The majority of the screening questionnaires for epilepsy have been validated in hospital settings. This research team previously developed and used for field-validation a screening tool to detect generalized tonic-clonic seizures (GTCS) in the rural communities of the Chaco region of Bolivia. The objective of the present study was to perform a hospital-based validation of the same questionnaire and to compare the levels of accuracy obtained when validated in the field or in a hospital-based context.
The team carried out a hospital-based validation in the Hospital Hernandez Vera of Santa Cruz, Bolivia where we enrolled subjects affected by epilepsy with GTCS and control subjects. Sensitivity, and specificity, positive and negative predictive values (PPV and NPV) were calculated.
120 questionnaires were administered to 59 patients (27 men [45.8%]; mean age 32.4 ± 14.2 years) and 61 controls (27 men [44.3%]; mean age 32.6 ± 14.3 years). Researchers obtained levels of accuracy of 100%. Sensitivity and positive predictive value were significantly higher than the estimates obtained in the field?validation study (sensitivity 100% versus 76.3%; PPV 100% versus 69.0%).
The screening questionnaire showed a significantly lower level of sensitivity when validated in the field, confirming that hospital?based validation can lead to an overestimation of sensitivity.