Dolor crónico musculoesquelético y trastorno de estrés postraumático: el papel psicológico de la vulnerabilidad y la protección/musculoskeletal chronic pain and posttraumatic stres disorder: the role of psychological vulnerability and protection
- Autores: Gema Teresa Ruiz Párraga
- Directores de la Tesis: Alicia Eva López Martínez (dir. tes.)
- Lectura: En la Universidad de Málaga ( España ) en 2012
- Idioma: español
- Tribunal Calificador de la Tesis: Rosa Esteve Zarazaga (presid.), Carmen Ramírez Maestre (secret.), Elbert Geuze (voc.), Sofía López Roig (voc.), Pedro Javier Amor Andrés (voc.)
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- Resumen
Chronic pain is a major health problem in Western countries, leading to enormous economic and social burdens in Europe and the United States. A recent study (Langley et al., 2011) demonstrated a prevalence of around 17.25% in the adult population, with chronic back pain being the most common problem (60.53%).
Pain is understood as a multidimensional phenomenon, i.e., dependent on biological, psychological and social factors. Many multidimensional models of chronic pain have been formulated, some of which have been mentioned in Chapter 1. Thus, the fear-avoidance model (Vlaeyen and Linton, 2000) is one the most important models due to its importance and relevance in explaining pain-associated disability, highlighting the role of variables such as anxiety sensitivity, catastrophizing, fear of pain, hypervigilance and avoidance in this process. Another relevant model is the diathesis-stress model of chronic pain (Dworkin and Banks, 1999) that attempts to explain the pathogenesis and maintenance of chronic pain. According to this model, individual differences in the predisposition to develop chronic pain problems are primarily due to different degrees of vulnerability. Thus, a previous history of traumatic events is considered a psychosocial factor of vulnerability to chronic pain.
Many studies have provided evidence of an association between exposure to different kinds of traumatic events and the presence of a chronic pain syndrome (Ang et al., 2006; Balousek, Planem and Fleming, 2007; Brown, Berenson and Cohen, 2005; Casey et al., 2008; Coker et al., 2000; Gironda et al., 2006; Goldberg and Golstein, 2000; Kindler, Jones, Perrin and Bennet, 2010; Jones et al., 2009, 2011; Kang et al., 2000; Linton, 2002; Peterlin et al., 2007; Rivara et al., 2008; Sachs-Ericsson et al., 2007; Sansone, 2006; Walsh, et al., 2007). However, the relationship between trauma exposure and chronic pain is complex; some authors have suggested that a traumatic event in itself would not have an affect on chronic pain (Ciccone et al., 2005; Clum et al., 2000; Lang et al., 2006; Shipherd et al., 2009; Wolfe et al., 1994; Zoellner et al., 2000).
One potential mechanism that could explain this complex relationship is the presence of posttraumatic stress disorder (PTSD). The association between PTSD and chronic pain syndromes is supported by empirical evidence (Otis et al., 2003; Sareen et al., 2007; Shipherd et al., 2007), and some authors have suggested that the association between a history of trauma and a diagnosis of chronic pain is mediated, at least partially, by the development of PTSD (Ciccone et al., 2005; Clum et al., 2000; Lang et al., 2006; Shipherd et al., 2009; Wolfe et al., 1994; Zoellner et al., 2000). Thus, PTSD has been identified as a major risk factor for chronic pain (Jenewein et al., 2009a; Martin et al., 2010; Miró et al., 2008). Moreover, psychological theory suggests that several psychological variables, such as anxiety sensitivity, experiential avoidance, catastrophizing, fear-avoidance beliefs, fear of pain and pain hypervigilance, play a major role in the increased response to pain among PTSD patients (Asmundson et al., 2002; Asmundson and Hadjistavropolous, 2006; Liedl and Knaevelsrud, 2008; McLean et al., 2005; Otis, Keane and Kerns, 2003; Sharp and Harvey, 2001). Martin et al. (2010) investigated the role of PTSD symptoms using the diathesis-stress model; their findings offer preliminary support not only for the potential role of PTSD symptoms in this model, but also for the fear-avoidance model of chronic pain (Asmundson et al., 2004; Norton and Asmundson, 2003; Vlaeyen and Linton, 2000).
Resilience has been proposed as a positive factor that protects individuals from PTSD (Atkinson et al., 2009; Fincham et al., 2009; Paton, 2006; Solomon et al., 2007), apparently moderating the association between PTSD risk factors and the development of PTSD by buffering the effects of the risk factors (Bensimon, 2012; Fincham et al., 2009; McFarlane et al., 2009). Studies on resilience and chronic pain support the protective role of resilience in adjustment to chronic pain conditions (Hanssen et al., 2009; Karoly and Ruehlman, 2006; López-Martínez et al., 2009; Ramirez-Maestre et al., 2011; Strand et al., 2006; Zautra et al., 2005; Wright et al., 2008).
In contrast to experiential avoidance, pain acceptance has been shown to play a protective role in the pain experience. Several studies have found that pain acceptance is associated with lower pain intensity, improved daily functioning, and better mood (McCracken, 1998; McCracken, Vowles and Eccleston, 2004; Wright et al., 2011). Pain acceptance is also negatively associated with higher avoidance levels and pain-related disability (McCracken and Samuel, 2007).
Despite the co-occurrence of PTSD and chronic pain, and the relevance of the aforementioned psychological variables in both disorders, few studies have examined these variables in trauma-exposed chronic pain patients with and without PTSD symptoms. However, studies clarifying the vulnerability and protective variables and mechanisms associated with PTSD and chronic pain are needed, not only because of the high co-morbidity associated with both disorders, but also because of the need to design therapeutic protocols and programs adapted to the different profiles of chronic pain patients.
FIRST STUDY Differences in vulnerability and protective psychological variables between non-trauma-exposed, trauma-exposed without posttraumatic stress disorder, and trauma-exposed with posttraumatic stress disorder chronic musculoskeletal pain patients OBJETIVES AND HYPOTHESIS The first aim of this study was to examine differences in pain vulnerability (AS, EA, catastrophizing, fear-avoidance beliefs, fear of pain, and pain hypervigilance) and protective (resilience and pain acceptance) psychological variables between non-trauma-exposed, trauma-exposed without PTSD and trauma-exposed with PTSD chronic musculoskeletal pain patients. Based on this aim, we hypothesized that trauma-exposed patients with PTSD would show significantly higher scores than trauma-exposed patients without PTSD and non-trauma-exposed patients on vulnerability psychological variables and lower scores on protective psychological variables. We also hypothesised that no differences would be found between non-trauma-exposed patients and trauma-exposed patients without PTSD in any of the vulnerability and protective psychological variables considered.
The second aim of this study was to examine differences in pain-adjustment variables between non-trauma-exposed, trauma-exposed without PTSD and trauma-exposed with PTSD chronic musculoskeletal pain patients. Thus, the following hypotheses were tested: a) trauma-exposed patients with PTSD would show significantly higher scores than trauma-exposed patients without PTSD and non-trauma-exposed patients on those variables reflecting less adjustment to pain (pain intensity, pain-related disability, and emotional distress); and b) no differences would be found between non-trauma-exposed patients and trauma-exposed patients without PTSD in any of the pain-adjustment variables considered.
METHODS Participants A total of 714 patients with chronic musculoskeletal back pain (cervical, thoracic, lumbar, and sacral) of benign origin were assessed. They were all referred by physicians and physiotherapists from several Primary Care Health Centres in Málaga (Spain).
Various criteria were applied to select the three groups of patients (non-trauma exposed, trauma-exposed without PTSD, and trauma-exposed with PTSD), such as exposure to a traumatic event, timing of exposure to trauma, traumatic events scores, and presence of PTSD symptoms. A total of 346 patients were divided into three groups: 110 trauma-exposed patients with PTSD symptoms (TE with PTSD), 119 trauma-exposed patients without PTSD symptoms (TE without PTSD), and 117 non-trauma-exposed patients (NTE).
Measures The following questionnaires were used: - Stressful Life Event Screening Questionnaire Revised (SLESQ-R; Green et al., 2006).
- Davidson Trauma Scale (DTS; Davidson, 1996).
- Anxiety Sensitivity Index (ASI; Reiss, Peterson, Gursky, and McNally, 1986).
- Acceptance and Action Questionnaire (AAQ; Hayes et al., 2004).
- Pain Catastrophizing Scale (PCS; Sullivan, Bishop and Pivik, 1995).
- Fear-Avoidance Beliefs Questionnaire (FABQ; Waddell, Newton, Henderson, Somerville and Main, 1993).
- Pain Anxiety Symptoms Scale (Short Form) (PASS-20; McCracken and Dhingra, 2002).
- Pain Vigilance and Awareness Questionnaire (PVAQ; McCracken, 1997).
- Resilience Scale (RS; Wagnild and Young, 1993).
- Chronic Pain Acceptance Questionnaire (McCracken, Vowles and Eccleston, 2004).
- Numerical Rating Scale of Composed Index of Pain (Jensen, Turner, Romano and Fisher, 1999).
- Roland Morris Disability Questionnaire (RMDQ; Roland and Morris, 1983).
- Hospital Anxiety and Depression Scale (HADS; Zigmond and Snaith, 1983).
Procedure The patients who met the inclusion criteria were referred by their physicians. The selected participants were contacted by telephone and invited to participate in the study. The participants who accepted completed a battery of questionnaires in the same order in an oral semi-structured interview format. Informed consent was obtained prior to data collection. Patients were aware that the information collected was confidential.
RESULTS Differences in vulnerability and protective psychological variables A stepdown analysis was performed to examine the relative importance of anxiety sensitivity, experiential avoidance, fear-avoidance beliefs, fear of pain, pain hypervigilance, resilience and pain acceptance in differentiating the three groups of patients (NTE, TE without PTSD, and TE with PTSD). The preliminary analyses showed that there were significant differences between the groups in these variables, and thus several ANCOVAs were conducted in which the number of medical visits, number of psychological sessions, number of pills taken daily and number of trauma exposure events were used as covariates.
The results of the ANCOVAs showed that there were significant differences between the groups in all the psychological vulnerability variables associated with pain adjustment (anxiety sensitivity, experiential avoidance, catastrophizing, fear-avoidance beliefs, fear of pain and pain hypervigilance). Furthermore, significant differences between groups were found in the protective psychological variables associated with adjustment to pain considered in the study: resilience and pain acceptance.
Post hoc comparisons with Bonferroni corrections showed that there were statistically significant differences between the TE with PTSD patients and the other two groups of patients (NTE and TE without PTSD) in all the psychological vulnerability variables considered in the analysis; specifically, the TE with PTSD group had higher means in anxiety sensitivity, experiential avoidance, catastrophizing, fear-avoidance beliefs, fear of pain, and pain hypervigilance. In addition, there were no statistically significant differences between the NTE and TE without PTSD groups in any of these variables. There were also statistically significant differences between the TE with PTSD patients and the other two groups of patients (NTE and TE without PTSD) in the psychological protective variables considered in the analysis; specifically, the TE with PTSD group had lower means in the resilience and pain acceptance variables than the other two groups of patients. On the other hand, there were no statistically significant differences between these two groups in any of these variables.
Differences in adjustment to pain The results of the ANCOVAs showed that there were significant differences between the groups in all the pain adjustment variables considered in the analysis. Post hoc comparisons with Bonferroni corrections showed that there were statistically significant differences between the TE with PTSD patients and the other two groups of patients (NTE and TE without PTSD) in all the pain adjustment variables. Specifically, the TE with PTSD group had higher means in pain intensity, pain-related disability and emotional distress, whereas the NTE and TE without PTSD groups did not significantly differ in any of these variables.
CONCLUSIONS As far as we know, this is the first study that has simultaneously compared several relevant variables involved in these two disorders ¿ PTSD and chronic pain¿ in a large clinical sample that included men and women. Although there is a vast literature on pain and traumatic events, as well as on pain and PTSD disorders, the results of this study indicate that the variables associated with adjustment to pain differ depending on the type of patients referred (trauma-exposed without PTSD symptoms vs trauma-exposed with PTSD symptoms). Therefore, distinguishing between trauma exposure and PTSD after trauma is clearly relevant. In addition, a broad range of stressful situations experienced by the patient over their lifetime was evaluated, since the literature shows the importance of conducting studies in which not only one type of traumatic experience is taken into account, but the entire spectrum of life adversities which a person has been exposed to (Finkerhor et al., 2007; Sachs-Ericsson et al., 2009). Furthermore, the current study controlled for potentially confounding variables that are known to differentiate PTSD patients from those pain patients without symptoms of this disorder The findings of this study support the postulates of different models of PTSD and chronic pain and the results emerging in this area of study. Moreover, the findings indicate that having been exposed to traumatic events is not a sufficient condition to develop PTSD or poor adjustment to chronic pain. It is probable that other variables, such as resilience, are involved in mediating these associations. Therefore, the mechanisms of vulnerability and protection associated with PTSD and chronic pain should be identified to deepen our understanding, such that new therapeutic protocols and programs can be designed that are adapted to the different profiles of chronic pain patients.
SECOND STUDY A comprehensive model of adjustment to pain in the co-occurrence of PTSD and chronic musculoskeletal pain: vulnerability and protective pathways after traumatic events OBJECTIVE AND HYPOTHESIS This aim of this study was to examine the association between trauma, resilience, PTSD, and the variables included in the fear-avoidance models in explaining adjustment to chronic pain. Based on the literature, it was hypothesized that: a) resilience would be negatively associated with PTSD and positively associated with pain acceptance; b) anxiety sensitivity (AS) would be positively associated with PTSD, experiential avoidance (EA), fear-avoidance related to pain (catastrophizing, fear-avoidance beliefs, fear of pain, pain hypervigilance), and adjustment to chronic pain (pain intensity, pain-related disability and emotional distress); c) PTSD would be positively associated with fear-avoidance related to pain (F-A) and adjustment to pain; d) pain acceptance would be negatively associated with AS, F-A and adjustment to chronic pain; e) EA would be positively associated with adjustment to chronic pain; f) F-A would be positively associated with adjustment to chronic pain; and g) adjustment to chronic pain would depend on the levels of AS, PTSD, F-A, EA and pain acceptance.
Thus, it was proposed that the two pathways, vulnerability and protection, would be interconnected.
METHOD Participants The sample consisted of 229 chronic musculoskeletal back pain patients who had been exposed to a traumatic event before the onset of pain. This sample was formed by combining two of the groups of chronic pain patients included in Study 1: trauma-exposed with PTSD symptoms (TE with PTSD, n = 110), and trauma-exposed without PTSD symptoms (TE without PTSD, n = 119).
The measures and procedure used were the same as in the previous study. As these have already been described, they have been omitted to avoid over-burdening the reader.
RESULTS Evaluation of a comprehensive model of adjustment to pain in the co-occurrence of PTSD and chronic musculoskeletal pain: vulnerability and protection pathways after traumatic events Structural Equation Modelling (SEM) with maximum likelihood estimation was used. Statistical tests indicated that the hypothesized model adequately fitted the data (RMSEA = .07; CFI = .99; NNFI = .98; TLI = .96). The ¿2 test was significant (¿2 (8) = 19.25, ¿2 /dl = 2.40, p = .014). As ratios of 3 or less indicate an acceptable fit of the model (Kline, 2005), the results provided support for the hypothesized model. All the standardized path coefficients were significant (p < .05).
CONCLUSIONS This study provides empirical support for the potential role of PTSD symptoms in fear-avoidance models of chronic pain, and may provide support for the diathesis-stress model of pain. It is the first comprehensive model of adjustment to pain to consider vulnerability and protective adaptation mechanisms in patients who have undergone a traumatic event. The study highlights the importance of a comprehensive framework of reference to understand the comorbidity of PTSD and chronic musculoskeletal pain, and the need to provide well-designed treatment programs for the simultaneous treatment of these conditions.
