An interdepartmental research team from the LKS Faculty of Medicine, The University of Hong Kong (HKUMed) has conducted the first real-world cohort analytical study on the association of clozapine, a highly effective antipsychotic drug, with cancer incidence. of blood. . Their findings show that the risk of blood cancer associated with clozapine use is very low, with an average increase of less than six cases per 10,000 people who use clozapine over a year. Therefore, the clinical significance of such a risk is plausibly low. While previous preliminary Western studies have shown a potentially significant increased risk, this study suggests that with strict blood control measures before and during clozapine use in Hong Kong and worldwide, it may not be necessary to further restrict the clozapine use or issue problems. special warnings from the Department of Health or local drug regulatory authorities, thus facilitating early and effective treatment of mental illnesses. The study was published in Additional medicine.
Background
Clozapine is currently the only antipsychotic drug approved by the US Food and Drug Administration (FDA) for treatment-resistant schizophrenia. It is widely known for its high efficacy in reducing symptoms, relapse rate, and all-cause mortality in schizophrenia and is widely considered a drug of last resort. Recent Finnish and American studies suggested that clozapine may be associated with a significantly increased risk of blood cancer. However, due to data restrictions and study design, the additional number of blood cancer cases associated with prior exposure to clozapine could not be estimated and was not clear. Therefore, the clinical significance of this risk had not yet been determined.
Research methods and findings.
The research team used electronic medical records from across the Hong Kong Hospital Authority to review 400,000 patient records and construct a retrospective cohort of approximately 10,000 patients diagnosed with schizophrenia between 2001 and 2022 and followed for a median of seven years since its appearance. drug initiation. The team’s observations of the patients showed the following:
- The absolute risk of blood cancer is very rare: In the cohort of 10,000 patients followed over a period of about seven years, only 39 developed blood cancer. After statistical adjustment, the study estimated that there were fewer than six cases of blood cancer for every 10,000 patients using clozapine for one year.
- According to Western studies: The weighted incidence rate of blood cancer in clozapine users versus controls was estimated to be 2.22, suggesting a slight association. This observation is consistent with the findings of previous Finnish and American case-control studies.
- Without risk of other cancers: No association was observed for other cancer types.
Importance of the study
‘In response to Western studies suggesting a potential risk of blood cancer after use of clozapine, this study provides reliable evidence for patients and healthcare professionals supporting the safety of the drug. Current blood control measures are very comprehensive. Patients need not worry too much about the risk of blood cancer caused by clozapine, given the rarity of its occurrence demonstrated in this study. Doctors should weigh the risks and benefits of the drug, taking into account the rarity of the association between clozapine and blood cancer, and take appropriate measures according to patients’ needs,” said Professor Francisco Lai Tsz-tsun, leader of the project and assistant professor in both the Department of Pharmacology and Pharmacy and the Department of Family Medicine and Primary Care of the Faculty of Clinical Medicine of HKUMed.
“With easily linked data available longitudinally across all public health facilities in Hong Kong, we were able to develop a better study design than other countries,” said Professor Lai. “This allowed us to make immediate use of big data to better address clinically significant health issues than researchers in many other countries, highlighting the key strengths of Hong Kong’s big health data and its potential application in health care monitoring.” medications”.
The research team is currently re-examining a wide range of potential adverse effects of other psychotropic drugs, especially cancer risks, and their overall long-term safety and effectiveness. “Ultimately, through our joint interdisciplinary efforts, we hope to better inform everyday clinical decisions and make the use of medications in patients with mental illness much safer and more effective,” Professor Lai added.