Background: Despite its popularity, evidence of the effectiveness of Psychological First Aid (PFA) is scarce.Objective: To assess whether PFA, compared to psychoeducation (PsyEd), an attention placebo control, reduces PTSD and depressive symptoms three months post-intervention.Methods: In two emergency departments, 166 recent-trauma adult survivors were randomised to a single session of PFA (n = 78) (active listening, breathing retraining, categorisation of needs, assisted referral to social networks, and PsyEd) or stand-alone PsyEd (n = 88). PTSD and depressive symptoms were assessed at baseline (T0), one (T1), and three months post-intervention (T2) with the PTSD Checklist (PCL-C at T0 and PCL-S at T1/T2) and the Beck Depression Inventory-II (BDI-II). Self-reported side effects, post-trauma increased alcohol/substance consumption and interpersonal conflicts, and use of psychotropics, psychotherapy, sick leave, and complementary/alternative medicine were also explored.Results: 86 participants (51.81% of those randomised) dropped out at T2. A significant proportion of participants in the PsyEd group also received PFA components (i.e. contamination). From T0 to T2, we did not find a significant advantage of PFA in reducing PTSD (p = .148) or depressive symptoms (p = .201). However, we found a significant dose-response effect between the number of delivered components, session duration, and PTSD symptom reduction. No significant difference in self-reported adverse effects was found. At T2, a smaller proportion of participants assigned to PFA reported increased consumption of alcohol/substances (OR = 0.09, p = .003), interpersonal conflicts (OR = 0.27, p = .014), and having used psychotropics (OR = 0.23, p = .013) or sick leave (OR = 0.11, p = .047).Conclusions: Three months post-intervention, we did not find evidence that PFA outperforms PsyEd in reducing PTSD or depressive symptoms. Contamination may have affected our results. PFA, nonetheless, appears to be promising in modifying some post-trauma behaviours. Further research is needed. Psychological First Aid (PFA) is widely recommended early after trauma.We assessed PFA's effectiveness for decreasing PTSD symptoms and other problems 3 months post-trauma.We didn't find definitive evidence of PFA's effectiveness. Still, it seems to be a safe intervention. Antecedentes: A pesar de su popularidad, la evidencia sobre la efectividad de los Primeros Auxilios Psicol & oacute;gicos (PAP) es escasa.Objetivo: Evaluar si los PAP, en comparaci & oacute;n con la psicoeducaci & oacute;n (PsiEd), un control de placebo atencional, reducen los s & iacute;ntomas de PTSD y depresi & oacute;n tres meses despu & eacute;s de la intervenci & oacute;n.M & eacute;todo: En dos servicios de urgencia, 166 adultos sobrevivientes de traumas recientes fueron asignados aleatoriamente a una sola sesi & oacute;n de PAP (n = 78) (escucha activa, ejercicios de respiraci & oacute;n, categorizaci & oacute;n de necesidades, derivaci & oacute;n asistida a redes sociales y PsiEd) o a PsiEd sola (n = 88). Los s & iacute;ntomas de PTSD y depresi & oacute;n fueron evaluados al inicio (T0), uno (T1) y tres meses despu & eacute;s de la intervenci & oacute;n (T2) con el PTSD Checklist (PCL-C en T0 y PCL-S en T1/T2) y el Inventario de Depresi & oacute;n de Beck-II (BDI-II). Tambi & eacute;n se explor & oacute; el autoreporte de efectos adversos, consumo de alcohol/sustancias, conflictos interpersonales, y uso de psicotr & oacute;picos, psicoterapia, licencia por enfermedad y medicina complementaria/alternativa.Resultados: 86 participantes (51,81% de los aleatorizados) abandonaron en T2. Una proporci & oacute;n significativa de participantes en el grupo PsiEd tambi & eacute;n recibi & oacute; componentes de PAP (es decir, hubo contaminaci & oacute;n). De T0 a T2, no encontramos una ventaja significativa de PAP en la reducci & oacute;n de s & iacute;ntomas de PTSD (p = .148) o depresi & oacute;n (p = .201). Sin embargo, encontramos un efecto dosis-respuesta significativo entre el n & uacute;mero de componentes entregados o la duraci & oacute;n de la sesi & oacute;n y la reducci & oacute;n de s & iacute;ntomas de PTSD. No encontramos diferencias significativas en efectos adversos. En T2, una proporci & oacute;n menor de participantes asignados a PAP report & oacute; un aumento en el consumo de alcohol/sustancias (OR = 0.09, p = .003), conflictos interpersonales (OR = 0.27, p = .014), y uso de psicotr & oacute;picos (OR = 0.23, p = .013) o licencia por enfermedad (OR = 0.11, p = .047).Conclusiones: Tres meses despu & eacute;s de la intervenci & oacute;n, no encontramos evidencia de que los PAP superen a PsiEd en la reducci & oacute;n de s & iacute;ntomas de PTSD o depresi & oacute;n. La contaminaci & oacute;n pudo haber afectado nuestros resultados. Sin embargo, los PAP parecen ser prometedores en la modificaci & oacute;n de algunos comportamientos postraum & aacute;ticos. Se necesita m & aacute;s investigaci & oacute;n.
