Sixty-four UHR and 26 NPC youth completed the SCID interview. Forty-nine (77%) of the UHR and 21 (81%) of the NPC youth completed the Padua Inventory. While 4% of PI non-completers discontinued the study before finishing their questionnaires, 18% of non-completers failed to complete the Padua despite completion of other study procedures. However, completers and non-completers of the Padua Inventory did not differ on any demographic variables. The rates of Padua non-completion did not differ significantly between the NPC, OCD+ and OCD- groups [χ2(2, n=90)=0.70, p=0.71]. Four OCD+ adolescents in the UHR sample did not complete the PI during their participation in the study. However, these UHR individuals did not differ significantly from the remaining UHR participants who did complete the PI on any demographic, clinical, or psychosocial variables of interest (p>0.19 for all comparisons).
Across the whole sample, the normalized PI Total score did not significantly differ based on parental education [Completed college vs. Less than college, F(1,67)=0.58, p=0.45] or gender [39% female; F(1, 68)=0.14, p=0.71]. However, the normalized PI Total score was negatively associated with age [r=-0.23, p=0.058]; thus, age was entered as a covariate in subsequent analyses. Within the UHR group, the rate of OCD diagnosis did not differ as a function of age [F(1, 62)=2.30, p=0.14], parental education [χ2(1, n=61)=2.65, p=0.10], or gender [χ2(1, n=64)=0.35, p=0.56].
Twenty percent (n=13) of the UHR participants were coded as OCD+, with 14% (n=9) receiving a DSM-IV diagnosis of OCD and 6% (n=4) considered subthreshold OCD. Notably, there was a trend toward difference in rates of conversion to psychosis, as none of the OCD+ youth converted to psychosis over the 11 month, on average, follow-up period [χ2(1, n=64)=3.39, p=0.06; Conversion rate=0% in OCD+ group vs. 22% in OCD- group]. However, OCD+ youth did not differ significantly from OCD- youth on any measures of clinical symptom severity, psychosocial functioning, treatment with atypical antipsychotic or SSRI medication, or rates of hospitalization (p>0.13 for all comparisons).
As shown in , ANCOVA revealed significant differences between the three participant groups on the normalized PI Total score [F(2, 66)=8.30, p=0.001] after controlling for the effects of age. While PI Total Score did not significantly differ between the OCD+ (n=9) and OCD-(n=40) groups [F(1,46)=0.15, p=0.71], the PI Total score for each UHR group differed significantly from NPC youth [NPC (n=21) vs. OCD+, F(1,27)=15.10, p=0.001; NPC vs. OCD-, F(1,58)=15.71, p<0.001], suggesting that UHR youth, as a whole, reported more OCS than their demographically matched peers.
Participants’ mean (± SE mean) scores on the Padua Inventory according to diagnostic group. [* p<0.01, ** p<0.001]
As the OCD+ and OCD- groups did not differ significantly on the normalized PI Total or Index scores (p>0.13 for all comparisons), they were combined into one UHR group for analysis of the four Index scores. Post-hoc examination of the normalized PI Index scores revealed that UHR participants, after controlling for age, reported significantly more OC symptoms related to Mental Control [UHR mean(SD)=15.04(13.86) vs NPC mean(SD)=2.14(2.39); F(1,67)=21.86, p<0.001], Checking [UHR mean(SD)=4.82(5.91) vs NPC mean(SD)=0.90(1.30); F(1, 67)=10.98, p=0.001] and Motor Control [UHR mean(SD)=2.61(3.84) vs NPC mean (SD)=0.29(0.64); F(1, 67)=10.78, p=0.002] when compared to NPC participants. However, no significant difference between UHR and NPC youth was noted on the Contamination Factor [UHR mean(SD)=8.24(8.04) vs. NPC mean(SD)=4.57(5.24); F(1, 67)=2.63, p=0.11].
After controlling for the effects of age, normalized PI Total score showed a significant association with severity of SIPS Positive Symptoms [r=0.40, p=0.005] and a trend association with SIPS Negative Symptoms [r=0.26 p=0.08] within the UHR sample. Furthermore, PI Total Score was significantly associated with increased self-reported symptoms of depression on the BDI [r=0.63, p<0.001] and a trend association with clinician-rated level of suicidality [BPRS Suicidality, r=0.32, p=0.04] for UHR individuals. Within the UHR sample, PI Total Score was not associated with clinician-rated level of depression [BPRS Depression, r=0.18, p=0.25] or current psychosocial functioning [GFS, r=-0. 04, p=0.80; GFR, r=-0.02, p=0.92] after controlling for age. UHR participants’ PI Total Score also did not differ significantly based upon history of hospitalization [F(1,47)=0.21, p=0.65], conversion to psychosis [F(1,47)=0.02, p=0.88], use of atypical antipsychotic treatment [AA Current F(1,47)= 0.20, p=0.66; AA Past F(1,47)=0.76, p=0.39], or use of SSRI medication [SSRI Current F(1,47)= 0.59, p=0.45; SSRI Past F(1,47)=0.30, p=0.58].