BMC Psychiatry (Aug 2024)

Developing a validated methodology for identifying clozapine treatment periods in electronic health records

  • Aviv Segev,
  • Risha Govind,
  • Ebenezer Oloyede,
  • Hamilton Morrin,
  • Amelia Jewell,
  • Rowena Jones,
  • Laura Mangiaterra,
  • Stefano Bonora,
  • Ehtesham Iqbal,
  • Robert Stewart,
  • Matthew Broadbent,
  • James H. MacCabe

DOI
https://doi.org/10.1186/s12888-024-06022-5
Journal volume & issue
Vol. 24, no. 1
pp. 1 – 12

Abstract

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Abstract Background Clozapine is the only recommended antipsychotic medication for individuals diagnosed with treatment-resistant schizophrenia. Unfortunately, its wider use is hindered by several possible adverse effects, some of which are rare but potentially life threatening. As such, there is a growing interest in studying clozapine use and safety in routinely collected healthcare data. However, previous attempts to characterise clozapine treatment have had low accuracy. Aim To develop a methodology for identifying clozapine treatment dates by combining several data sources and implement this on a large clinical database. Methods Non-identifiable electronic health records from a large mental health provider in London and a linked database from a national clozapine blood monitoring service were used to obtain information regarding patients' clozapine treatment status, blood tests and pharmacy dispensing records. A rule-based algorithm was developed to determine the dates of starting and stopping treatment based on these data, and more than 10% of the outcomes were validated by manual review of de-identified case note text. Results A total of 3,212 possible clozapine treatment periods were identified, of which 425 (13.2%) were excluded due to insufficient data to verify clozapine administration. Of the 2,787 treatments remaining, 1,902 (68.2%) had an identified start-date. On evaluation, the algorithm identified treatments with 96.4% accuracy; start dates were 96.2% accurate within 15 days, and end dates were 85.1% accurate within 30 days. Conclusions The algorithm produced a reliable database of clozapine treatment periods. Beyond underpinning future observational clozapine studies, we envisage it will facilitate similar implementations on additional large clinical databases worldwide.

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