Table 3

 Variables considered for entry into the logistic regression models and their corresponding independent significance levels for SIB and severe SIB

VariableSIBSevere SIB
*Indicates variables that were not entered into the overall logistic regression model, owing to lack of association with either SIB or severe SIB independently.
Gender*χ2 = 0.778; p = 0.780Fisher; p = 1.00
Age at interview (under or over 18)*χ2 = 3.73; p = 0.053Fisher; p = 0.205
Referral sourceχ2 = 17.2; p = 0.002Fisher; p = 0.571
Tic severity
    MotorZ = 5.45; p<0.0001Z = 2.14; p = 0.032
    PhonicZ = 4.93 p<0.0001Z = 2.63; p = 0.009
Environmental and genetic factors
    Prenatal problems*χ2 = 0.41; p = 0.82Fisher; p = 0.396
    Perinatal distress*χ2 = 1.43; p = 0.49Fisher; p = 0.75
    Family history of TS*χ2 = 0.28; p = 0.60Fisher; p = 0.695
    Bilineal family history of TS*χ2 = 0.64; p = 0.42Fisher; p = 0.282
    Family history of OCSχ2 = 14.07; p<0.0001Fisher; p = 0.75
Obsessive symptoms
    OCDFisher; p<0.0001Fisher; p = 0.008
    Number of obsessive symptomsZ = 5.28; p<0.0001Z = 2.1; p = 0.03
    Violent obsessionsχ2 = 33.85; p<0.0001Fisher; p = 0.028
    Violent/aggressive compulsive behavioursχ2 = 28.39; p<0.0001Fisher; p = 0.005
Attentional symptoms
    ADHDχ2 = 5.19; p = 0.023Fisher; p = 0.121
    ADHD, impulsive symptomsFisher; p = 0.089Fisher; p = 0.141
    ADHD, inattentive symptoms*χ2 = 3.71; p = 0.16Fisher; p = 0.163
    ADHD, hyperactive symptoms*Fisher; p = 0.033Fisher; p = 0.141
Other psychiatric comorbidities
    OCD+ADHDχ2 = 17.67; p<0.0001χ2 = 7.89; p = 0.005
    Ragesχ2 = 5.53; p = 0.019Fisher; p = 0.002
    Risk takingFisher; p = 0.02Fisher; p = 0.122
    Anxiety disorders*χ2 = 0.48; p = 0.49Fisher; p = 1.000
    Mood disorders*Fisher; p = 1.000Fisher; p = 0.301
    Conduct disorders*χ2 = 1.23; p = 0.27Fisher; p = 0.133
    Eating disorders*χ2 = 0.027; p = 0.87Fisher; p = 0.214