Anxiety is often but not always associated with the incidence of chronic postsurgical pain (CPSP) [1]. Munafo and Stevenson examine the effect of anxiety trait and anxiety state on the incidence of chronic pain after different surgical procedures. They only included the studies that had used the State–Trait Anxiety Inventory in order to address the inherent variability in the measurement tool. The results of their meta-analysis showed that anxiety trait (the tendency to perceive an objectively non-dangerous situation as threatening and to respond to it with disproportionate fear responses) was associated with the occurrence of CPSP in 4 out of 7 studies. On the other hand, anxiety state (an unpleasant emotional reaction accompanying the stress of surgery) was more commonly associated with the occurrence of chronic pain. In fact nine out of the 11 studies showed a correlation between anxiety state and the occurrence of CPSP. Munafo and Stevenson [1] consider that self-assessment causes a response bias that reflects the persistence of anxious behaviour. The nature of the mechanisms underlying the association between preoperative anxiety and postoperative recovery is therefore different from what has been suggested by other studies.

Hinrichs-Rocker et al. [2] carried out a review of studies published between 1996 and July 2006, with the aim of identifying factors that predict and correlate with CPSP. They included 50 studies, selected according to two criteria: (1) the level of evidence (ability of the study to answer the question), and (2) the quality of the association between the predictive factor or correlate and the CPSP. Only two studies [3, 4] scored the maximum number of points for both of the criteria set out above. In the first study, the patients with high preoperative anxiety had the highest pain scores 1 year after implantation of a total knee prosthesis. In the second, use of psychotropic drugs was higher in patients with pain assessed between 6 and 10 months after cholecystectomy.

The most commonly cited study is the one by Tasmuth et al. [5], whose main aim was to assess the effects of CPSP following treatment for breast cancer on the remembered intensity of acute postoperative pain in breast surgery. Depression was assessed using two questions and only a small number of patients were involved, so the results of this study must be interpreted with caution. More severe preoperative depression was seen in those patients who developed chronic pain 1 year after surgery, and the depression only improved in those patients who did not have pain. In another study carried out by the same author [6], the somatic dimension of the Beck Depression Inventory, which is associated with hospitals carrying out few operations, increased the risk of CPSP 1 year after breast surgery (whether the hospital carries out few or many operations is defined on the basis of the number of operations carried out annually).

Poleshuck et al. [7] considered depression as a risk factor for both the occurrence and the intensity of chronic pain after breast surgery. The measurement tools were self-reported scales (Beck Depression Inventory) and clinician-assessed scales (Hamilton Depression Rating Scale). This dual assessment was clearly useful because it included individuals in the analysis who were unaware that they were depressed or who had a tendency to minimise their condition. In this study, depression did not increase the risk of developing chronic pain, regardless of its intensity. In the case of total knee replacements [3], the intensity of CPSP was high in patients whose preoperative depression was severe. Conversely, in the study carried out by Harden et al. [8], depression did not predict the occurrence of complex regional pain syndromes at 3 and 6 months.

From these various studies it cannot be concluded with any certainty that anxiety or even depression may be a causative factor for CPSP. What is more, anxious or depressed states are seen during the postoperative period, when the pain increases or persists over time, when intercurrent life events make the individual more vulnerable (financial problems) or when postoperative complications occur.

The term neuroticism is used to describe individuals who are predisposed to negative emotions (anxiety, anger, depression). This personality trait has been studied by Danish teams in patients undergoing cholecystectomy [9, 10], and more recently in patients receiving a total prosthetic hip replacement surgery [11]. The results of these studies are contradictory. Preoperative neuroticism does not predict the occurrence of chronic pain in the study by Bisgaard et al. [10], while the two older studies [9, 12] showed that neuroticism was associated with the occurrence of CPSP. For Jess et al. [12], neuroticism was not a cause but a consequence of chronic postsurgical pain. The number of patients with pain and scoring highly for neuroticism had increased 1 year after the operation.

The concept of neuroticism introduces the idea of anxiety, which is strongly correlated with CPSP. Anxiety may therefore exacerbate neuroticism and induce a relationship between it and CPSP [13].

Cognition refers to mental processes (thoughts, beliefs and interpretations) that accompany and lend meaning to the painful experience as it is experienced or observed. After a surgical procedure a patient often hopes that a pre-existing pain will improve rapidly, and this may not occur. Any increase in the pain or persistence of pain gives rise to incorrect and sometimes catastrophic interpretations that do not reflect the patient’s real somatic state.

Catastrophising [14] is a personality trait which is relatively stable over time but it is also a cognitive response that can be modified through targeted therapeutic interventions. It refers to individuals who have a tendency: (1) to focus on the painful sensations (rumination); (2) to exaggerate the threatening aspect of the pain (amplification); (3) to see themselves as unable to control the painful symptoms (helplessness). In the study by Jensen et al. [15], high-intensity catastrophising, assessed 1 month after amputation, is associated with increased phantom limb pain, disability and symptoms of depression. Contrary to all expectations, catastrophising is also associated with a reduction in functional disability and depression occurring between 1 and 6 months postoperatively. The authors offer two explanations to account for these unexpected results: (1) the individuals with high levels of catastrophising have a greater “margin” to make progress; (2) they mobilise the attention of those around them more effectively and therefore obtain the help and support that they need at a very early stage after the amputation. Hanley et al. [16] reproduced the study by Jensen et al. and confirmed their results, with a longer period of follow-up (24 months after amputation). Catastrophising is associated with a reduction in symptoms of depression at 1 year and a reduction in functional disability and symptoms of depression 2 years after amputation. In knee arthroscopy [17], the total score on the catastrophising assessment questionnaire (Pain Catastrophizing Scale: PCS-T) and the “rumination” sub-score (PCS-R) allow patients with pain to be distinguished from those without pain according to the pain rating index used in the Mac Gill questionnaire (Pain Rating Index), and patients who had persistent pain at 24 months also had the highest preoperative scores for PCS-T and PCS-R.

Catastrophising, whatever its repercussions, is therefore a cognitive factor that must be taken into account in future studies. These should allow us to gain a better understanding of its mechanisms of action, either alone or in interaction with other factors.

Surgery often gives rise to erroneous cognitions because its outcome is uncertain a priori. Individuals who represent the surgery and its consequences in negative terms are at a higher risk than others of developing chronic pain [18, 19]. In an initial study [18], fear of surgery (incomplete recovery, failure of the operation, unwanted effects of surgery, long rehabilitation period) is associated with chronic pain at 6 months, regardless of the nature of the operation. In a second study [19], it was the expectation of negative consequences in relation to postoperative recovery that increased the incidence of chronic pain 6 months after lumbar discectomy.