CRP and major depressive disorder: Although some studies have reported inconsistent results (Gialluisi et al., 2020; Miller, 2020), a meta-analysis of 37 studies which examined the prevalence of low-grade inflammation in depression, using different c-reactive protein (CRP) levels, found that approximately one-in-four patients with depression showed CRP levels >3 mg/l, while three patients out of five had mildly elevated CRP (>1 mg/l) levels (Osimo et al., 2019).