Malik S, et al. – The aim of this case control study was to investigate the clinical risk factors for neutropenia patients treated with clozapine. The authors identified an affiliation between the concurrent use of sodium valproate and an increased risk of clozapine associated neutropenia. They suggested that the risk of clozapine associated neutropenia could be reduced by avoiding concurrent valproate treatment.

Methods

• It was a case-control study.
• This research was conducted within a database of anonymised electronic clinical records.
• All patients who stopped clozapine due to a neutropenic event were incorporated as cases.
• Matched controls were chosen from patients with a documented clozapine exposure at the time of the clozapine neutropenic event of the case patient, matched by duration of clozapine treatment.

Results

• 136 cases and 136 controls were incorporated in this investigation.
• The concurrent use of sodium valproate was related to neutropenia (Odds Raito (OR) 2.28, 95%CI: 1.27–4.11, p = 0.006) in multivariable analysis.
• Notably, there was a dose-response effect, with greater associations for higher doses.
• The findings suggested that patients who ceased clozapine due to neutropenia were more likely to be of black ethnicity (OR 2.99, p < 0.001), were younger (t = 5.86, df = 267, p < 0.001), and received lower doses of clozapine (t = -2.587, p = 0.01) than those who did not develop neutropenia.