Validation of the Indonesian Brief Screening Instrument for Epilepsy

Evaluating Sensitivity and False-Positive Rates in Epilepsy Screening

To assess how effectively the screening tool performed diagnostically, the team of researchers delivered the nine telephone-based questions across three separate cohorts. Data released from the study reveal that the total cohort comprised 120 participants verified as seizure-free via medical charts, 54 subjects who had experienced one unprovoked seizure, and 168 individuals with documented medical records confirming epilepsy, defined as having a history of at least two unprovoked seizures over their lifetime. Interviewers conducting these telephone calls remained strictly blinded to the record-review findings.

The validated instrument achieved a sensitivity of 96% for identifying epilepsy and an 87% sensitivity for detecting isolated unprovoked seizures, according to the published findings. Sensitivity represents the proportion of affected individuals who correctly screen positive. Meanwhile, the false-positive rate—defined as the proportion of seizure-free individuals who incorrectly screened positive—stood at 7%. Assuming a lifetime population prevalence of 2%, researchers calculated the positive predictive value for epilepsy at 23%, establishing that establishing that roughly one in four screen-positive individuals will be truly affected.

Comparing Single-Question Versus Multi-Question Approaches

The study additionally evaluated the effectiveness of a streamlined approach that relied on a solitary query: inquiring whether participants had ever suffered from a seizure condition or epilepsy. Utilizing this single inquiry produced markedly different statistical outcomes compared to the comprehensive nine-question battery, as detailed in the study data.

Data showed that the single-question approach yielded a sensitivity of 76% and a lower false-positive rate of 0.8%. However, the estimated positive predictive value for the single question rose to 66%. Researchers noted that study participants with epilepsy were more likely to screen positive on the single question if they were diagnosed after 1964 or if their active seizures continued for five years or more following their initial diagnosis.

Implications for Epidemiological and Genetic Research

A major hurdle in conducting large genetic mappings and population-wide epidemiological studies is reliably pinpointing people who have experienced seizures. Traditional population studies frequently rely on comprehensive medical record reviews or broad questionnaires that capture symptoms like unprovoked seizures, though these tools often balance high sensitivity against high false-positive rates, creating downstream economic and logistical hurdles for researchers.

Historically, large-scale epidemiological frameworks have frequently deployed two-stage screening strategies involving an initial broad screen followed by detailed assessments to separate true from false positives. Earlier multi-item questionnaires frequently incorporated symptom-based inquiries—such as asking whether a patient has ever experienced attacks involving a loss of contact with surroundings—to maximize sensitivity in settings with limited access to medical care. While those broad questionnaires achieved sensitivity rates of 95% or higher, they typically incurred lower specificity, directly impacting positive predictive value and increasing the effort and cost involved in a study.