Department of Psychological Medicine, University of Otago, Wellington, New Zealand.
Department of Medicine (Gastroenterology), University of Otago, Wellington, New Zealand.
Schizophr Res. 2020 Jun;220:179-186. doi: 10.1016/j.schres.2020.03.032. Epub 2020 Apr 1.
Clozapine is the favoured antipsychotic for treatment-refractory schizophrenia but its safe use requires careful adverse-effect management. Clozapine-induced gastrointestinal hypomotility (CIGH or 'slow-gut') is one of the most common and serious of clozapine's adverse effects. CIGH can lead to paralytic ileus, bowel obstruction, gastrointestinal ischaemia, toxic megacolon, and death. Enquiring about constipation is a simple and commonly used screening method for CIGH but its diagnostic accuracy has not previously been assessed.
First, we examined the reliability of asking about constipation compared with asking about Rome constipation criteria in inpatients treated with clozapine (n = 69). Second, we examined the diagnostic accuracy of (1) self-reported constipation and (2) the Rome criteria, compared with the reference standard of gastrointestinal motility studies.
After 30 motility tests, it was clear constipation screening had very poor diagnostic properties in this inpatient group and the study was terminated. Although 73% of participants had objective CIGH on motility testing, only 26% of participants self-reported constipation, with sensitivity of 18% (95% CI: 5-40%). Specificity and positive predictive values were higher (95% CI: 63-100% and 40-100%, respectively). Adding in Rome criteria improved sensitivity to 50% (95% CI: 28.2-71.8%), but half the cases were still missed, making this no more accurate than tossing a coin.
CIGH is often silent, with self-reported constipation having low sensitivity in its diagnosis. Treating CIGH based on self-reported symptoms questions will miss most cases. However, universal bowel motility studies are impractical. In the interests of patient safety, prophylactic laxatives are suggested for people taking clozapine.
氯氮平是治疗难治性精神分裂症的首选抗精神病药，但安全使用需要谨慎管理不良反应。氯氮平引起的胃肠动力低下（CIGH 或“慢肠”）是氯氮平最常见和最严重的不良反应之一。CIGH 可导致麻痹性肠梗阻、肠梗阻、胃肠缺血、中毒性巨结肠和死亡。询问便秘是一种简单且常用的 CIGH 筛查方法，但尚未评估其诊断准确性。
首先，我们比较了询问便秘与询问罗马便秘标准在接受氯氮平治疗的住院患者中的可靠性（n=69）。其次，我们比较了（1）自我报告的便秘和（2）罗马标准与胃肠动力研究参考标准的诊断准确性。
在 30 次动力测试后，很明显，在该住院患者组中，便秘筛查的诊断特性很差，研究因此终止。尽管 73%的参与者在动力测试中存在客观的 CIGH，但只有 26%的参与者自我报告便秘，其敏感性为 18%（95%CI：5-40%）。特异性和阳性预测值更高（95%CI：63-100%和 40-100%）。添加罗马标准可将敏感性提高至 50%（95%CI：28.2-71.8%），但仍有一半的病例被遗漏，这并不比掷硬币更准确。
CIGH 通常是无症状的，自我报告的便秘对其诊断的敏感性较低。根据自我报告的症状进行治疗将错过大多数病例。然而，进行普遍的肠动力研究是不切实际的。为了患者安全，建议服用氯氮平的患者预防性使用泻药。
