Background and Hypothesis In response to Health Canada’s March 2020 directive, patients on clozapine for over 12 months were allowed to extend hematological testing intervals from 4 to 8 weeks during the COVID-19 pandemic. We hypothesized that this change would not affect the timely detection of hematological abnormalities in patients with severe mental illness. Study Design A chart review was conducted of patients at the Royal Ottawa who were prescribed clozapine from March 2019 to March 2021. We analyzed clinical and hematological data from electronic health records and Clozaril Support and Assistance Network database to compare occurrences of hematological abnormalities [leukopenia (white blood cell count <3.5 × 109/L) and agranulocytosis (absolute neutrophil count <0.5 × 109/L)] from March 17, 2020 to March 16, 2021, between standard and extended monitoring protocols using binomial logistic and zero-inflated negative binomial regressions. Study Results Of 621 patients, 196 were on extended blood monitoring, and 425 followed standard blood monitoring. Clozapine dose did not differ between groups (standard: 370 ± 201 mg; extended: 352 ± 172 mg; P = .14, ds = 0.10). Clozapine treatment duration up to March 2021 was 12.6 ± 8.3 years, with the extended group (10 ± 7.9 years) having a significantly (P < .01, ds = 0.50) shorter duration than the standard (14 ± 8.2 years). Extended monitoring did not significantly impact likelihood of detecting hematological abnormalities (OR = 0.83, 95% CI [0.58,1.41], P = .55) after controlling for age, sex, total bloodwork, and other psychotropics associated with neutrophil counts (ie, valproate, olanzapine). No patient on the extended regimen developed agranulocytosis. Conclusions Reducing blood monitoring frequency in patients on clozapine for more than 12 months did not compromise detection of hematological abnormalities.

中文翻译：

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评估氯氮平治疗的精神分裂症患者血液监测频率降低和血液学异常检测：来自 COVID-19 大流行的图表回顾研究


背景和假设 为了响应加拿大卫生部 2020 年 3 月的指令，在 COVID-19 大流行期间，允许服用氯氮平超过 12 个月的患者将血液学检测间隔从 4 周延长至 8 周。我们假设这种变化不会影响严重精神疾病患者血液学异常的及时发现。研究设计 对 2019 年 3 月至 2021 年 3 月期间在皇家渥太华接受氯氮平治疗的患者进行了图表回顾。我们分析了来自电子健康记录和 Clozaril 支持和援助网络数据库的临床和血液学数据，以比较血液学异常的发生率 [白细胞减少症 （白细胞计数 <3.5 × 109/L） 和粒细胞缺乏症 （绝对中性粒细胞计数 <0.5 × 109/L）] 从 2020年3月17日至2021年3月16日，使用二项式 logistic 和零充气阴性二项式回归的标准和扩展监测方案。研究结果 在 621 名患者中，196 名接受了扩展血液监测，425 名接受了标准血液监测。氯氮平剂量组间无差异（标准：370 ± 201 mg;扩展剂量：352 ± 172 mg;P = .14，ds = 0.10）。截至 2021 年 3 月的氯氮平治疗持续时间为 12.6 ± 8.3 年，延长组 （10 ± 7.9 年） 的持续时间显著短于标准 （14 ± 8.2 年）。在控制年龄、性别、总血液检查和其他与中性粒细胞计数相关的精神药物（即丙戊酸盐、奥氮平）后，扩展监测对检测血液学异常的可能性没有显著影响（OR=0.83,95% CI [0.58,1.41]，P=.55）。延长方案组的患者未发生粒细胞缺乏症。 结论 降低氯氮平患者超过 12 个月的血液监测频率并不影响血液学异常的检测。