Redefining peripheral inflammation signature in schizophrenia based on the real-world FACE-SZ cohort

Peripheral inflammation is associated with impaired prognosis in schizophrenia (SZ). Highly sensitive C-reactive protein (hs-CRP) is the most used inflammatory biomarker in daily practice. However, no consensual cut-off has been determined to date to discriminate patients with peripheral inflammation from those without.

To determine if patients with peripheral inflammation between 1 and 3 mg/L had poorer outcomes compared to those with undetectable CRP (<1 mg/L).

Consecutive participants of the FACE-SZ cohort with a hs-CRP < 3 mg/L were included in 10 expert academic centers with a national geographical distribution between 2010 and 2018. Potential sources of inflammation, socio-demographics, illness characteristics, current illness severity, functioning and quality of life and were reported following the FACE-SZ standardized protocol.

580 patients were included, of whom 226 (39%) were identified with low-grade inflammation defined by a hs-CRP between 1 and 3 mg/L. Overweight and lack of dental care were identified as potential sources of inflammation. After adjustment for these factors, patients with inflammation had more severe psychotic, depressive and aggressive symptomatology and impaired functioning compared to the patients with undetectable hs-CRP. No association with tobacco smoking or physical activity level has been found.

Patients with schizophrenia with hs-CRP level between 1 and 3 mg/L should be considered at risk for inflammation-associated disorders. Lowering weight and increasing dental care may be useful strategies to limit the sources of peripheral inflammation. Hs-CRP > 1 mg/L is a reliable marker to detect peripheral inflammation in patients with schizophrenia.