There are strong associations between substance misuse and psychological trauma. According to one US study, 3% of substance misusers in the general population have post-traumatic stress disorder (PTSD). ^{Reference Cottler, Compton, Mager, Spitznagel and Janca1} Rates of PTSD in female substance misusers on in-patient units rise to 42.5% ^{Reference Dansky, Saladin, Brady, Kilpatrick and Resnick2} and to 62% for pregnant women treated in a residential setting. ^{Reference Thompson and Kingree3} In the UK, rates of PTSD on in-patient substance misuse units have been reported at 38.5% for current PTSD and at 51.9% for lifetime PTSD. ^{Reference Reynolds, Mezey, Chapman, Wheeler, Drummond and Baldacchino4} Surveys of adolescent substance misusers report PTSD rates of up to 19.2%. ^{Reference Deykin and Buka5}

In civilian populations without PTSD, rates of lifetime substance misuse range from 8.1 to 24.7%, but in those with PTSD the levels rise to 21.6-43.0%. ^{Reference Kessler, Sonnega, Bromet, Hughes and Nelson6-Reference Breslau, Davis, Peterson and Schultz8} Up to 75% of US and UK war veterans with PTSD meet the criteria for alcohol misuse or dependence. ^{Reference Kulka, Schlenger, Fairbank, Hough, Jordan and Marmar9,Reference Fletcher10}

Individuals with comorbid substance misuse and PTSD are more likely to have other psychiatric diagnoses, higher rates of psychosocial and physical problems, higher rates of in-patient admissions for substance misuse and higher rates of relapse compared with substance misusers without PTSD. ^{Reference Breslau, Davis, Peterson and Schultz8,Reference Najavits, Gastfriend, Barber, Reif, Muenz and Blaine11}

Within the general population, estimates of childhood sexual abuse in women are around 21-22% and in men 7-15%. ^{Reference Kelly, Regan and Burton12,Reference López, Carpintero, Hernàndez, Martín and Fuertes13} However, childhood sexual abuse levels among substance misusers on in-patient detoxification units range from 49 to 67% for women and 12-33% for men. ^{Reference Windle, Windle, Scheidt and Miller14-Reference Stone16}

The association between substance misuse and psychological trauma is therefore important, not only because of the frequency of comorbidity and the additional complexity of the presentation, but also because of the more complicated clinical course and poorer prognosis.

This paper presents the results of a survey of 104 individuals with alcohol or opiate dependence who were undergoing a detoxification at New House Drug and Alcohol Unit, Shrewsbury, Shropshire. The survey sought to identify the number of individuals who were currently affected by symptoms of psychological trauma, to assess the severity of any psychological trauma using the Impact of Events Scale (IES), ^{Reference Horowitz, Wilner and Alvarez17,Reference Sundin and Horowitz18} and to identify and describe the sorts of events that patients considered to be responsible for the development of their psychological trauma symptoms. Implications for the management of these individuals are discussed in the light of research findings and the National Institute for Health and Clinical Excellence (NICE) guidelines for the management of PTSD. ¹⁹

Method

All individuals who participated in this survey had given informed consent. A total of 104 in-patients with alcohol or opiate dependence undergoing detoxification were assessed for current symptoms of psychological trauma using the Impact of Events Scale (IES). This instrument was administered when patients were no longer experiencing any acute symptoms of alcohol or opiate detoxification. The IES grades the severity of 15 characteristic symptoms of psychological trauma that have been experienced in the 7 days before testing. Eight items of avoidance behaviour and seven items related to intrusive memories are measured. The maximum score is 75. Scores over 25 are considered to indicate a level of disorder that requires treatment. The severity of symptoms were rated as subclinical (scores between 0 and 8), mild (9-25), moderate (26-43) and severe (scores over 43) in accordance with the guidelines of Corneil et al ^{Reference Corniel, Beaton, Murphy, Johnson and Pike20} (E. Hutchings, personal communication, 2004). The IES also records the date and nature of the event considered responsible for the symptoms of psychological trauma.

We used the χ²-test for statistical analysis of proportions and the t-test for differences between means.

Results

The prevalence and severity of symptoms of psychological trauma according to type of dependence and gender are summarised in Table 1.

Table 1. Mean IES scores and prevalence data by severity^a

				Gender
IES trauma score	Alcohol dependence n = 73	Opiate dependence n = 26	Dual dependence n = 5	Male n = 74	Female n = 30
Mean IES scores	29.7	19.0	29.4	25.6	30.4
IES scores 0–8 (subclinical)	16	12	1	21	8
IES scores 9–25 (mild)	11	3	1	12	3
IES scores 26–43 (moderate)	26	8	1	26	9
IES scores 44–75 (severe)	20	3	2	15	10

Overall, 75/104 patients had symptoms of psychological trauma: 60 patients had symptoms in the treatable range (IES>25) and 25 scored in the severe range (IES>43).

The number of traumatised patients with alcohol dependence (57/73) was significantly higher than the proportion of traumatised patients with opiate dependence (14/26; χ² = 5.552, P = 0.018). Similarly, the mean IES score of patients with alcohol dependence was significantly higher than that of patients with opiate dependence (t = 2.367, P = 0.019). There were too few patients with dual dependence to draw any conclusions.

There were no significant differences between the IES scores of males and females. However, only 15/74 (20%) male patients scored in the severe range on the IES compared with 10/30 (33%) females, suggesting that there is a non-significant trend for females to experience severe symptoms of psychological trauma compared with males (χ² = 1.995, P =0.16).

Data showing the types of events considered responsible for symptoms of psychological trauma in 75 affected patients are summarised in Table 2.

Table 2. Life events and traumatic events that patients associated with psychological trauma

Event	Symptomatic patients, n
Life event
Death (e.g. loss of parents/siblings/children)	23
Divorce or separation (e.g. voluntary or enforced separation from wife/husband/children)	15
Adult abuse (e.g. bullying at work, bullying within family, emotional abuse by partner, domestic violence)	4
Traumatic event
Child abuse (e.g. childhood abuse (physical/sexual/emotional) perpetrated by parent or other family member)	19
Violent assault (e.g. held hostage, road traffic accident, industrial accident, rape, surgical complications)	9
Saw trauma (e.g. witnessed man shot in head, found hanging body, army service in Korea, saw boyfriend murdered, saw suicide of father)	5

‘Life events’ were responsible for symptoms in 56% of individuals. The mean IES score for life events was very close to that for ‘traumatic events’ (36.8 and 37.9 respectively).

Traumatic events occurred in 44% of the affected group. A significantly greater proportion of females in this group experienced severe symptoms (IES>43; n =7/22 females, n =5/53 males; χ² =5.796, P =0.02) and were significantly more likely to report childhood abuse (n = 10/22 females, n =9/53 males; χ² =6.663, P =0.01).

Discussion

The prevalence of symptoms of psychological trauma in patients on a detoxification unit was surprisingly high. The results of this survey suggest that over half of the patients interviewed (58%) had symptoms in the range requiring treatment and almost a quarter (24%) had IES scores that were severe. It is not possible to make a diagnosis of PTSD from an IES score. However, these findings support the US and UK data. ^{Reference Dansky, Saladin, Brady, Kilpatrick and Resnick2,Reference Reynolds, Mezey, Chapman, Wheeler, Drummond and Baldacchino4}

Patients with alcohol dependence were significantly more likely than patients with opiate dependence to report symptoms of psychological trauma and their greater severity. This may be due to the fact that the in-patient unit only admits people with complex, severe alcohol dependence, whereas, in contrast, access for opiate users is enhanced in order to meet current treatment targets. Life events were associated with symptoms in more individuals than traumatic events and, unexpectedly in our view, resulted in IES scores of equal severity. In this sample, the nature of the event itself appears to give little indication of the traumatising effect it may have. Life events would not be regarded within ICD-10 or DSM-IV as sufficiently extreme or catastrophic to induce PTSD. However, our observation is similar to that of Mol et al ^{Reference Mol, Arntz, Metsemakers, Dinant, Vilters-van Montfort and Knottnerus21} and highlights a potential diagnostic anomaly in which all the symptoms of psychological trauma or PTSD may be present, but the nature of the traumatic incident eliminates a diagnosis. This inconsistency may be addressed in DSM-V. ^{Reference Rosen, Spitzer and McHugh22} A greater proportion of female patients reported IES scores in the severe range resulting from a traumatic event, and they were also more likely to report childhood abuse than male patients. These findings are consistent with those from previous studies. ^{Reference Reynolds, Mezey, Chapman, Wheeler, Drummond and Baldacchino4,Reference Najavits, Gastfriend, Barber, Reif, Muenz and Blaine11,Reference Stone16,Reference Triffleman, Marmar, Delucchi and Ronfeldt23}

This survey demonstrates the value of routinely assessing substance misusers for symptoms of psychological trauma. Clinical and epidemiological studies confirm that comorbidity between PTSD and substance use disorders is common and that such patients tend to be more severely affected and more refractory to treatment than those having either disorder alone. ^{Reference Najavits, Gastfriend, Barber, Reif, Muenz and Blaine11,Reference Ouimette, Brown and Najavits24}

Conclusions

The common and complex relationship between substance misuse and psychological trauma demonstrates the pressing need to screen for, and treat, both conditions. Despite the frequency with which individuals with comorbid disorder present for treatment, no systematic treatment approach of proven efficacy has been developed for this vulnerable patient group in the UK. Comorbid substance dependence and psychological trauma receives considerable attention in research, but very little emphasis in routine clinical practice.

Declaration of interest

None.