Squares depict measured variables and circles represent latent variables. The standardized coefficients represent the size of the effects and the P-values in parentheses represent the significance of these effects as a result of the Wald test. An effect is deemed to be statistically significant if the P-value for the Wald test for each of the γ's, α's and β's is smaller than 0.05 (see text). The standardized coefficients are the proportion of 1.0 standard deviation (SD) of the predicted variable that can be explained by 1.0 SD change in the predicting variable. However, since GABHS infection is an event with a binary outcome for which analysis of SD is not appropriate, the GABHS coefficient was standardized only using the SD of the respective symptom severity measure. A solid line indicates a statistically significant positive relationship; a dashed line indicates a significant inverse relationship. The thickness of the line reflects its relative significance. An arrow indicates a predictive relationship, while a line without an arrow head indicates the relative contributions to the latent variable of psychosocial stress. The Stress Construct (SC) is the latent construct derived from the Yale Children's Global Stress Index (YCGSI), the Perceived Stress Scale–Parent (PSS-P) and the Daily Life Stress Scale (DLSS). The size of the coefficients associated the SC indicate the relative contributions of the PSS-P, DLSS, and YCGSI to the latent stress construct. A. Future tic severity. Future tic improvement was associated with advancing chronological age. The standardized coefficient of 0.33 means that following an increase of 2.7 years of age (1 SD of all measures of age in the patient population), we observed a reduction of 33% of 1.0 SD of all the YGTSS scores (.33 × 9.0 ≈ 3.0). In addition, newly diagnosed GABHS infections (defined by either the Definite or the Definite plus Possible criteria) were associated with future worsening of tic severity. Due to the binary nature of the GABHS infection, the standardized coefficient of 0.41 (for Definite infections) means that the new infection associated with a 3.7 point increase of the YGTSS scores compared to the YGTSS score obtained approximately one month later (41% × 9.0 ≈ 3.7). In addition, increases in past depressive symptoms (Children's Depression Rating Scale-Revised, CDRS-R_T−1) predict higher levels of current psychosocial stress, which in turn modestly, but significantly, predict increases in future tic severity (Yale Global Tic Severity Scale, YGTSS_T+1). Increases in current depressive symptoms (Children's Depression Rating Scale-Revised, CDRS-R_T) are also modestly, and independently, predictive of increases in future tic symptom severity (YGTSS_T+1). Prior tic symptom severity (YGTSS_T−1) does not affect current depressive symptom ratings; and past YGTSS scores also do not significantly affect current stress levels (data not shown). In the case of future tic severity, the DLSS has the strongest predictive. The inclusion of newly diagnosed GABHS infections greatly increased (by a factor of almost three) the effect size of psychosocial stress to predict future tic symptom severity, as the standardized coefficient increased from 0.13 to 0.37 (12). B. Future obsessive-compulsive (OC) symptom severity. Future OC symptom worsening was associated with antecedent increases in SC and with Possible newly acquired GABHS infections, but not Definite, newly acquired GABHS infections. Increases Children's Yale-Brown Obsessive Compulsive Scale (CY-BOCS) scores also predict future increases in depressive symptoms (CDRS-R_T+1). The degree of increase in OC symptom severity following Possible GABHS infections was less than that seen in predicting future tic severity. However, the inclusion of newly diagnosed GABHS infections greatly increased by a factor of more than three the power of psychosocial stress to predict future OC symptom severity as the standardized coefficient increased from 0.26 to 0.84 (12). C. Future Depressive Symptom Severity. Antecedent increased in depressive symptom severity and with either Definite or Possible GABHS infections predict higher levels of psychosocial stress. Current levels of psychosocial stress, in turn, predicts future depressive symptom severity.