Iron homeostasis alterations and risk for akathisia in patients treated with antipsychotics: A systematic review and meta-analysis of cross-sectional studies.

Iron homeostasis may be implicated in the pathophysiology of antipsychotic-related akathisia. We performed a systematic review in six databases from database inception until 03/2020, conducting a meta-analysis of studies investigating iron metabolism in antipsychotic-treated patients with versus without akathisia. Using a fixed- and a random-effects model, standardized mean difference (SMD) was estimated for levels of iron, ferritin, transferrin and total iron-binding capacity. Meta-regression analyses included sex, age, illness duration and antipsychotic treatment and dose. Subgroup analyses included chronic vs. acute akathisia and different diagnoses. Study quality was assessed using the Newcastle-Ottawa scale. In 10 studies (n = 395), compared to non-akathisia patients (n = 213), iron levels were lower in patients with akathisia (n = 182; fixed-effect model: SMD=-0.49, 95%CI=-0.28,-0.70, p<0.001; random-effects model: SMD=-0.55, 95%CI=-0.14,-0.96, p = 0.008). For secondary outcomes, differences were significant regarding lower ferritin levels in patients with akathisia in the fixed-effect model (SMD=-0.32, 95%CI=-0.08,-0.55, p = 0.007), but not in the random-effects model (SMD=-0.29, 95%CI=0.20,-0.79, p = 0.24). None of the moderators/mediators had a significant effect on the group difference of iron levels. Subgroup analyses reported lower iron levels in both patients with chronic and acute akathisia vs. patients without. Iron levels for schizophrenia patients were lower in the fixed-effect model (SMD=-0.55, 95%CI=-0.23, -0.86, p<0.001), while a trend was observed in the random-effects model (SMD=-0.52, 95%CI=-0.07, -1.12, p = 0.08). The studies' quality was overall poor, with one exception. This meta-analysis suggests lower iron levels in akathisia patients, while ferritin differences were significant only in the fixed-effect model. Further data are required to promote the understanding of related pathways.