# Proinflammatory Markers in Prediction of Posttraumatic Psychological Symptoms: A Prospective Cohort Study

Authors: Alasdair George Sutherland; Gary A. Cameron; David A. Alexander; James D. Hutchison
Journal: Mediators of Inflammation
 (2008)

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## Abstract

Introduction. Posttraumatic psychopathology (PTP) describes the spectrum of conditions that can complicate the recovery from commonly occurring musculoskeletal trauma. There is a clear association with the activation of the hypothalamic-pituitary-adrenal axis (HPAA), and we wished to examine the predictive value of proinflammatory markers of the HPAA and of the GABA, which acts as an inhibitory regulator. Methods. Levels of proinflammatory markers and GABA were measured in 84 patients who had suffered musculoskeletal injuries requiring hospitalisation. PTP was assessed by the use of the General Health Questionnaire (GHQ) at presentation and again at two- and six-month reviews. Results. Significant psychological disturbance was noted in 39% of patients at two months and falling back to 18% by six months. There was no correlation between any of the markers tested at presentation and PTP at follow-up. Discussion. The HPAA response to trauma and the development of PTP are extremely complex. It is unlikely that a simple blood assay will provide significant predictive information, while incident specific information and patient perception are of more practical use.


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## Body

## 1. Introduction

Psychological disturbance after traumatic injury is common, and it is
now well recognised that disorders such as posttraumatic stress disorder (PTSD) are not confined to combat veterans or the survivors of major civil accidents [1–3].
There is a spectrum of posttraumatic problems; from short-lived adjustment
conditions such as acute stress disorder (ASD) to full PTSD, and a range of
comorbidities such as anxiety and depression can coexist with specific
posttraumatic symptoms. Rather than focusing upon only the most severe extreme,
we prefer to consider the full spectrum of posttraumatic psychological (PTP) symptoms
to describe the range of problems that may occur after a traumatic event [2].
We have previously demonstrated that 2 months after a musculoskeletal injury up
to 46% of patients have demonstrable psychopathology, falling to 22% by six
months [4]. This PTP is important to the treating trauma surgeon, as there is a
clear relationship between psychopathology and impaired functional recovery. Although it is not clear that primary
treatment of the psychological problems will necessarily yield an improvement
in recovery from the physical aspects of the injury [5, 6], it is certainly
clear that holistic care of the injured patient must include management of
their psychological state. The ability to predict which patients are at highest
risk of PTP, including PTSD, would allow scarce resources to be targeted at
those most in need.Previous work from our and other units has characterised aspects of
the injury, including injury severity and the patient's experience of the
accident, which are associated with increased risk of PTP [4, 7–9]. The
awareness of the centrality of the hypothalamic-pituitary-adrenal axis (HPAA)
to the development of PTP [10] has led to a search for biological markers that
might predict a tendency to develop PTP that is independent of the injury
itself. A recent paper has suggested that low levels of γ-amino butyric acid
(GABA) [11], an inhibitory modulator of the HPAA, may predict PTSD after road
traffic accidents. The proinflammatory
cytokines interleukin-6 and its soluble receptor (IL-6 and sIL-6r) and tumour necrosis
factor-α (TNF-α) have been identified as indicators of the
inflammatory response to physical stress and HPA disruption [12–17]. There is
some contradictory evidence for elevation of these cytokines in patients with
established PTSD [18–20] and posttraumatic psychopathology [21]. The relationship between psychiatric illness and
cytokine disturbance has been more widely studied, particularly with regard to
schizophrenia [22, 23], but it remains to be seen how this can be integrated in
the understanding of changes in PTP. GABA has an important
inhibitory role in the function of the HPAA  [24], and low levels have been
associated with increased risk of development of acute PTSD [11, 25].We wished to study
the relationship between GABA and a range of proinflammatory markers, which
also reflect HPAA function, and the development of PTP in our centre.


## 2. Materials and Methods

As part of a wider study of trauma outcomes, a
cohort of patients treated in the orthopaedic trauma unit of Aberdeen Royal
Infirmary were approached for recruitment. Patients eligible for entry were aged 17–70, with at least
one musculoskeletal injury. Head
injuries are known to affect psychological perception of injuries and so those
with significant head injuries (unconscious more than 15 minutes, Glasgow Coma
Scale less than 13) were excluded. Patients with fragility fractures were also
excluded. Patients were recruited within 48 hours of their injury, by means of
discussion, information sheet, and informed consent record. They were asked to complete the General health Questionnaire (GHQ) at
initial presentation, and gave an early morning sample of blood. Demographic
data related to their injuries
and backgrounds
were collected, including injury severity score (ISS) [26], the new injury
severity score (NISS) [27, 28], the revised trauma score (RTS) [29], and the
TRISS methodology score [30]. The study
had the full approval of the local research ethics committee.The GHQ is a validated and robust self-administered screening measure
to detect psychiatric disorders in community and nonpsychiatric clinical
settings [31, 32]. It is a 28-item questionnaire, producing a total score (a
higher score representing more severe psychiatric disturbance). The total score
further allows a threshold to be applied that defines “caseness”—the situation
where it is likely that clinical examination by a mental health specialist
would identify a genuine psychiatric condition. This does not define that the
patient has a specific psychiatric diagnosis (this would require a two-stage
approach), but it is a useful tool for identifying patients who would be so
defined. The threshold for this caseness definition is generally taken as a
score of 5 and above (out of  28) [31]. In a posttraumatic setting, there is
often extensive symptom overlap, and the GHQ allows us to identify those
patients with a psychiatric disturbance without narrowing the focus to one or
more specific diagnoses (e.g.,
PTSD).Blood was drawn between 0730 and 0830 for each patient, in order to
reduce the potential confounding effect of circadian rhythmns in production of
biomarkers under investigation. Sampling used a tourniquet and vacutainer
technique, taking 20 mL in two-clotting vacutainers. The clotted samples were
centrifuged at 2900 rpm for 15 minutes, and the serum carefully transferred to
nonsterile 5 mL vials (eppendorfs) using a microtitre pipette (Gilson). The
serum samples were stored at −40°C for no more than 24 hours before being
transferred to a −70°C freezer until required, when they were allowed to thaw
at room temperature. TNF-α, IL-6, and sIL-6r assays were carried out using
solid-phase enzyme-linked imunosorbant Assay assay (ELISA) kits (Quantikine,
R&D Systems Inc, Minneapolis, Minn, USA, distributed in the UK by
R&D Systems Europe, Abingdon, Oxon, UK). CRP assays
were carried out in the routine microbiology laboratories of Aberdeen Royal
Infirmary. Plasma GABA levels were determined using an LC-MS-MS chromatography method.Patients were followed up in line with standard clinical care for
their injuries. They were asked to repeat the GHQ at two- and six-month follow-up.Statistical analysis was undertaken on the Statistical Package for
Social Sciences (SPSS v 16.0, SPSS Inc, Chicago,
Ill, USA). Differences between GHQ caseness rates at
different follow-up times were analysed using the Wilcoxon signed-ranks
test. Normality of biomechanical data was tested using the Shapiro-Wilks test.
Relationships between biochemical markers, categorical demographic data, and
GHQ caseness were explored with the independent samplest-test, and
those between the individual biochemical markers and GHQ scores with Pearson
correlation testing. Logistic regression analysis was used to assess the
predictive value of the biochemical markers on GHQ caseness.


## 3. Results

During the course of the study, 84 patients were successfully
recruited to the metabolic markers group. Their mean age was 36 years (range 16–68 years), and
75% were men. Fifty percent were married
or cohabiting, while 45% were single, and 5% separated from partners. Alcohol
consumption was greater than 20 units per week in 14 (17%), while 35% were
smokers. Only one patient admitted the use of controlled substances, and eight
had previous psychiatric services contact.The mechanism of injury is summarised in Table1. The patients had
sustained a variety of musculoskeletal injuries, predominantly fractures, and
28 (35.5%) had multiple injuries. The modal ISS was nine (range 4–25), modal NISS
was also nine (range 4–41). The mode RTS was 7.84 (range 6.38–7.84), and the
modal TRISS survival probability was 99.40% (range 93.30–99.80%). Injuries
were managed surgically in 89% of cases. Follow-up for the group was 68 (81%) at two months and 62 (74%) at six
months.Table 1
Mechanism of injury (RTA = road traffic accident).
MechanismNo. patients (%)FallTotal29 (36)Low energy18 (22)From height11 (14)Work including machinery8 (10)RTATotal35 (41)Driver12 (14)Passenger7 (8)Motorcycle11 (13)Cyclist2 (2)Pedestrian3 (4)Sport11 (14)Assault1 (1)The mean GHQ score at initial presentation was 1.31 (out of 28),
rising at two months to 6.10, falling by six months to 3.39 (differences between
follow up and baseline levelsP<.001, Wilcoxon signed-ranks
test). The initial caseness level was
11%, rising to 39% at two months, and falling back partially to 18% by six
months (differences between follow-up and baseline P<.02, Wilcoxon
signed-ranks test).The mean standard deviation and the range for each of the biological
markers are shown in Table2. With the exception of GABA, each has a wide
range. The measured quantity of each of the biological variables was normally
distributed (Shapiro-Wilks test, P<.01). There were no correlations between levels of
biological markers and demographic data including age (by age bands), sex, and type
of injury (independent samples t-test, P>.05) and ISS score,
NISS score, TRISS, and RTS (Pearson's correlation, P>.05). There were no correlations between GABA level
and the levels of other biomarkers under investigation (IL-6, sIL6r, TNF-α, and
CRP) (Pearson's correlation, P>.05).Table 2
Biological markers levels.
Metabolic markersInitial(n=84)Mean (SD)RangeGABA (nmoL⋅L−1)0.55 (0.243)0.28–2.01CRP
(mg⋅L−1)44
(49.81)0–251.20IL-6 (pg⋅mL−1)83.75 (386.22)0–3393.08sIL-6r (pg⋅mL−1)36361 (8418)14587–66958TNF-α (pg⋅mL−1)27.37 (95.28)0–754.01The levels of GABA, IL-6, sIL6r, TNF-α, and CRP did not correlate
with GHQ total score at initial assessment and two- or six-month follow up
(Pearson's correlation, P>.05). Similarly, the mean levels were not significantly different between
cases and noncases (GHQ cut-off score five and above) (independent samples t-test, P>.05). Logistic regression analysis
revealed that none of the biochemical markers had any predictive value for GHQ
caseness (P>.10).


## 4. Discussion

The relationship between markers of HPAA function after
musculoskeletal injury and the risk of developing posttraumatic psychological
problems is complex, and we have not been able to identify a simple predictive
test from our data.Posttraumatic psychopathology is an important complication of
musculoskeletal trauma of the sort that presents every day to orthopaedic
trauma surgeons. It is associated with a significant delay in functional
recovery, and it is clear that genuinely holistic care of the injured patient
should include the psychological state. Psychological interventions for PTP,
including PTSD, are established, but are often limited in resource, and so
should be targeted at those most in need.We have previously reported on the relationship between psychological
and physiological state after trauma [4], but have focused on incident-specific
data in the prediction of at-risk status in our patients [9]. The recent
suggestion that GABA may be useful in PTSD prediction in the short term [11] prompted
our examination of GABA and proinflammatory markers of the metabolic response
to trauma and their relationship to subsequent development of PTP.Cortisol or ACTH assays are the most direct
measures of HPA function and have been used to predict PTSD symnptomatology [33],
but require complex methodology, particularly in specific timing of testing due
to the effects of complex circadian rhythmns. Function of HPA and proinflammatory markers of trauma are enmeshed and
complex, but it has been suggested that proinflammatory cytokine levels can
provide a physiological correlation with HPA function [17]. It is not possible
to identify a single marker of the inflammatory response to trauma. Each of the
three cytokines (IL-6, sIL-6r, and TNF-α) that we have tested as well as CRP have been
used in various studies of the response to physical trauma, including surgery [15, 34–48].A focus upon PTSD as the sole psychiatric consequence of trauma is,
in our view, too narrow. There is extensive symptom overlap in posttraumatic
conditions, and while some patients will exhibit frank PTSD, others may not
reach the diagnostic threshold while still suffering significant distress and
dysfunction in their everyday life. For this reason, we have preferred to
consider posttraumatic psychopathology (PTP) as representing the full spectrum
of pathological reactions to injury, including associated depression or anxiety.
This has led us to use GHQ as a screening tool for general psychiatric
symptomatology, rather than focussing on a single diagnosis; we believe that
this approach more truly reflects, in a practical way, the experience of our
patients rather than in a research-driven enquiry.Our data suggest no useful prediction of subsequent PTP by the
assessment of HPA axis function, as measured by GABA, CRP, and proinflammatory
cytokines. We have previously demonstrated the importance of the patient's
perception of the incident, and would suggest that it more strongly predicts PTP than a snapshot
of physiological markers [9].



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*Source: 640659-2008-12-22.xml*