Deborah Layton, Sarah Clarke, Ian Ratcliffe, Saad AW Shakir, Tony Hale

Background

Background:The aim of OASIS (ENCePP Study reg.5412) was to extend the post-authorisation safety knowledge of quetiapine XL, with a focus on short-term (12-week (w)) safety and high dose (>600mg/day) use, as prescribed by psychiatrists in patients (pts) with Schizophrenia (Schiz) or Bipolar Disorder (BD), vs quetiapine IR. Study objectives incl. quantifying event incidence and pattern.

Objectives

To compare common event rates between users defined by dose and formulation.

Methods

An observational cohort design. Questionnaires completed by specialists collected data on pt characteristics, exposure and events Dec2009-Dec2012. Exposure (pt-w) was calculated for: total cohort and stratified by formulation. Stratum specific exposure was calculated for three 4-w periods for total cohort, formulation and high dose use (where >600mg/day for >50% of each 4-w period). Crude event Incidence Densities (ID) per 1000 pt-w and ID differences (IDD+95%CI) were calculated within/between groups; IDD 95%CI excluding the null (0) were signals of events associated with starting treatment and/or high dose.

Results

Cohort = 845: Schiz: 338(40%), BD: 442(52%), Other: 65 (8%); 471 (59%) female; median age 39 (IQR 29,49). High dose use was reported for 28/631 (4%) in XL group and 3/214 (1%) IR group. The most frequently reported events (not associated with indication) were: sedation:ID 24, somnolence:ID 20, akasthesia: ID 3, and parkinsonism: ID 2. In the XL group, the IDDs for these 4 events were non-significantly lower for high vs standard dose for total study period and weeks 1-4. Within XL high dose group, sedation and somnolence were associated with starting treatment (IDD w 1-4 – w 5-8 : 25 (7, 42) and 14 (14, 15) respectively); this pattern was also observed within XL and IR standard dose groups. Low counts in high dose group and IR cohort precluded reliable comparisons.

Conclusion

This study found that sedation and somnolence were common events associated with starting treatment, but not with high dose. Although the frequency of high dose use was low, OASIS provides important information on the safety and utilisation of quetiapine XL.