Systematic review and meta-analysis estimating association of cysticercosis and neurocysticercosis with epilepsy

Abstract

Background: We reviewed studies that analyzed cysticercosis (CC), neurocysticercosis (NCC) and epilepsy across Latin America, Asia and Sub-Saharan Africa, to estimate the odds ratio and etiologic fraction of epilepsy due to CC in tropical regions.

Methodology: We conducted a systematic review of the literature on cysticercosis and epilepsy in the tropics, collecting data from case-control and cross-sectional studies. Exposure criteria for CC included one or more of the following: serum ELISA or EITB positivity, presence of subcutaneous cysts (both not verified and unverified by histology), histology consistent with calcified cysts, and brain CT scan consistent with NCC. A common odds-ratio was then estimated using meta-analysis.

Principal findings: 37 studies from 23 countries were included (n = 24,646 subjects, 14,934 with epilepsy and 9,712 without epilepsy). Of these, 29 were case-control (14 matched). The association between CC and epilepsy was significant in 19 scientific articles. Odds ratios ranged from 0.2 to 25.4 (a posteriori power 4.5-100%) and the common odds ratio was 2.7 (95% CI 2.1-3.6, p <0.001). Three subgroup analyses performed gave odds ratios as: 2.2 (EITB-based studies), 3.2 (CT-based studies), 1.9 (neurologist-confirmed epilepsy; door-to-door survey and at least one matched control per case). Etiologic fraction was estimated to be 63% in the exposed group among the population.

Significance: Despite differences in findings, this meta-analysis suggests that cysticercosis is a significant contributor to late-onset epilepsy in tropical regions around the world, and its impact may vary depending on transmission intensity.

Fig 1. Flowchart of literature search.

Fig 2. Locations of studies that evaluated association of cysticercosis and epilepsy.

Fig 3. Meta-analysis assessing the association between CC and epilepsy globally and by continents: OR (odds ratio) of each study and common OR estimated using a random effects model

Fig 4

Various subgroup meta-analyses (EITB: Fig 4A, CT scan: Fig 4b; best studies: Fig 4c) assessing the association between CC and epilepsy in Latin America, Asia and Africa: OR (odds ratio) of each study and common OR estimated using a random effects model.