The limitations inherent in the small sample and the attrition precluded precise inferences. Nevertheless, given the dearth of published long-term studies on psychological consequences for children involved in major traffic accidents, the findings could contribute to further research. The initial load on psychological resources was apparently high. After four years, some psychological reactions had decreased in the indirectly affected group, and further continued up to 20 years after the incident. At this point, the now adult participants who were directly affected reported mild posttraumatic stress, and indirectly affected participants endorsed almost no posttraumatic stress reactions. No difference in general mental health or in complicated grief was observed between the groups. Complicated grief and posttraumatic stress reactions were correlated after 20 years, and mostly participants who were directly affected experienced the event still affected their daily lives.
In the first survey after 9 months, there was a substantial proportion who reported sadness and avoidance reactions in both the directly and indirectly affected groups, and the directly affected had more feelings of guilt and nightmares. Intrusion is considered a hallmark symptom of PTSD, and although no assessment was made as to whether the children suffered from PTSD, the 9% prevalence of nightmares in the indirectly affected group paralleled the 9-month 6% prevalence of PTSD found in indirectly affected schoolchildren after a bus-train collision in Israel . In the present study, 8% of the children stated they would like to meet a professional to talk about their feelings about the accident.
After 4 years, about half of the indirectly affected participants reported no upsetting thoughts during about the bus crash the past year; however, the remainder felt that they would like to meet a professional to talk about the event. In a 7-year follow-up after an Israeli bus and train collision , 12-17% of the then 20-years old conscripts who had been both directly and indirectly exposed had sought military mental health services, compared with 1% of children from a nearby school. These findings substantiate help-seeking behaviour is also expected to increase in indirectly affected for several years after a large RTA. In this study, only changes in sadness and avoidance were determined between 9 months and 4 years, whereas and there were only small or no changes for intrusions and nightmares, and feeling guilt or fear when thinking of the bus crash. Therefore, the findings herein were similar to clinical observations after a mudslide engulfed a primary school : during the first four years, the most common symptoms reported by the children to their general physician were sleeping difficulties, nervousness, avoidance, instability and enuresis.
After 20 years, the directly affected group reported some chronic posttraumatic stress reactions, and these were still markedly higher than the indirectly affected who reported minimal chronic reactions. In the indirectly affected group, intrusions appeared more long-standing than avoidance and hyperarousal reactions. In a 33-year follow-up of children affected by a mudslide , significant posttraumatic stress remained in a quarter of the sample, whereas, the rates of other psychopathological disorders were not elevated. However, it can only be speculated as to whether the higher symptom load after the mudslide disaster, compared with the results presented here, is due to a ubiquitous threat of another mudslide imposed on those children, or the result of successful acute support interventions after the bus crash . Posttraumatic stress reactions, but not general psychopathology, can be prolonged into adulthood in children and adolescents who have been exposed to single traumatic events [16, 18, 38], which was supported by the results of this study. Negative life events, other than the bus crash, were positively associated with decreased general mental health but not with posttraumatic stress after 20 years.
Measures of posttraumatic stress in bereaved trauma samples victims may be confounded by prolonged grief reactions , and traumatic bereavement is associated with worse long-term outcome in both children  and adults . In this study, grief and posttraumatic stress were closely intertwined, and further studies could disentangle the long-term consequences of traumatic stress and traumatic bereavement.
This study suffered from several limitations. First, the sample size was small, especially for the directly affected group, as only 11 children survived the bus crash. The inherent difficulties would have been reduced if the response rate for the indirectly affected group had been higher: only 33 responded out of 91 individuals traced from this group. This introduced possible response bias, i.e., the respondents were a biased sample of all indirectly affected eligible participants. It has been suggested those least affected are less inclined to respond . Thus, a response bias would have attenuated the differences between the indirectly and directly affected groups. Second, as only aggregate data were retained from the first two surveys, a comparison of respondents and non-respondents in the indirectly affected group based on previous assessment of PTSS was precluded. Further, in consideration of the age of the participants and the setting in which the study was conducted only single items were chosen in the first two surveys for identifying affective and anxiety reactions, These items were derived from a reliable and valid questionnaire [17, 22], however, as the items have not been empirically tested, the validity and reliability is uncertain, although face validity may not have been compromised.
Although the assessment of treatment effects was beyond the scope of this study, the results suggested participants who had received treatment since the event had more posttraumatic stress reactions and worse general mental health than those who had not received treatment. This corresponded to previous findings [35, 42], and might be due to direct involvement predisposing individuals towards seeking professional help , or that those who seek treatment have a higher acute symptom load. As such, the results implied that receiving treatment was not as a result of improved subsequent mental health, but as an effect of worse prior mental health. That treated subjects report worse mental health needs addressing in further studies.