1 Department of Psychology, Memorial University of Newfoundland, 232 Elizabeth Ave., St. John's, NL, A1B 3X9, Canada. Electronic address: efawcett@mun.ca.
2 Department of Psychology, Memorial University of Newfoundland, 232 Elizabeth Ave., St. John's, NL, A1B 3X9, Canada.
3 Concordia University, 1455 De Maisonneuve Blvd. W, Montreal, QC, H3G 1M8, Canada.

Obsessive-compulsive disorder (OCD) is a heterogeneous condition often characterized in relation to major symptom dimensions, including contamination, symmetry/exactness, religious, aggressive, sexual, hoarding/saving, somatic, and miscellaneous. Aggressive obsessions, defined as intrusive thoughts of (unintentionally or intentionally) harming oneself or others, are experienced as distressing, commonly misdiagnosed by healthcare providers, and highly stigmatized. The aims of the current study were to: (a) provide an aggregate estimate of the worldwide prevalence of aggressive obsessions among adults (18+ years) with clinician-diagnosed OCD; and (b) quantify sources of heterogeneity amongst prevalence estimates using moderator analyses. A systematic review was conducted using PubMed, PsycINFO, and CINAHL databases. Of the 7794 studies screened, 110 were coded for analysis. Lifetime and current (e.g., past-week) prevalence rates were estimated to be 70.3 %, CI_{95 %} [61.6, 77.7], and 52.6 %, CI_{95 %} [46.3, 59.0], respectively, and reflected substantial heterogeneity. For 28.0 % of individuals, aggressive obsessions were categorized as their primary and most distressing symptom. Moderator analyses revealed higher current prevalence of aggressive obsessions across samples with a greater mean age, longer mean illness duration, lower mean age of OCD onset, and greater comorbid social anxiety disorder prevalence, while significantly fewer aggressive obsessions were reported in samples from the Asia Pacific region, and with higher percentages of married individuals. Finally, risk ratio analyses revealed that individuals with: a) early vs. late OCD onset; and b) suicidal ideation vs. not, were 1.17 times, CI_{95 %} [1.07, 1.27], and 1.98 times, CI_{95 %}[1.47, 2.66], more likely to report aggressive obsessions, respectively. Results support the need for early identification and increased monitoring among individuals experiencing aggressive obsessions.