszel
|
1.62
| -- |
1.41
|
1.87
|
0.47
| -- |
PR Poisson/Cox (unadj) | 1.62 | -0.4% | 1.33 | 1.96 | 0.63 | 36.0% |
PR Poisson (χ2) | 1.62 | -0.4% | 1.38 | 1.90 | 0.52 | 10.9% |
PR Poisson (deviance) | 1.62 | -0.4% | 1.39 | 1.88 | 0.49 | 4.3% |
PR Poisson/Cox (robust) | 1.62 | -0.4% | 1.40 | 1.86 | 0.46 | -2.0% |
PR log-binomial | 1.65 | 1.7% | 1.44 | 1.90 | 0.46 | -1.5% |
OR logistic regression | 2.49 | 53.5% | 1.90 | 3.27 | 1.37 | 193.1% |
Original data | Point estimate | 95% Confidence interval | ||||
---|---|---|---|---|---|---|
value | % diff. | lower | upper | width | % diff. | |
PR Mantel-Haenszel
|
1.69
| -- |
1.52
|
1.87
|
0.35
| -- |
PR Poisson/Cox (unadj) | 1.68 | -0.3% | 1.41 | 2.00 | 0.59 | 68.6% |
PR Poisson (χ2) | 1.68 | -0.3% | 1.49 | 1.90 | 0.41 | 17.2% |
PR Poisson (deviance) | 1.68 | -0.3% | 1.46 | 1.94 | 0.48 | 35.9% |
PR Poisson/Cox (robust) | 1.68 | -0.3% | 1.52 | 1.86 | 0.35 | -1.5% |
PR log-binomial | 1.62 | -4.0% | 1.47 | 1.78 | 0.32 | -10.4% |
OR logistic regression | 3.75 | 122.6% | 2.72 | 5.17 | 2.45 | 597.6% |
Modified data | Point estimate | 95% Confidence interval | ||||
value | % diff. | lower | upper | width | % diff. | |
PR Mantel-Haenszel
|
1.58
| -- |
1.39
|
1.79
|
0.40
| -- |
PR Poisson/Cox (unadj) | 1.61 | 2.0% | 1.31 | 1.97 | 0.66 | 63.2% |
PR Poisson (χ2) | 1.61 | 2.0% | 1.40 | 1.85 | 0.45 | 10.3% |
PR Poisson (deviance) | 1.61 | 2.0% | 1.37 | 1.89 | 0.53 | 31.0% |
PR Poisson/Cox (robust) | 1.61 | 2.0% | 1.42 | 1.83 | 0.41 | 2.1% |
PR log-binomial | 1.71 | 8.7% | 1.53 | 1.92 | 0.39 | -4.7% |
OR logistic regression | 2.97 | 88.1% | 2.14 | 4.11 | 1.96 | 385.9% |