Obsessive-compulsive disorder (OCD) symptoms are remarkably diverse, as regards both clinical presentation and severity1. Studies are conflicting about whether any specific phenotype of OCD is easier to treat or likely to benefit from a particular treatment. Duration of untreated illness (DUI) represents a modifiable parameter, whose reduction may positively influence the outcome and long-term course of specific psychiatric disorders2. The aim of this study was to evaluate possible differences concerning severity, duration of illness (DI) and DUI among OCD subtypes in a sample of OCD patients.

114 OCD outpatients were recruited and assessed using the Y-BOCS. The main OCD phenotypes were identified through the YBOCS- Symptom Checklist. A one-way ANOVA test was performed to compare DUI, DI and Y-BOCS scores in the sample.

Subjects were categorized into 4 clinical phenotypes,: aggressive/checking (n=31), contamination/cleaning (n=37), simmetry/ordering (n=32) and multiple phenotypes (n=14). DUI, DI and YBOCS scores were found significantly higher in aggressive/checking subgroup, compared to other subgroups (One Way ANOVA: F=3.58 p<0.01; F=3.07 p<0.01; F=4.390 p<0.01). Furthermore, the mean DUI of the whole OCD sample, (87.35 ± 110.75 months) resulted approximately half of the mean DI (172.2 ± 132.36 months).

DUI and DI resulted significantly higher in the aggressive/checking subgroup, compared to the other subgroups. YBOCS scores resulted significantly higher in the aggressive/checking subgroup compared to the others, showing that longer DUI and DI may condition a worse clinical outcome in this subgroup. Of note, within the total sample half of the whole DI was spent untreated.