Cyclooxygenase (COX) enzymes oxidize arachidonic acid to prostaglandins, which modulate normal neuronal function and inflammatory responses in the central nervous system. COX-2, which is constitutively expressed by glutamatergic neurons in the cortex, hippocampus, and amygdala, plays an important physiological role in synaptic plasticity and long-term potentiation. Pre-clinical studies point to a potential role for non-steroidal anti-inflammatory drugs (NSAIDs), which inhibit COX enzymes, in modulation of mood and anxiety symptoms. Recent meta-analyses also suggest a role for adjunctive COX inhibitors in the treatment of depression and first-episode schizophrenia. While consensus guidelines on the use of anti-inflammatory therapy in children with acute-onset subtypes of childhood-onset obsessive compulsive disorder (OCD) suggest NSAIDs as a first-line option for patients with mild impairment, there is limited empirical evidence to support their use in this population. Two small randomized-controlled trials in adults with OCD demonstrated improved symptom severity with celecoxib - a selective COX-2 inhibitor - raising the possibility that COX inhibition may be effective in a general OCD population.~The primary objective of this study is to compare the effects of celecoxib and placebo as adjuncts to treatment-as-usual on reduction in symptom severity, as determined by Children's Yale-Brown Obsessive Compulsive Scale (CY-BOCS) after 12 weeks in children and youth with moderate-to-severe OCD.~This is a randomized, controlled, single-centre superiority trial with two parallel groups (celecoxib 50 mg [≤25 kg] or 100 mg [>25 kg] twice daily and placebo). Participants will be recruited from the BC Children's Hospital (BCCH) Provincial OCD Program and based on self-referral from community practices. Randomization will be performed as block randomization with a 1:1 allocation and stratified based on pre-treatment symptom severity. The investigator, outcomes assessor, clinician, and patient will be blinded to the intervention groups. Labs at baseline and 12 weeks will include complete blood count (CBC) with differential, creatinine, electrolytes, liver enzymes, and CRP. Participants will be assessed for OCD severity and adverse events at weeks 6 and 12. Analysis will be carried out according to intention-to-treat principles. Power calculations using estimates based on previous studies suggest a target recruitment of 80 participants. Participants will be offered a 12-week open-label celecoxib extension following the blinded phase for further assessment of tolerability.~The primary outcome is OCD severity (as measured by total CY-BOCS score) after 12 weeks in the celecoxib compared to placebo arm, adjusted for baseline. Secondary outcomes include CY-BOCS score after 6 weeks adjusted for baseline OCD severity, difference in the proportion of participants achieving a clinically meaningful response or remission; mean clinical global impression of severity and improvement after 6 and 12 weeks; and difference between celecoxib and placebo arms in the proportion of participants reporting adverse events that are possibly, probably, or definitely related to the study intervention.~NSAIDs are common in clinical practice and referenced in both adult and pediatric treatment guidelines for OCD, but no controlled studies have evaluated the effects of COX inhibitors in childhood-onset OCD. This study will be the first to assess the efficacy and safety of adjunctive celecoxib in this population and will inform clinical management of children and youth with OCD.
This is a randomized, controlled, single-centre phase II superiority trial to determine the efficacy of 12 weeks of celecoxib (50 mg or 100 mg orally twice daily, dosed based on weight) compared to placebo as an adjunct to treatment-as-usual in children and youth with moderate-to-severe obsessive-compulsive disorder.