Table 4.
Clinical features in Discovery sample BPI subjects grouped by externalizing disorders (continuous parameters).
| Non-Externalizing Group vs. Externalizing Group
| |||||||
|---|---|---|---|---|---|---|---|
| Parameter | Non-Externalizing | Externalizing | t | df | P (two-sided)b | ||
|
| |||||||
| Mean | SD | Mean | SD | ||||
| Age | 44.01 (N=467) | 13.49 | 41.06 (N=782) | 11.52 | 3.954 | 862.231 | <0.001 |
| Years of school | 15.18 (N=452) | 2.81 | 14.06 (N=767) | 2.84 | 6.694 | 1217 | <0.001 |
| Age at onset of illness | 21.36 (N=447) | 9.92 | 17.38 (N=774) | 7.94 | 7.250 | 776.393 | <0.001 |
| Age at onset of depression | 21.93 (N=425) | 10.70 | 18.48 (N=746) | 9.46 | 5.533 | 796.274 | <0.001 |
| Age at onset of mania | 26.61 (N=452) | 11.52 | 22.83 (N=750) | 9.84 | 5.807 | 837.128 | <0.001 |
| Age of first drink | 16.72 (N=197) | 4.68 | 14.06 (N=422) | 4.88 | 6.392 | 617 | <0.001 |
| Age of first tobacco use | 16.03 (N=244) | 5.35 | 14.89 (N=579) | 5.23 | 2.855 | 821 | 0.004 |
| Number of suicide attempts | 2.62 (N=144) | 2.55 | 3.51 (N=380) | 4.99 | −2.680 | 478.609 | 0.008 |
| Age of first suicide attempt | 24.46 (N=74) | 10.32 | 21.26 (N=229) | 8.44 | 2.676 | 301 | 0.008 |
| Interepisode GASa | 75.30 (N=206) | 14.94 | 70.14 (N=270) | 14.64 | 3.771 | 474 | <0.001 |
| Non-Externalizing Group vs. Early-Onset Subgroup
| |||||||
|---|---|---|---|---|---|---|---|
| Parameter | Non-Externalizing | Early-Onset | t | df | P (two-sided)b | ||
|
| |||||||
| Mean | SD | Mean | SD | ||||
| Age | 44.01 (N=467) | 13.49 | 39.80 (N=325) | 11.00 | 4.825 | 770.462 | <0.001 |
| Years of school | 15.18 (N=452) | 2.81 | 13.45 (N=325) | 2.82 | 8.464 | 775 | <0.001 |
| Age at onset of illness | 21.36 (N=447) | 9.92 | 16.03 (N=322) | 7.55 | 8.460 | 764.467 | <0.001 |
| Age at onset of depression | 21.93 (N=425) | 10.70 | 16.93 (N=312) | 9.10 | 6.840 | 719.155 | <0.001 |
| Age at onset of mania | 26.61 (N=452) | 11.52 | 21.29 (N=309) | 9.46 | 6.962 | 733.888 | <0.001 |
| Age of first drink | 16.72 (N=197) | 4.68 | 12.98 (N=206) | 4.32 | 8.345 | 401 | <0.001 |
| Age of first tobacco use | 16.03 (N=244) | 5.35 | 14.02 (N=269) | 5.47 | 4.208 | 511 | <0.001 |
| Number of suicide attempts | 2.62 (N=144) | 2.55 | 3.64 (N=181) | 4.27 | −2.661 | 301.360 | 0.008 |
| Age of first suicide attempt | 24.46 (N=74) | 10.32 | 20.30 (N=115) | 8.54 | 3.012 | 187 | 0.003 |
| Interepisode GASa | 75.30 (N=206) | 14.94 | 69.29 (N=108) | 14.89 | 3.389 | 312 | 0.001 |
a
GAS, Global Assessment Scale.
b
P-values were determined after performing Levene’s Test for Equality of Variances to check equality of variances assumption.