Table 2.
Estimates of alcohol- and narcotics-attributable hospitalization or death (ages 30–55) between families, according to birth order. Results from Cox regression analyses.
| Alcohol |
Narcotics |
|||||||
|---|---|---|---|---|---|---|---|---|
| Model 1 |
Model 2 a |
Model 1 |
Model 2 a |
|||||
| HR | 95% CI | HR | 95% CI | HR | 95% CI | HR | 95% CI | |
| Birth order | ||||||||
| Second | 1.00 | 0.94–1.07 | 0.96 | 0.87–1.06 | 1.26*** | 1.13–1.39 | 1.13 | 0.96–1.32 |
| Third | 1.10* | 1.01–1.19 | 0.92 | 0.78–1.09 | 1.46*** | 1.30–1.65 | 1.15 | 0.89–1.49 |
| Fourth | 1.40*** | 1.25–1.56 | 1.04 | 0.82–1.31 | 1.67*** | 1.41–1.98 | 1.24 | 0.86–1.79 |
| Fifth | 1.63*** | 1.35–1.97 | 1.08 | 0.78–1.50 | 1.61** | 1.17–2.21 | 1.18 | 0.70–2.01 |
| N | 147,952 | 147,952 | ||||||
| Events (N) | 5109 | 2110 | ||||||
Notes: The sample is restricted to families of two to five children in which all children were born 1943–1960. Reference category is the first-born child. All models are stratified by sex.
HR=Hazard Ratio; CI=Confidence interval; statistical significance: *p < 0.05; **p < 0.01; ***p < 0.001.
a
Includes dummy variables for the child's year of birth, mother's year of birth, mother's age at first birth, and sibling group size; continuous measure of birth density; and multiplicative interaction term between sibling group size and birth density.