Browsing by Author "Hauser, Willard Allen"

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A multistate joint model for interval-censored event-history data subject to within-unit clustering and informative missingness, with application to neurocysticercosis research
(2020) Zhang, Hongbin; Kelvin, Elizabeth; Carpio Rodas, Luis Arturo; Hauser, Willard Allen
We propose a multistate joint model to analyze interval-censored event-history data subject to within-unit clustering and nonignorable missing data. The model is motivated by a study of the neurocysticercosis (NC) cyst evolution at the cyst-level, taking into account the multiple cysts phases with intermittent missing data and loss to follow-up, as well as the intra-brain clustering of observations made on a predefined data collection schedule. Of particular interest in this study is the description of the process leading to cyst resolution, and whether this process varies by antiparasitic treatment. The model uses shared random effects to account for within-brain correlation and to explain the hidden heterogeneity governing the missing data mechanism. We developed a likelihood-based method using a Monte Carlo EM algorithm for the inference. The practical utility of the methods is illustrated using data from a randomized controlled trial on the effect of antiparasitic treatment with albendazole on NC cysts among patients from six hospitals in Ecuador. Simulation results demonstrate that the proposed methods perform well in the finite sample and misspecified models that ignore the data complexities could lead to substantial biases.
New understanding about the relationship among neurocysticercosis, seizures, and epilepsy
(2021) Romo, Mateo
Epilepsy and neurocysticercosis are common neurological disorders and are major public health issues that contribute to the world's burden of disease. Acute symptomatic seizures, the main clinical manifestation of parenchymal neurocysticercosis, are caused by the host brain immune-inflammatory process in response to the death or degenerative phase of the parasite. Seizures may recur over the course of several months while the local inflammatory activity lasts. If the seizures recur once the acute process resolves, the patient can be diagnosed as having epilepsy. However, most acute symptomatic seizures secondary to neurocysticercosis do not evolve to epilepsy. Recent prospective studies suggest that the development of epilepsy, while more common than in the general population, is not as common in neurocysticercosis patients as originally suggested by cross-sectional studies. Antiparasitic treatment has been found to hasten the transition of cysts from the active phase to the degenerative phase and is associated with a short-term reduction in focal seizures after treatment. However, antiparasitic treatment has not been found to affect the transition from the degenerative phase to calcification, which is an epileptogenic substrate associated with subsequent epilepsy. In this narrative review, we critically appraise the relationship among neurocysticercosis, seizures, and epilepsy in the context of new developments in the literature.