Psychiatric Diagnosis as an Independent Risk Factor for Metabolic Disturbances: Results From a Comprehensive, Naturalistic Screening Program

Objective: Unconfounded differences in inherent vulnerability to metabolic disturbance may be hypothesized for different diagnostic groups with severe mental illness.

Method: A naturalistic cohort of patients diagnosed with DSM-IV bipolar disorder (N = 112), schizophrenia (N = 503), and schizoaffective disorder (N = 92) were assessed for metabolic disturbances. The prospective inclusions started in November 2003 and were concluded in July 2007.

Results: Diagnosis was strongly associated with the metabolic syndrome (chi² = 14.90, df = 2, p < .001). Compared with bipolar patients, the unadjusted risk for metabolic syndrome was significantly higher for schizoaffective (odds ratio [OR] = 3.51, p < .0001) but not for schizophrenia patients (OR = 1.58, p = .094). Differences were not reducible to confounding factors including treatment. Rather, the difference between bipolar and schizophrenia patients also reached significance after adjustment (OR = 1.97, p = .046). Furthermore, the association between diagnosis and glucose dysregulation was significant (chi² = 6.97, df = 2, p = .031), with a significantly higher risk in schizoaffective (unadjusted OR = 2.12, p = .022) but not in schizophrenia patients (unadjusted OR = 1.13, p = .640) compared with bipolar patients. Diagnostic differences in glucose dysregulation were in part mediated by body mass index (BMI).

Conclusions: Schizoaffective patients in particular may be at risk for metabolic disturbances compared with bipolar and schizophrenia patients. Differences were not reducible to known metabolic risk factors and could only be explained in part by higher BMI in schizoaffective patients, suggesting an increased inherent vulnerability in this group.