Hiding from danger, not from fear: Lockdown as a risk factor of probable PTSD among civilians after Strasbourg Christmas market terror attack.

On December 11, 2018, five people were killed and 11 injured during a terrorist attack on Strasbourg's Christmas market. As the attacker was on the run during the night, part of the population was locked down for several hours. Our study aimed at assessing factors associated with the development of PTSD and health services use among the victims. Four hundred and twelve victims were followed up from 6 to 11 months after the attacks through phone calls by psychologists. The presence of probable PTSD was assessed with the Trauma Screening Questionnaire. In addition, we evaluated the type and level of exposure, and health services use after the attacks. Two hundred and twelve participants completed the phone interview. The prevalence of probable PTSD was 26.4%. Being locked down during the attack and the level of exposure were associated with probable PTSD (OR = 2.32 [1.17-4.59], p = 0.016 and OR = 1.49 [1.10-2.03], p = 0.010 respectively). Lockdown was especially associated with symptoms suggesting adrenergic hyperactivation (startle at surprise, dreams about the event). General and mental health services use was frequent among our sample (83% consulted either their GP or a mental health professional), but people living alone tend to use these health services more infrequently than these living with others. Though necessary, measures taken to protect victims, such as lockdown, may foster PTSD. Victims of terror attacks having been subjected to lockdown may have experienced powerlessness, fostering prolonged stress and fear. These victims may benefit from mental health support over the following months.