Baseline imbalances and clinical outcomes of atypical antipsychotics in dementia: A meta-epidemiological study of randomized trials

Abstract

Objectives: To assess baseline imbalances in placebo-controlled trials of atypical antipsychotics in dementia, and their association with neuropsychiatric symptoms (NPS), extrapyramidal symptoms (EPS), and mortality.

Method: We searched for trials in multiple sources. Two reviewers extracted baseline characteristics and outcomes per treatment group. We calculated direction, range, pooled mean, and heterogeneity in the baseline differences, and used meta-regression for the relationship with the outcomes.

Results: We identified 23 trials. Baseline type of dementia, cognitive impairment and NPS were poorly reported. The drug group had a higher mean age than the placebo group in nine trials and lower mean age in three trials (p = 0.073). The difference in percentage men between the drug and placebo group ranged from -9.7% to 4.4%. There were no statistically significant pooled baseline differences, but heterogeneity was present for age. Higher mean age at baseline in the drug versus placebo group was significantly associated with greater reduction in NPS, and higher percentage of non-White persons with lower risk of EPS. Imbalances were not significantly associated with risk of mortality.

Conclusion: Randomized trials of atypical antipsychotics in dementia showed baseline imbalances that were associated with higher efficacy and lower risk of EPS for atypical antipsychotics versus placebo.

Keywords: antipsychotics; baseline imbalances; bias; meta-regression; trials.

Figure 1

Flow diagram of literature search and study selection

Figure 2

Treatment versus control group size differences and total trial size for 17 unrestricted trials, with expected distributions for 50% and 95% (dotted) prediction intervals