Selective Immunoglobulin M Deficiency Among Clozapine-Treated Patients: A Nested Case-Control Study

Area of Science:

• Immunology
• Psychiatry
• Pharmacology

Background:

• Clozapine is an effective antipsychotic for treatment-resistant schizophrenia.
• Immunodeficiency, specifically selective immunoglobulin M immunodeficiency (SIgMD), can occur in patients undergoing long-term psychiatric medication.
• The relationship between clozapine use and SIgMD requires further investigation.

Purpose of the Study:

• To investigate the prevalence of SIgMD in outpatients receiving long-term clozapine therapy.
• To determine if there is a statistically significant association between clozapine treatment and the development of SIgMD.

Main Methods:

• A nested case-control study was conducted between January 2009 and December 2013.
• 33 clozapine-treated patients were assessed for SIgMD (defined as mean IgM ≤ 30 mg/dL).
• Cases with SIgMD were compared to controls without SIgMD, matched for demographic and clinical factors.

Main Results:

• Six out of 33 clozapine-treated patients (18.2%) were diagnosed with SIgMD.
• A significant association was found between clozapine use and SIgMD (OR = 7.2222, P = .0197).
• 75% of patients with SIgMD had taken clozapine, compared to 29% in the non-SIgMD group.

Conclusions:

• Clozapine treatment is associated with a significantly higher risk of developing SIgMD.
• Clinicians should monitor IgM levels in patients treated with clozapine, in addition to granulocyte counts.
• Proactive monitoring of IgM decline may help prevent iatrogenic complications in patients on clozapine therapy.