RT Journal Article SR Electronic T1 Value of witness observations in the differential diagnosis of transient loss of consciousness JF Neurology JO Neurology FD Lippincott Williams & Wilkins SP e895 OP e904 DO 10.1212/WNL.0000000000007017 VO 92 IS 9 A1 Chen, Min A1 Jamnadas-Khoda, Jenny A1 Broadhurst, Mark A1 Wall, Melanie A1 Grünewald, Richard A1 Howell, Stephen J.L. A1 Koepp, Matthias A1 Parry, Steve W. A1 Sisodiya, Sanjay M. A1 Walker, Matthew A1 Hesdorffer, Dale A1 Reuber, Markus YR 2019 UL http://n.neurology.org/content/92/9/e895.abstract AB Objective This retrospective study explores to what extent additional information from event witnesses provided using the novel 31-item Paroxysmal Event Observer (PEO) Questionnaire improves the differentiation among epilepsy, syncope, and psychogenic nonepileptic seizures (PNES) achievable with information provided by patients alone.Methods Patients with transient loss of consciousness caused by proven epilepsy (n = 86), syncope (n = 79), or PNES (n = 84) attending specialist neurology/syncope services in the United Kingdom and event observers provided Paroxysmal Event Profile (PEP), PEO, and personal information (PI) (e.g., sex, age, medical history) data. PEO data were subjected to exploratory factor analysis (EFA) followed by confirmatory factor analysis (CFA). PEO, PEP, and PI data were used separately and in combination to differentiate diagnoses by pairwise and multinomial logistic regressions. Predicted diagnoses were compared with gold standard medical diagnoses.Results EFA/CFA identified a 4-factor structure of the PEO based on 26/31 questionnaire items with loadings ≥0.4. Observer-reported factors alone differentiated better between syncope and epilepsy than patient-reported factors (accuracy: 96% vs 85%, p = 0.0004). Observer-reported data improved accuracy over differentiation based on patient-reported data alone from 90% to 100% between syncope and epilepsy (p = 0.005), 76% to 83% between epilepsy and PNES (p = 0.006), and 93% to 95% between syncope and PNES (p = 0.098).Conclusions Information from observers can make an important contribution to the differentiation of epilepsy from syncope or PNES but adds less to that of syncope from PNES.ANOVA=analysis of variance; CFI=comparative fit index; EFA=exploratory factor analysis; PEO=Paroxysmal Event Observer; PEP=Paroxysmal Event Profile; PI=patient information; PNES=psychogenic nonepileptic seizures; RMSEA=root mean square error approximation; TLI=Tucker Lewis index; TLOC=transient loss of consciousness