OBJECTIVE 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. METHODS 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. RESULTS 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. CONCLUSIONS 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.

中文翻译：

---

对服用氯氮平的人进行便秘筛查：一项诊断准确性研究

目的 氯氮平是治疗难治性精神分裂症的首选抗精神病药，但其安全使用需要谨慎的不良反应管理。氯氮平引起的胃肠动力减退（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、胃肠道缺血、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，但之前尚未评估其诊断准确性。方法 首先，我们检查了在接受氯氮平治疗的住院患者（n = 69）中询问便秘与询问罗马便秘标准的可靠性。其次，我们检查了（1）自我报告的便秘和（2）罗马标准的诊断准确性，与胃肠动力研究的参考标准进行比较。结果 在 30 次运动测试后，很明显便秘筛查在该住院组中的诊断性能非常差，因此研究终止。尽管 73% 的参与者在运动性测试中具有客观的 CIGH，但只有 26% 的参与者自我报告便秘，敏感性为 18%（95% CI：5-40%）。特异性和阳性预测值更高（95% CI：分别为 63-100% 和 40-100%）。添加罗马标准将灵敏度提高到 50%（95% CI：28.2-71.8%），但仍有一半的案例被遗漏，这使得这并不比抛硬币更准确。结论 CIGH 通常是沉默的，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问题治疗 CIGH 会漏掉大多数病例。然而，普遍的肠蠕动研究是不切实际的。为了患者安全，建议服用氯氮平的患者使用预防性泻药。