The Epidemiology of Post-Traumatic Stress Disorder after Disasters

Traumatic experiences are relatively common. More than two thirds of persons in the general population may experience a significant traumatic event at some point in their lives, and up to one fifth of people in the United States may experience such an event in any given year (1–5). Although comparable international data are limited, large proportions of populations in many countries have been exposed to terrorism, forced relocation, and violence, which suggests that the overall prevalence of exposure to traumatic events worldwide may be even higher than that in the United States (6, 7). Disasters (e.g., floods, transportation accidents) are traumatic events that are experienced by many people and may result in a wide range of mental and physical health consequences (8). In one survey of US residents, 13 percent of the sample reported a lifetime exposure to natural or human-generated disaster (9). In the National Comorbidity Survey, 18.9 percent of men and 15.2 percent of women reported a lifetime experience of a natural disaster (4). Post-traumatic stress disorder (PTSD) is the most commonly studied and probably the most frequent and debilitating psychological disorder that occurs after traumatic events and disasters (8, 10). The growing threat of terrorism worldwide has heightened our awareness of disasters as a potentially important determinant of population health and suggests a pressing need both to identify key areas of consensus in postdisaster research and to highlight areas that require additional study (11). It is our purpose in this review to contribute to this overall goal by comprehensively and systematically assessing the epidemiologic evidence about PTSD after disasters. We limited this review to studies conducted between 1980, when PTSD was first codified as a disorder in the Diagnostic and Statistical Manual of Mental Disorders (DSM), Third Edition (DSM-III) (12), and 2003. Although we limited this review to studies conducted after 1980, there is a substantial body of literature preceding that date, and this research had a profound influence on the empirical work that is reviewed here. Much of this work sought to understand the psychological sequelae of exposure to traumatic events among persons who had fought in or been the victims of war and violent conflict (13). Early terms that were used to describe the psychological symptoms observed after traumatic events included “nervous shock” (14), “shell shock” (15, 16), “traumatic neurosis” (17), and “rape-related fear and anxiety” (18). Because a number of studies published since 1980 have assessed disasters retrospectively, this review covers disasters occurring over a 40-year period. The earliest disaster included in our review is a 1963 landslide and flood that took place in northeastern Italy (19), and the most recent disaster included is the September 11, 2001, terrorist attacks in New York City (20–32). We identified the published literature using the MEDLINE, PsychINFO, and PILOTS databases, covering both US and international studies that assessed the epidemiology of PTSD after disasters. We also retrieved articles from key reviews (8, 33) that were not included in our own literature review. This review was not intended to cover the full range of consequences of disasters or the epidemiology of PTSD after individual traumatic experiences; we refer the reader to recently published comprehensive reviews of these topics (8, 33, 34). We limited ourselves to studies that either explicitly assessed PTSD as a disorder or used DSM criteria to assess post-traumatic stress symptoms; we did not include several other studies that assessed only psychological symptoms or other psychiatric disorders after disasters. Keywords and terms used for the search included primarily “post-traumatic stress disorder,” “PTSD,” “disaster,” “trauma,” and “mental health.” Classifying a traumatic event as a disaster is not always straightforward, and the distinction between individual traumatic experiences and disasters may be unclear. A substantial body of literature, particularly in the fields of sociology and hazard and risk management, has conceptualized disasters and their consequences (35). Much of this work has focused on disasters that are severely damaging and disruptive (36). Different definitions of disasters, at times conflicting, have been offered both by official agencies and by scientists in the field (37, 38). In reviewing the epidemiologic literature about mental health after disasters there are particular challenges that make the use of a single such definition limiting. For example, while commercial airplane crashes are nearly always considered disasters in the literature, personal airplane crashes (which may result in the death of several persons) seldom are. Similarly, although many disaster definitions are predicated, at least in part, on loss of life, some of the most important and best-documented disasters in the past 20 years (e.g., the Three Mile Island nuclear reactor accident (39)) did not involve loss of life. Therefore, for the purposes of this review, we deferred to the characterization of the event in the peer-reviewed literature and considered an event a disaster if it was considered a disaster by the authors of the papers reviewed. It has already been documented that human-made/technological disasters may have and consequences than natural disasters (8). we these two of disasters This to general from relatively comparable we about the and of A of that the epidemiology of PTSD after disasters were included in this among to disasters and to natural disasters. In studies of the epidemiology of PTSD after disasters, the be the definition and of the of PTSD the of PTSD prevalence and and the of and Disasters are traumatic events that involve persons and are by loss of and on a large there may be a wide range of people who may be considered of a who nearly who are of the and who a an epidemiologic this range of disaster both and of from one disaster to It is to this in postdisaster since disasters and to even when the disasters are For example, exposed to the in in have or the had a who in the or been in the of the In after a terrorist of a exposed persons include who were on the who were or the at the of the or the of victims In the of large disasters such as the September 11, 2001, terrorist attacks in New York it is that of a particular may be to the this a range of individual Therefore, in reviewing of be to the definition of the exposed PTSD was first as a in 1980, when it was included in the PTSD was as an and criteria for PTSD were criteria included a which that were and that only these events were of The of PTSD also the of one to the one to or to the and two symptoms to the of PTSD as a criteria for PTSD have been The criteria were in the Edition of the The A definition was relatively and the and criteria were from symptoms to A of PTSD the individual to have one and two In a of least was as The Edition of the DSM the definition of The definition to a traumatic and which is a of the the or at the A is than that in and a of that is For example, such events as the death of a potentially as events the (e.g., an death of a are explicitly Therefore, in studies that have assessed PTSD studies over the past it is important to in that definitions of PTSD may the documented and of on the a of criteria for in the and In although the of PTSD psychiatric is by a mental health the criteria in the many postdisaster studies make use of that have been to be for the of PTSD either by persons or by the of the PTSD and the for which are both there is consensus in the PTSD literature about the for The most commonly used in the PTSD research literature are the of and the Diagnostic the PTSD the National PTSD and the for PTSD have been from some of the and and are in PTSD Although a full of the of the use of is the of this review, we that and of and their in of PTSD have been documented In most disasters place over a of For example, a may a substantial in postdisaster studies may be particularly to of PTSD in their studies are to persons who had been for PTSD to that of is among persons Therefore, although some studies refer to PTSD in most this is considered to be PTSD prevalence at a given postdisaster we use the to postdisaster PTSD this review, in was among persons are two in of PTSD prevalence after disasters. in some not explicitly assess PTSD to the it be that even if persons had PTSD to a traumatic the PTSD documented is postdisaster this the that the of the disorder is the of traumatic event the postdisaster PTSD literature is assessing PTSD at any between a particular disaster and the of the are the first year after a disaster particularly in studies disaster victims have been assessed years and after the disaster Therefore, the prevalence of PTSD reported in most studies is as a a studies have documented PTSD PTSD prevalence in the or the which may not be comparable to the documented in other the peer-reviewed postdisaster literature is about both the of PTSD and the explicitly PTSD to the disaster Therefore, it is important to be when reported postdisaster PTSD of we not explicitly of of PTSD postdisaster for of the studies in our review, these the here. and comprehensive about papers reviewed to for The of studies that have assessed postdisaster PTSD have used study there is substantial in study Although is used to important of the range of and the used to assess significant between In are not in a substantial of published a need for when general about the of important of PTSD after disasters. 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For example, while to flood and exposure to flood were important of PTSD after the the of PTSD included fear of the of in which an airplane a of the a was an important of PTSD the of exposed to the City was the of PTSD of as assessed also an for and suggests that the of a exposure to a disaster is an important determinant of the of PTSD after a we the prevalence of PTSD after a disaster is among persons who were exposed to the disaster as among and in the general probably of exposure to disasters, victims the exposure and PTSD prevalence while persons in the general population have the of exposure and that have assessed after the disaster for For example, an of who were either or when a their in that the prevalence of PTSD among who were was as percent for A number of studies have assessed areas to and from a disaster that the prevalence of PTSD is higher among persons to the disaster than among that have been to be of PTSD after disasters include and have not been studied for to about their in other postdisaster studies have included of the of PTSD after human-made/technological disasters. In a study of who were a that in the prevalence of PTSD from percent in the first after the to percent after the This has been in studies of after an a and the among after the in which a terrorist over in on and in a study of the general population after the September terrorist attacks most studies that have assessed the of PTSD after disasters among victims that PTSD is for a years after the disaster among victims PTSD studies after the that percent of had PTSD years after the as percent at any in the years after the In a study of victims of the disaster in percent of persons who had PTSD in the first after the had PTSD years after the This of PTSD among victims of disasters has been in studies of persons exposed to the in persons by the City and of a in of these studies assessed the of PTSD over a of to the of PTSD a over and there is although two of the studies did not any of PTSD A recent study conducted after the September terrorist attacks that there were of PTSD as of PTSD although this has not been in studies for of the that be from studies of natural disasters was in the of or disasters. We the key about PTSD after natural disasters, between the epidemiology of PTSD after natural disasters and PTSD human-made/technological disasters. We refer the reader to for about individual the prevalence of PTSD documented in studies after natural disasters is than that documented in studies after human-made/technological disasters. in studies of natural disasters, it is to explicitly identify of persons who be considered research after natural disasters has been after events such as or in studies of human-made/technological disasters there is an of example, on an airplane that crashes is the in natural disasters such as which large among studies of PTSD after natural disasters, study include persons from a by the disaster This may include both persons who were exposed to the disaster personal exposure or the exposure of a and persons who were Therefore, the prevalence of documented PTSD in studies of PTSD after natural disasters as studies of PTSD after human-made/technological disasters is not studies after natural disasters a PTSD prevalence from percent to percent in the first years after a although most reported are in the of this range have been reported among and persons who were in areas by the disaster A number of studies of PTSD after natural disasters have studied PTSD among particularly the in a percent prevalence of PTSD was observed among the first years of A prevalence of post-traumatic was documented among after the in in Post-traumatic stress symptoms have been documented among after natural disasters in a number of the of percent of from a severely exposed and percent of from a exposed had of post-traumatic stress symptoms years after the the prevalence of symptoms among exposed is of from exposed to the in from after in and from after in A study after the in a 20 percent prevalence of PTSD among the first after the of PTSD after natural disasters are comparable to documented after human-made/technological disasters. include psychological such as and psychiatric are than men to have PTSD after natural disasters and is a higher of PTSD A of exposure to a disaster is the of PTSD to or after the and have been PTSD after natural disasters, in A studies have documented an between symptoms of PTSD and symptoms of PTSD among their and are PTSD after natural disasters. have been published peer-reviewed studies that have assessed the of PTSD after natural disasters. in a study of conducted after the percent of the were documented to have PTSD over a In to the studies of PTSD after human-made/technological disasters this study also documented of In a sample of studied after the in the prevalence of PTSD was to by one in the first years after the A study of of exposed to in that the prevalence of PTSD from percent to percent between and after the that while and symptoms over symptoms in PTSD was also documented between and after the in In this our goal was to a review of the evidence PTSD after disasters that a for research and there were in the of this review and particular of the literature in the field to some the here. we to a comprehensive review, a in the epidemiologic This to understand and from the body of work in the field that is to influence other and in a comprehensive review, we considered both studies that were and studies that may have included or may have been are two we not to our review to the evidence in the field is published in that and make it to systematically assess studies to epidemiologic given the of disasters, it is the that only one or two studies are conducted after a given by In several this work has been given the of the event and has Although we have that comprehensively review the body of work in the our in the has focused primarily on studies that were and that to the We in the to in a to to the of and the evidence for as we the criteria for PTSD over make In although disasters over the and are studied over the there are in the use of that were primarily and in primarily the United both and about that be from disasters, as in this review. A full of the criteria for PTSD have prevalence studies require of data studies at the a of studies have documented such Similarly, of in the it is to when used in a than the one for which were our review, intended for an epidemiologic focused on PTSD as a we did not other mental health consequences of disasters. goal was to the epidemiologic literature as it to one disorder that probably the most and debilitating of disasters. In using this we not to that other disorders not also important after disasters or that PTSD occurs in (8). psychiatric such as and have been documented after disasters, and there has been in the literature about the in only on PTSD as the of after disasters reviews to systematically assess the literature on other psychiatric after disasters, as as the literature on our review was limited by the epidemiologic literature and did not include important in PTSD epidemiology about which there is a of empirical For example, of the postdisaster to and in the may be as important in the of PTSD after disasters as the disasters the epidemiologic literature on these is limited, and as a of their in the of PTSD after disasters is not included here. of the postdisaster that the PTSD may be a particularly for conducted in the of disasters the past years have that there is a substantial of PTSD among persons who experience a In the published peer-reviewed literature is in that the of exposure to a disaster is probably the most important risk for the of Therefore, persons who are victims of a example, who are the a of PTSD than other In the prevalence of PTSD after disasters is among and in the general Although the prevalence of PTSD has been to be higher after human-made/technological disasters than after natural disasters, this to be to in studies conducted after human-made/technological disasters have focused on victims (e.g., persons who the in while a of studies has assessed PTSD in the general population (e.g., New after the September attacks studies of natural disasters include of people in the overall who were potentially by the disaster (e.g., of a an are to include both persons who are victims and in the general population who probably had exposure to the the is to of PTSD prevalence that be in the first year after disasters, exposure The empirical evidence suggests that the prevalence of PTSD among victims of disasters is the prevalence among is and the prevalence in the general population is by are and there are studies that the prevalence of PTSD is higher or than these for particular The of the disaster and the exposure to the disaster are probably the most important in the prevalence of some disasters are than and are by and to of PTSD have been reported among victims of disasters such as the and the had been in of the disaster and and In the documented prevalence of PTSD in the general population after the September 11, 2001, terrorist attacks in New York City was not higher than that in other studies of PTSD in the general population after disasters this probably the that while the September attacks US exposure to the disaster for most persons in the general New York City population was relatively In to exposure to an a number of risk for PTSD have been identified and to be important are to have a higher prevalence of PTSD after disasters than men or psychiatric and persons who have experienced traumatic events or substantial also have higher of has been to be a risk for PTSD in several studies Although there are a number of psychological that have been postdisaster there is one psychological the of that as particularly to postdisaster PTSD after psychiatric has been The of as a of postdisaster PTSD is research assess this using study In although the general and may after a for example, in and is a of research that has systematically assessed the of in postdisaster risk of The of a number of and in postdisaster PTSD risk unclear. The of PTSD after disaster has been studied in relatively it to general among victims of disasters have the of at least one of of PTSD for than years after disaster exposure some studies have the of PTSD in than one of than a after the disaster exposure studies evidence about the of PTSD after disasters Although there has been a that the of PTSD are from the of PTSD there is evidence this in the disaster is for additional studies to the of PTSD after disasters. body of reviewed evidence the prevalence of PTSD after disasters. We of that the prevalence of PTSD after a particular disaster may have important for of mental health and that of prevalence is the first in In there is a of research the of PTSD after disasters. In large part, this the that disasters are and population that may be used to assess PTSD in the event of a disaster is not population in the United States and in several the of PTSD these be to PTSD in the event of disaster exposure by some or of the Although some of PTSD are and for at after a there has been research to understand are at higher This is particularly important in the of such as We are of only one study that has to is a risk for PTSD after a disaster work assessing and for the observed between and PTSD be and for The of PTSD in the and after disasters This is to the in studies that have to of the of such research not be postdisaster PTSD may be of and it is that most PTSD after a disaster who is at risk for PTSD after disasters and PTSD such as or is More these PTSD and has for that may the psychological consequences of disasters, which may a than the of we there is a of evidence about the of the in the postdisaster in the of this may be a particularly important for of the of the postdisaster that may the of PTSD for to population mental health after disasters. This work was in by National of and The authors and for and for in papers in this review, and for on an of this