Introduction
It has been almost four decades since cognitive processes were incorporated into psychological interventions of chronic pain, specifically through what is known as cognitive-behavioral therapy (1). The rationale is that these processes govern our interpretation of reality and, consequently, regulate our emotions and behavior. There are different levels of cognitive processing, depending on the degree of awareness at the moment they take place. One of the most successful at the time was automatic negative thoughts. These are subliminal, rapid and irrational cognitions that give a threatening or harmful meaning to how we experience events (2-4).
Almost thirty years ago, a more specific cognitive-behavioral model, the fear-avoidance model (5-7), put a spotlight on another type of cognitive variable, catastrophizing. It was defined by Albert Ellis in the 1960s as the tendency to magnify a threat and overestimate the seriousness of its potential consequences (8). Unlike automatic negative thoughts, catastrophizing could be considered a cognitive schema, error or bias, and as such, is more nuclear, unconscious and difficult to modify. The fear-avoidance model proposed the following explanation of the psychological imbalance that can be generated by pain: catastrophizing of a painful experience induces a fear of pain and also of movement, which in turn encourages the avoidance of situations and activities, which contributes to disability and depression, which increases the perception of pain, thus creating a vicious circle of chronification.
There is a great deal of evidence surrounding the components of the fear-avoidance model for the understanding and management of chronic pain. For example, a recent meta-analysis (k = 253; n = 42.463) found an average correlation of r = 0.28 [0.27-0.30 CI 95 %], that is, a moderate effect size between these components and pain intensity (9).
However, without a doubt, the most successful variable of the model has been catastrophizing. To confine ourselves just to its association with pain intensity, in a recent meta-analysis (k = 175; n = 13,628), the principal outcome of clinical trials on pain (10), was the report of associations of considerable effect sizes: moderate in knee pain (d = 0.54 [0.50-0.58 CI 95 %]); and minor to moderate in widespread pain (d = 0.40 [0.35-0.44 CI 95 %]) and in chronic lower back pain (d = 0.35 [0.30-0.40 CI 95 %]) (11). Catastrophizing influences the intensity of pain through supra-spinal mechanisms such as memory and attention, without altering spinal nociceptive mechanisms (12,13). What is more, catastrophizing has been found to be one of the main mediators of the effectiveness of different types of psychological treatments (14-16).
It is against this backdrop that a couple of decades ago the so-called third generation of cognitive-behavioral therapies emerged; in the field of pain, acceptance and commitment therapy is the foremost intervention (17). The third-generation models are fundamentally different from previous ones, not in terms of their cognitive content per se (for example, negative automatic thoughts), but due to their interest in how individuals relate to these thoughts, e.g., do they accept or reject them, minimize or catastrophize, embrace them or dissociate from them.
From this new perspective, an increased perception of pain is associated not as much with negative automatic thoughts themselves but with the relationship to them (e.g., catastrophizing). Therefore, the aim of this study is to test whether the association of negative automatic thoughts with a perceived intensity of pain is mediated by the level of catastrophizing experienced. Specifically, the hypothesis is that there will be a total mediation effect, that is, that increased catastrophizing scores will be the exclusive indicator of higher levels of negative automatic associated with higher levels of pain intensity.
Participants
This study is a re-analysis of data from an investigation into the influence of different sets of psychological variables on the experience of pain by patients with primary headaches and other chronic pain diagnoses (18).
Recruitment took place at three public centers in the province of Seville: two primary care facilities, the Torreblanca and Montequinto clinical management units; and the Pain Clinic of the University Hospital Virgen del Rocío.
At the primary care centers, the selection process took six months and was led by 16 out of 24 (67 %) physicians who opted to collaborate in the study. The selection criteria were as follows: a) a consult for headache; b) age 18 to 55; c) a diagnosis of migraine and/or tension headache, according to the International Headache Society (IHS) criteria; and d) not receiving any other treatment for headache beyond the usual pharmacological treatment (analgesics, anxiolytics, migraine drugs or antidepressants). The maximum age of 55 was established in order to minimize age-related comorbid complications. A total of 118 out of 156 patients (76 %) agreed to participate.
At the Pain Clinic, the invitation was opened to all patients who had attended treatment sessions for one week and who met the aforementioned inclusion criteria, with the exception of the required diagnosis, which, instead of headache, was chronic pain; furthermore, being in treatment at the clinic for pain was not a reason for exclusion. A total of 110 of 132 patients (80 %) agreed to participate. Of these, 25 % had not begun treatment; 32 % had attended between 1 and 5 treatment sessions; 25 % had attended between 6 and 10 sessions; and 28 % had attended more than 11 treatment sessions. Treatment was based on Traditional Chinese medicine, mainly acupuncture.
The study was approved by the ethics committees of the centers involved and participants signed an informed consent, in accordance with the Declaration of Helsinki (19).
All diagnoses were collected from medical records. These were, from highest to lowest frequency: migraine (n = 58), chronic tension headache (n = 50), fibromyalgia (n = 37), chronic lower back pain (n = 13), chronic neck pain (n = 10), rheumatoid arthritis (n = 8), osteoarthritis (n = 6), post-surgical pain (n = 5), ankylosing spondylitis (n = 4) and carpal tunnel (n = 3). The remaining diagnoses, with a frequency of one or two cases and accounting for 15 % of the total, were either more specific and distinct (e.g., shoulder pain, atypical facial pain, cluster headache, etc.); or non-specific and potentially classifiable in the above categories (e.g., osteoporosis, scoliosis, minor intervertebral degeneration, etc.).
The remaining socio-demographic and clinical information for the patients is presented in Table I.
Method
Design and variables
This reanalysis can be classified as a cross-sectional ex post-facto study. The resulting or dependent variable was pain intensity. The predictor or independent variables were those relating to negative automatic thoughts. The concrete factors that constituted the predictor variables are detailed in the materials section. The mediating variable was the catastrophizing of pain.
Materials and method
We shall only mention the material from the original study that is relevant to the present reanalysis. The full battery of tests was administered by a clinical psychologist in individual structured interview sessions lasting 1 to 1.5 hours.
The interview involved questions regarding the outcome variables. Pain intensity was measured using an eleven-point numerical scale, where 0 is no pain and 10 is the maximum pain imaginable. Pain frequency was measured in days per month (0 to 30) in which pain was experienced.
The following paragraphs describe all psychometric instruments used to measure the predictor variables, after they were subjected to the appropriate cross-cultural adaptations.
Three tests were used to measure negative thoughts: the Inventory of Negative Thoughts in Response to Pain (INTRP) (2), the Anxious Self-Statements Questionnaire (ASSQ) (4) and the Automatic Thoughts Questionnaire (ATQ) (3). Instead of running just one of these tests, all three were used in order to cover a wider spectrum of possibilities in terms of negative automatic thoughts related to the experience of pain.
The INTRP (2) is a 21-item psychometric test that is measured on a 5-point Likert scale, where responses to the question of whether you have negative thoughts when in pain range from a score of 0-Never to 4-Always. Our adaptation obtained five types of negative thoughts: general negative cognitions (“I’m useless”), 6 items, α = 0.85; negative social cognitions (“No one cares about my pain”), 4 items, 0.85; thoughts of disability (“Other people have to do things for me”), 6 items, α = 0.83; thoughts of lack of control (“I can’t control this pain”), 3 items, α = 0.66; and self-blame (“It’s my fault that it hurts”), 2 items, α = 0.78 (20).
The ASSQ (4) is a 32-item psychometric test that is measured on a 5-point Likert scale, where responses to the question of how often do you have certain thoughts when in pain range from a score of 1-Not at all to 5-Always. Our adaptation obtained four types of negative automatic thoughts: Intolerability (“I can’t take it anymore”), 12 items, α = 0.94; concerns about the future (“What am I going to do with my life?”), 8 items, α = 0.89; guilt and confusion (“I am completely confused”), 7 items,
α = 0.82; and doubts about self-efficacy (“Will I get through this?”), 5 items, α = 0.86 (21).
The ATQ (3) is a 30-item psychometric test that is measured on a 5-point Likert scale, where responses to the question of how often do you have certain thoughts when in pain range from a score of 1–Not at all to 5-All the time. Our adaptation obtained four types of automatic thoughts: Negative self-concept (“I’m a loser”), 9 items, α = 0.94; helplessness (“I’m so weak”), 11 items, α = 0.93; maladaptation (“What’s wrong with me?”), 4 items, α = 0.77; and self-blame (“I’ve let people down”), 6 items, α = 0.86 (21).
We used the Coping Strategies Questionnaire (CSQ) to measure the mediating variable, catastrophizing (22). In our adaptation, it is a 39-item psychometric test scored on a 7-point Likert scale, where in response to the question of how often do you think of the following when in pain range from a score of 0-Never to 6-Always. It consists of eight factors, among them, catastrophizing (“The pain is horrible and I think I’ll never get better”), 6 items, α = 0.89 (23).
Statistical Analysis
Data were statistically processed using the SPSS v26 programme (24). Means, standard deviations, frequencies and percentages were used to describe the study variables. Cronbach’s α coefficient was used to test the reliability of the psychometric scores, and Pearson’s r correlation was used to evaluate the association between them. To carry out the mediation analysis, once the assumptions of linearity, homoscedasticity, normality of estimation error and independence of observations were checked, we used the PROCESS macro for SPSS v3.5 (25) applying 10,000 bootstrap samples with an estimation of 95 % confidence intervals. Thirteen simple mediation analyses (Model 4) were conducted with catastrophizing as the mediating variable, pain intensity as the outcome variable, and with each of the thirteen types of negative automatic thoughts, consecutively, as predictor variables. These analyses estimated the direct effect of the predictor variable on the outcome variable, the total effect of the predictor and mediating variables jointly on the outcome variable and, finally, the most important result in this study, the indirect mediated effect, according to which the predictor variable would influence the outcome variable only through the effect of the mediating variable, which is confirmed when the confidence intervals of the indirect effect do not include 0. The level of statistical significance was set at p < 0.05.
Results
Table II presents the descriptive statistics of all study variables, predictors, mediators and criterion.
Before proceeding with the main analyses, we tested the possible association of the socio-demographic factors on our variables of interest, performing F-ANOVAs in the case of categorical measures, and Pearson’s r correlations in the case of quantitative measures. The results are presented in Table III.
The criterion variable, pain intensity, is not associated with any of them. The mediating variable, catastrophizing, is associated with a lower income per capita; it was higher for individuals with disabilities than those who were employed (+5.98) and for homemakers (+3.73); and lower for those with the highest level of education than for individuals with no schooling (-5.4) and those who had completed secondary education (-3.37).
Almost all predictor variables were associated with schooling: the higher the academic level, the lower the score of negative thoughts. Specifically, participants with a baccalaureate or university education scored lower than those who never attended school in general negative cognitions (-2.44), negative social cognitions (-3.9), thoughts of disability (-3.6), thoughts of lack of control (-2.44), intolerability (-8.3), concerns about the future (-5.99), guilt and confusion (-3.7), doubts about self-efficacy (-2.81), negative self-concept (-5.0), helplessness (-6.6) and maladaptation (-2.48). They also scored lower than participants with secondary education in negative social cognitions (-1.47), thoughts of lack of control (-1.5), concerns about the future (-2.54) and doubts about self-efficacy (-2.03).
Something very similar can be seen in terms of employment status: individuals unable to work experienced more negative thoughts. More specifically, compared with actively employed individuals, they scored higher in general negative cognitions (+3.6), thoughts of disability (+5.9), thoughts of lack of control (+2.7), intolerability (+6.31), concerns about the future (+6.66), doubts about self-efficacy (+2.2), helplessness (+5.88) and maladaptation (+2.03). Likewise, individuals with disabilities had higher scores than homemakers in negative social cognitions (+1.69), thoughts of lack of control (+1.49) and concerns about the future (+4.19).
In terms of marital status, single participants scored lower than married participants in negative social cognitions (-2.4), thoughts of disability (-2.59) and thoughts of lack of control (-1.98). Single participants also scored lower than participants with other marital statuses in thoughts of disability (-4.66), thoughts of lack of control (-3.08), concerns about the future (-9.35) and guilt and confusion (-4.93). Married participants also scored lower than participants with other marital statuses in self-blame (-2.79) and guilt and confusion (-3.34).
Gender only presented two significant associations: women scored 2.8 points higher in negative social cognitions and 2.05 points higher in self-blame. Finally, up to seven different variables correlated positively with age and number of treatment sessions, and negatively with income per capita (Table III).
Taking into account these results, covariates that showed statistically significant associations with predictors or mediators were included in each mediation analysis.
Mediation analysis
The scheme of the mediation analyses is presented in Figure 1. The different coefficients that are tested are: the effect a of each of the types of negative automatic thoughts (predictors) on catastrophizing (mediator); the effect b, catastrophizing on pain intensity (criterion); the direct effect c´ of each of the types of negative automatic thoughts on pain intensity; the indirect effect ab of each of the types of negative automatic thoughts on pain intensity through catastrophizing; and the sum of the direct and indirect effects, or total effect c.
The results of the mediation analyses are presented in Table 4. Controlling for the relevant socio-demographic variables, catastrophizing always had a statistically significant indirect effect p < 0.001; that is, it mediated the relationship between all types of negative automatic thoughts and pain intensity. The association always worked as follows: the more negative automatic thoughts, the more catastrophizing, and the more catastrophizing the more pain intensity perceived. These associations were only indirect, with the exception of thoughts of lack of control, which showed the only statistically significant direct effect p < 0.001, and constituted what is known as complementary mediation (26): the thoughts of lack of control over the pain are associated with an increase in the perceived intensity, both directly and through the catastrophizing effect. Taken one at a time and with catastrophizing as a mediating variable, the percentages of explained variance of the mediation models with negative automatic thoughts are considerably high and homogeneous, between 22 % and 26 %, indicating an estimate of at least one-fifth and up to one-quarter of the perceived pain intensity score.
Discussion
The aim of this study was to test whether the influence of negative automatic thoughts on pain intensity is mediated by the level of catastrophizing experienced. The results coincided with the general hypothesis that all associations between negative automatic thoughts and pain intensity would be positive, and that they would be mediated by catastrophizing. That is, only when negative automatic thoughts are associated with increased catastrophizing do they have an effect on perceived pain intensity. The role of catastrophizing in chronic pain has been well documented (11,27). Gellatly & Beck proposed the following cognitive model of catastrophizing (15): a precipitating event–in our case, pain–activates catastrophic beliefs, exaggerating the negative consequences of the event, generating an interpretative and attentional bias with a corresponding attentional fixation, and these processes encourage the emergence of negative automatic thoughts, intensifying pain which, in turn, empowers the catastrophic beliefs and thus closes the vicious circle.
The sole complementary mediation that was obtained deserves a special mention: thoughts of lack of control not only have an indirect effect on pain intensity through catastrophizing, they also have a direct effect. This finding is consistent with the evidence of the association of a perceived control over the intensity of pain; it moderates, for example, post-surgical pain (28), and even constitutes the core of the adaptive or maladaptive profile of patients. With regard to the latter, chronic pain patients who believe their pain is not dependent on anything or is by pure chance present higher levels of intensity, interference and disability (29). While it is true that we have tested many different types of negative thoughts, it is logical that only the thoughts of lack of control have a direct influence on the intensity of pain, as unpredictability and lack of perceived control are well-established factors in the experience of chronic pain (30).
With respect to the association of negative automatic thoughts and catastrophizing in perceived pain intensity, our results align with the existing evidence of this increase, with small to moderate effect sizes (11,13,31).
Additionally, this study has highlighted that those who are less educated or disabled are particularly vulnerable to automatic negative thoughts and the catastrophizing of pain. As there is still very little evidence on these variables as moderators of the association between catastrophizing and pain, further study is recommended (32).
There were several limitations to this investigation. The first had to do with the cross-sectional design, which only allowed for a glimpse of the relationships between the study variables, but not in a dynamic way, much less to verify causal hypotheses. The second limitation stemmed from the characteristics of the sample and setting, neither of which was randomized, thus resulting in a lack of representativeness owed to: the prevalence of certain diagnoses and the level of psychological adjustment of the patients to chronic pain. Another limit was the inability to strictly control some of the exclusion criteria, such as the presence of co-morbid psychopathology. Finally, the decision to set a maximum age of 55 as part of the participation criteria limits the sample representativeness of the adult population that suffers from chronic pain.
There are two main implications of our results. First, they show the role of catastrophizing as a mediator of pain perception, which contributes to the justification of the presence of this variable as a target for pain interventions, and not just psychological ones (14). Second, they also contribute to theoretical evidence on the psychological processes involved in chronification. In particular, the fact that automatic thoughts are not directly associated with pain intensity supports the rationale that rather than the mere presence or frequency of automatic thoughts, it is the way in which the patient relates to these thoughts–in this study, whether or not the patient catastrophizes–that triggers their harmful effect. This is something that had already been advocated in the Rational Emotive Behavior Therapy (REBT) approach, which understood catastrophizing as a transdiagnostic mechanism for different problems, and which focused on deep irrational beliefs rather than superficial automatic thoughts (33). More recently, the process of identifying with absolute literalness what is thought with what is real, known as cognitive fusion(34), is one of the six key components of the psychological flexibility model and one of the psychological treatments it inspired, Acceptance and Commitment Therapy (ACT) (17).
Finally, we must remember that the role of catastrophizing in a painful experience is not limited to mediation, but has also been explored as a predictor and moderator of therapeutic efficacy (35,36), and there is still a long way to go in this respect.
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