Department of Epidemiology, Brown University School of Public Health, Providence, Rhode Island, United States of America.
Department of Biostatistics and Data Science, University of Texas Health Science Center at Houston, Texas, United States of America.
PLoS Negl Trop Dis. 2019 Jan 17;13(1):e0007109. doi: 10.1371/journal.pntd.0007109. eCollection 2019 Jan.
Epilepsy and progressively worsening severe chronic headaches (WSCH) are the two most common clinical manifestations of neurocysticercosis, a form of cysticercosis. Most community-based studies in sub-Saharan Africa (SSA) use a two-step approach (questionnaire and confirmation) to estimate the prevalence of these neurological disorders and neurocysticercosis. Few validate the questionnaire in the field or account for the imperfect nature of the screening questionnaire and the fact that only those who screen positive have the opportunity to be confirmed. This study aims to obtain community-based validity estimates of a screening questionnaire, and to assess the impact of verification bias and misclassification error on prevalence estimates of epilepsy and WSCH.
METHODOLOGY/PRINCIPAL FINDINGS: Baseline screening questionnaire followed by neurological examination data from a cluster randomized controlled trial collected between February 2011 and January 2012 were used. Bayesian latent-class models were applied to obtain verification bias adjusted validity estimates for the screening questionnaire. These models were also used to compare the adjusted prevalence estimates of epilepsy and WSCH to those directly obtained from the data (i.e. unadjusted prevalence estimates). Different priors were used and their corresponding posterior inference was compared for both WSCH and epilepsy. Screening data were available for 4768 individuals. For epilepsy, posterior estimates for the sensitivity varied with the priors used but remained robust for the specificity, with the highest estimates at 66.1% (95%BCI: 56.4%;75.3%) for sensitivity and 88.9% (88.0%;89.8%) for specificity. For WSCH, the sensitivity and specificity estimates remained robust, with the highest at 59.6% (49.7%;69.1%) and 88.6% (87.6%;89.6%), respectively. The unadjusted prevalence estimates were consistently lower than the adjusted prevalence estimates for both epilepsy and WSCH.
CONCLUSIONS/SIGNIFICANCE: This study demonstrates that in some settings, the prevalence of epilepsy and WSCH can be considerably underestimated when using the two-step approach. We provide an analytic solution to obtain more valid prevalence estimates of these neurological disorders, although more community-based validity studies are needed to reduce the uncertainty of the estimates. Valid estimates of these two neurological disorders are essential to obtain accurate burden values for neglected tropical diseases such as neurocysticercosis that manifest as epilepsy or WSCH.
ClinicalTrials.gov NCT03095339.
癫痫和逐渐加重的严重慢性头痛（WSCH）是神经囊尾蚴病（囊尾蚴病的一种形式）的两种最常见的临床症状。撒哈拉以南非洲（SSA）的大多数基于社区的研究使用两步法（问卷和确认）来估计这些神经系统疾病和神经囊尾蚴病的患病率。很少有研究在现场验证问卷，也没有考虑到筛查问卷的不完善性质，以及只有那些筛查呈阳性的人有机会得到确认。本研究旨在获得基于社区的筛查问卷的有效性估计，并评估验证偏差和分类错误对癫痫和 WSCH 患病率估计的影响。
方法/主要发现：使用 2011 年 2 月至 2012 年 1 月期间收集的一项集群随机对照试验中的基线筛查问卷和随后的神经检查数据。应用贝叶斯潜在类别模型获得筛查问卷的验证偏差调整有效性估计。这些模型还用于比较调整后的癫痫和 WSCH 患病率估计值与直接从数据中获得的估计值（即未调整的患病率估计值）。使用了不同的先验，并比较了它们对 WSCH 和癫痫的后验推断。共有 4768 人接受了筛查。对于癫痫，敏感性的后验估计值随所使用的先验值而变化，但特异性仍然稳健，最高估计值为 66.1%（95%BCI：56.4%；75.3%），特异性为 88.9%（88.0%；89.8%）。WSCH 的敏感性和特异性估计值仍然稳健，最高值分别为 59.6%（49.7%；69.1%）和 88.6%（87.6%；89.6%）。未调整的患病率估计值始终低于癫痫和 WSCH 的调整后的患病率估计值。
结论/意义：本研究表明，在某些情况下，使用两步法可能会大大低估癫痫和 WSCH 的患病率。我们提供了一种分析解决方案，以获得这些神经系统疾病更有效的患病率估计值，尽管还需要更多的基于社区的有效性研究来降低估计值的不确定性。这些两种神经系统疾病的有效估计值对于获得神经囊尾蚴病等被忽视的热带病的准确负担值至关重要，这些疾病表现为癫痫或 WSCH。
ClinicalTrials.gov NCT03095339。
