Table 1. Demographic and clinical characteristics of schizophrenia subjects and unaffected siblings.
| Schizophrenia subjects (N = 293) | Unaffected siblings (N = 382a) | |||||
| n | % | n | % | P valueb | Odds Ratio (95% CI)c | |
| Gender (male) | 222 | 76 | 173 | 45 | <0.0001 | 3.9 (2.8, 5.5) |
| Race (white) | 216 | 74 | 305 | 80 | ||
| Smokerd | 126 | 44 | 62 | 16 | <0.0001 | 4.0 (2.7, 5.7) |
| Multiplex statuse | 18 | 6 | 28 | 7 | ||
| Mean | SD (Min, Max) | Mean | SD (Min, Max) | P valueb | Difference (95% CI)c | |
| Age (years) | 33.7 | 10.5 (18, 62) | 35.0 | 11.1 (18, 66) | 0.21 | |
| Education (years)f | 13.6 | 2.1 (8, 20) | 15.4 | 2.4 (7, 25) | <0.0001 | −1.7 (−2.0, −1.4) |
| Parental education (years)g | 15.9 | 3.4 (0, 25) | 15.8 | 3.6 (0, 25) | ||
| WRAT-3h | 102.5 | 10.9 (69, 122) | 106.5 | 9.5 (64, 125) | <0.0001 | −4.0 (−5.3, −2.7) |
| Age at onset of symptoms (years)i | 20.9 | 5.5 (6, 51) | ||||
| SANSj | 9.5 | 6.0 (0, 25) | ||||
| SAPSk | 6.2 | 4.1 (0, 20) | ||||
| Paternal age at birth (years) | 30.7 | 6.3 (18, 63) | 30.7 | 6.3 (16, 66) | 0.36 | |
Abbreviations: CI, confidence interval; SANS, Schedule for the Assessment of Negative Symptoms; SAPS, Schedule for the Assessment of Positive Symptoms; SD, standard deviation; WRAT-3, Wide Range Achievement Test, 3rd edition.
Unaffected siblings represent 279 families, of which 17 (6%) were multiplex.
Between-group P values are based on generalized linear mixed-effects models for categorical variables and linear mixed-effects models for continuous variables; P values were not computed for race, multiplex status, parental education, or age at onset of symptoms.
For continuous variables, differences between groups (probands – unaffected siblings) and 95% CIs for differences are based on linear mixed-effects models; for categorical variables, odds ratios and 95% CIs for odds ratios are based on generalized linear mixed-effects models. CIs are shown only for variables where the P value for the between-group test is <0.05.
4 missing values for schizophrenia subjects; 2 missing values for unaffected siblings.
Multiplex families were those for which at least one parent or sibling of the proband had a history of schizophrenia or schizoaffective disorder.
2 missing values for schizophrenia subjects; 2 missing values for unaffected siblings.
6 missing values for schizophrenia subjects; 3 missing values for unaffected siblings.
10 missing values for schizophrenia subjects; 12 missing values for unaffected siblings.
5 missing values for schizophrenia subjects.
7 missing values for schizophrenia subjects; 73 missing values for unaffected siblings.
7 missing values for schizophrenia subjects; 74 missing values for unaffected siblings.