‘Weak’ association
The final cohort consisted of 428,525 individuals (mean [SD] age, 36.8 [15.4] years, 52.7% female) at baseline, with observation taking place over a mean of 4.8 years [range, 1 day to 10.5 years]) or a total of over 2 million (2,062,241) person-years.
Of the cohort, 4.3% (n = 18,317) had at least two prescriptions for either olanzapine or quetiapine (although subsequently, 86.5% were censored for exceeding the average OE dose of 5 mg/day).
By the end of the study, 3.1% of the cohort had died during the observation time, and of these, 69.5% were from disease-specific causes, while close to one-fifth (19.5%) were from cardiometabolic-specific causes.
On the whole, treatment status (i.e., treated vs. untreated) was not significantly associated with cardiometabolic mortality (adjusted hazard ratio [HR], .86 [95% confidence interval, 0.64-1.15]; P = .307).
Compared to no treatment, treatment with olanzapine or quetiapine for less than 6 months was significantly associated with a reduced risk of cardiovascular mortality (adjusted HR, .56 [.37 – .87]; P = .010). On the other hand, treatment for 6-12 months was significantly associated with an almost twofold increased risk (adjusted HR, 1.89 [1.22-2.92]; P = .004). The increased risk continued beyond 12 months, although the difference no longer remained significant.
“In the subgroup analysis consisting of individuals who had ever been treated with olanzapine/quetiapine, starting at the date of their first prescription, the hazard for cardiometabolic mortality increased significantly by 45% (6%-99%; P = .019) for every year exposed to an average 5 mg/day,” the authors reported.
The authors concluded that the association between low-dose olanzapine/quetiapine treatment and cardiometabolic mortality was present, but “weak.”
The hazard for disease-specific mortality also significantly increased with each year exposed to an average of 5 mg/day of OE (HR, 1.24 [1.03-1.50]; P = .026).
Treatment status similarly was associated with all-cause mortality (HR, 1.16 [1.03-1.30]; P = .012), although the increased hazard for all-cause mortality with each year of exposure was not considered significant.
“The findings of this study are consistent with the hypothesis that continuous low-dose treatment with these drugs is associated with increased cardiometabolic mortality, but ,” Dr. Berge said.
Seek alternatives
Commenting on the study for this news organization, Roger S. McIntyre, MD, professor of psychiatry and pharmacology, University of Toronto, and head of the Mood Disorders Psychopharmacology Unit, called it a “timely paper” and “an important concept [because] low-doses of these antipsychotics are frequently prescribed across America and there has been less data on the safety [of these antipsychotics at lower doses].”
Dr. Roger S. McIntyre
Dr. McIntyre, chairman and executive director of the Brain and Cognitive Discover Foundation, Toronto, who was not involved with the study, said that this “important report reminds us that there are metabolic safety concerns, even at low doses, where these medications are often used off label.”
He advised clinicians to “seek alternatives, and alternatives that are on-label, for conditions like anxiety and sleep disturbances.”
This work was supported by the South Region Board ALF, Sweden. Dr. Berge and coauthors have disclosed no relevant financial relationships. Dr. McIntyre has received research grant support from CIHR/GACD/Chinese National Natural Research Foundation; and speaker/consultation fees from Lundbeck, Janssen, Purdue, Pfizer, Otsuka, Allergan, Takeda, Neurocrine, Sunovion, Eisai, Minerva, Intra-Cellular, and AbbVie. Dr. McIntyre is CEO of AltMed.
A version of this article first appeared on Medscape.com.