INTRODUCTION

The goals of psychiatric and psychological assessment of the chronic pain patient (CPP) are:¹ (1) diagnosis of psychiatric pathology, (2) prediction of behavior, (3) decision-making for treatment planning, (4) prediction of response to treatment, and (5) evaluation of change of symptoms (outcome). Of these goals, the most important is that of decision-making for treatment planning. This goal, however, cannot be accomplished without a clear delineation of the current psychiatric and psychological problems of the CPP. It is unfortunate that the above goals do not lend themselves readily to the formulation of a problem list out of which a problemoriented psychiatric and psychological treatment plan can be readily developed. The usual chapter on the psychiatric and psychological evaluation of the CPP ignores this issue. Generally, a generic global approach to the evaluation of the CPP is touted and presented rather than the problem-oriented approach. It is therefore the goal of this chapter to present a problem-oriented approach to the psychiatric and psychological evaluation of the CPP, utilizing the concept of ‘comorbidity.’ In addition, as there is very little information on the psychiatric and psychological evaluation of the patient with acute or subacute pain, these areas will not be addressed in this chapter. Finally, some chapters on the psychiatric and psychological evaluation of the CPP include the evaluation of pain and function. As these two topics are huge in scope, they will not be addressed in this chapter.

PSYCHIATRIC, PSYCHOLOGICAL, AND SOMATIC COMORBIDITIES ASSOCIATED WITH CHRONIC PAIN

A ‘comorbidity’ has been defined as any distinct clinical entity that exists or occurs during the clinical course or treatment of the index disease.² In this case, the index disease is chronic pain. Treatment of the index disease can be complicated by the comorbid disease or condition, which can interfere with or increase the difficulty of treatment, resulting in worse prognosis for the index disease.³ Thus, ‘comorbidity’ can lead to spurious medical outcomes and false research information in reference to the index disease. Comorbidity is a psychiatric concept because it has been noted for years that psychiatric illnesses are comorbidly associated with each other.³ However, it is only recently that the ‘comorbidity’ concept was applied to CPPs.^4–10 Thirty years of research and clinical experience have crystallized into a body of knowledge, which can, with relative certainty, delineate which ‘comorbidities’ are found in the ‘usual’ chronic pain patient (CPP). This issue is important because it then simplifies the psychiatric and psychological examination of the CPP. Screening questions can be asked for the comorbidities usually found and/or specific tests can be given to measure these comorbidities. Application of the comorbidities concept also facilitates a ‘problem-focused’ approach to the treatment of the CPP.

Three major groups of comorbidities are usually associated with chronic pain (CP): (1) psychiatric problems meeting the threshold for diagnosis utilizing the Psychiatric Diagnosis And Statistical Manual of Mental Disorders, 4th edition (DSM-IV);¹¹ (2) psychological problems which may not meet the threshold for diagnosis according to the DSM-IV, or which are not diagnosable by the DSM-IV system, e.g. conflicts over abuse (sexual or physical), etc.; and (3) somatic comorbidities, which may or not have a behavioral component.

CPPs usually demonstrate significant psychiatric comorbidity. In an early study, Fishbain et al.¹² reported that in a large group of CPPs treated at a pain facility, only 5.2% had no DSM-III (the system used at that time) diagnosis on Axis I where state diagnoses, such as anxiety and depression, are coded. Thirty-four point nine percent had one diagnosis, but 59.9% had more than one diagnosis on Axis I.¹² Thus, overall, 94.8% had psychiatric comorbidity, while approximately 60% had complex comorbidity (more than one diagnosis). The most common/frequent comorbidities usually found in CPPs are presented in Table 9.1 in order of decreasing frequency.

Table 9.1 Psychiatric Comorbidities on Axis I of the DSM-IV Usually Found in CPPs in Order of Frequency^{4,5,7,10,12–15}

Psychological comorbidities are also frequently associated with chronic pain (CP). These behavioral comorbidities develop because of the environmental response of the patient developing CP and are situation dependent. For example, the usual CPP finds himself/herself with what he/she perceives as a medical problem for which physicians cannot make an appropriate diagnosis and/or develop a cure.¹⁶ Meanwhile, this illness is associated with significant disability, which has tremendous impact on the CPP’s life, yet physicians are not able to assign an appropriate impairment which matches the disability.¹⁷ The CPP is often suspected or accused of having a drug problem, or faking,^18,19 or having a psychiatric problem in order to try to assign an explanation for the mismatch between the observed medical impairment and the disability.^9,20 As a result, the CPP gets into conflict with the insurance and medical systems and winds up in litigation. The litigation process is extremely stressful, often leading to economic uncertainty for the CPP until settlement. All of these diverse environmental problems can increase stress, and in fragile individuals leads to psychiatric comorbidity. The psychological comorbidities usually found in CPPs are presented in Table 9.2. This table is subdivided into 12 major areas which will be discussed below.

Table 9.2 Psychological Comorbidities Usually Found in CPPs^4,21–29

The somatic comorbidities usually found in CPPs are presented in Table 9.3. Studies of fatigue, headache, sleep, and memory/concentration problems indicate that these comorbidities are extremely common within CPPs.^4,30 Because the group of comorbidities usually present as symptoms and signs which interfere with function, the presence of any of these increases the difficulty in rehabilitating the CPP.³⁰ Some of the comorbidities fall under the rubric of medically unexplained symptoms. As such, they become the purview of the psychiatrist or psychologist. Because these comorbidities are usually not evaluated by the psychiatrist or psychologist, they are only presented here for the sake of completeness.

Table 9.3 Somatic Comorbidities Usually Found in CPPs^{4,8,30–39,40,41}

The comorbidities presented in Tables 9.1 and 9.2 will be utilized below in a problem-oriented fashion to suggest an approach to the psychiatric and psychological evaluation of the CPP. This in turn lends itself to the algorithmic approach.

PAPER AND PENCIL TESTS TO BE UTILIZED TO COMPLEMENT THE PSYCHIATRIC OR PSYCHOLOGICAL PAIN INTERVIEW

SCREENING QUESTIONS AND MEASUREMENT APPROACHES FOR THE PSYCHIATRIC COMORBIDITIES

Table 9.5 presents a series of screening questions for the psychiatric comorbidities frequently found in CPPs. In addition, this table presents what are currently thought to be the most useful paper/pencil tests for these comorbidities. The paper and pencil tests can be administered if the CPP answers affirmatively to the screening question. As an alternate approach, the pain clinician can request a psychiatric or psychological consultation if the screening questions are answered in the affirmative. Some of the suggested tests in Table 9.5 deserve comment (below). Characteristics of these tests in reference to chronic pain will be found in Table 9.6.

The Beck depression inventory (BDI) is a 21-item, self-report questionnaire relating to depression.^46,47 It was developed for psychiatric patients, but has been utilized and written about extensively in reference to CPPs. As it is a rating scale, it is an excellent tool to measure improvement. Unfortunately, because of its focus on somatic symptoms (fatigue, sleep, concentration), which are frequently found in CPPs (Table 9.3), it will overestimate the severity of depression. As an example, the cutoff score for being depressed in physically healthy individuals is 10. A recent study exploring the predictive validity of the Beck in CPPs found the optimal cutoff score to be 21.⁴⁸ However, the BDI does have a significant proportion of items for cognitive symptoms of depression versus other depression rating scales.⁴⁹ As such, it does not give greater weight to somatic symptoms versus other rating scales. Its use is therefore recommended.

The Beck scale for suicide ideation^46,47 is designed to measure current suicidal ideation. It is a 21-item scale which has been shown to have significant correlation with the BDI. However, it has been shown not to have predictive validity for suicide completion. It was developed and tested in psychiatric patients and has not had wide use in CPPs. However, it may have some utility in CPPs who voice suicidal ideation, and as it is a rating scale, it can be utilized to measure improvement in suicidal ideation.

The State–Trait^46,47 anxiety inventory is a 40-item self report rating that differentiates between State anxiety, a temporary condition experienced by some individuals, and Trait anxiety, the general chronic anxiety experienced by some individuals. Thus, it evaluates how likely an individual is to feel anxiety (Trait), and how anxious the individual feels at the moment (State). It has good correlation with other widely used anxiety scales. However, it has not been utilized widely in CPPs. As such, its reliability and validity here have not been determined.

Recent reviews have concluded that the prevalence of post-traumatic stress disorder in CPPs has been underestimated.⁵⁰ Although there are a number of tools available that are developed around the DSM-IV criteria for this diagnosis, none of these is specific to the CPP. The Post-traumatic Chronic Pain Test⁵¹ has been specifically developed for use in CPPs and as such is recommended.

CPPs may suffer from subclinical obsessive-compulsive disorders. This has now been termed obsessive-compulsive spectrum disorder (OCSD).⁵² A number of psychiatric disorders, such as body dysmorphic disorder, anorexia nervosa, binge eating, hypochondriasis, sexual compulsions, pyromania, kleptomania, trichotillomania, compulsive buying, pathological gambling, and some self-injurious behaviors appear to demonstrate some obsessive traits and are therefore included in OCSD disorders. The OCSD patients utilize the types of mechanisms and behaviors often noted in obsessive-compulsive disorder (OCD). As such, these mechanisms and behaviors make the index disorder, e.g., gambling, worse and more difficult to treat. At issue, then, is whether these types of mechanism operate in some somatizing disorder such as pain disorder. The features of OCSD and OCD overlap in many respects, including demographics, repetitive intrusive thoughts or behaviors, comorbidity, and etiology. Most importantly, it appears that this group of disorders responds preferentially to antiobsessional drugs, such as clomipramine and the selective serotonin reuptake inhibitors (SSRIs), e.g. fluvoxamine.^52,53 There have been no treatment studies utilizing the OCSD concept for pain disorders. However, a number of cases have been published.⁵³ The author has reported¹⁵ on the positive response to antiobsessional agents in three cases of chronic atypical facial pain. Recently, there has also been a report of positive response in two patients with schizophrenia and chronic pain to clomipramine.⁴⁰ This limited evidence indicates that perhaps CPPs with ‘non-specific’ pain and prominent obsessive-compulsive components should be treated with an SSRI at the first opportunity. Thus, it becomes important to identify CPPs who may have prominent OCD traits. As such, the use of the Padau Inventory for OCD is recommended.^46,47 However, it is to be noted that this inventory has not been utilized in CPPs.

One of the screening questions for psychoactive substance use disorder requires comment. There is currently significant evidence that smokers are at greater risk than nonsmokers for developing psychoactive substance use disorders. This relationship may also hold for CPPs. As such, smoking is including as a screening question.

Multiple somatic symptoms are allegedly found frequently in CPPs. These raise the suspicion of somatization. Historically, somatization has been measured by the MMPI or the SCL-90. However, researchers have argued that these instruments are sensitive to current somatization rather than longstanding somatization traits.⁵⁴ As such, the Pain Patient Profile⁵⁵ test is recommended. This inventory measures somatization and has been normed on CPPs.

SCREENING QUESTIONS AND MEASUREMENT APPROACHES FOR THE PSYCHOLOGICAL COMORBIDITIES

Screening questions and suggested tests for the psychological comorbidities are presented in Table 9.7. Some of these comorbidities and measurement approaches require comment (below).

As noted above, CPPs are subjected to a number of significant stressors. These stressors in some predisposed CPPs lead to the development of severe anger.^56,57 Greater levels of anger were shown to be associated with poorer treatment outcome from a pain management program.⁵⁸ To measure this concept the State–Trait Anger Expression Inventory^46,47 is recommended. This inventory is not pain specific, but has been utilized in CPPs. Another anger inventory is the battery for Health Improvement.⁵⁹ This is an inventory that contains a doctor dissatisfaction scale, which makes it unique. In addition, it has been standardized on patients in rehabilitation, with a significant percentage of those experiencing chronic pain. Its use, especially to measure doctor dissatisfaction, is therefore recommended.

Chronic pain rehabilitation programs emphasize return to work. However, recent pain research has demonstrated that pre-injury job stress is predictive for return to work post pain facility treatment.²⁷ As such, the measurement of pre-injury job stress can identify perceptions about work, which can have an impact on rehabilitation and can thus become the target of occupational rehabilitation. For this purpose, the Occupational Stress Inventory⁶⁰ is recommended. This inventory has satisfactory reliability and validity in CPPs. Another scale that may be useful in such instances is the BH12⁵⁹ as it has a job dissatisfaction scale. This scale assesses angry feelings directed toward the workplace. These feelings are further broken down into negative attitudes towards the company, supervision, coworkers, and the job itself. This scale has established validity and reliability with patients in physical rehabilitation.

Significant others around the CPP can respond in one of three ways to the CPP’s pain behaviors: in a supportive fashion; rejecting fashion; and oversolicitous fashion. Psychological theory holds that oversolicitousness can reinforce pain behavior. On the other hand, the rejecting spouse can lead to stress. The West Haven–Yale Multidimensional Pain Inventory^61,62 has a solicitousness scale and also taps the rejecting concept. It has been developed for CPPs. As such, it is recommended to measure these concepts.

For a number of years a series of research reports have suggested that there is a greater proportion of victims of sexual abuse in CPP populations than in the general population. A recent review of this literature has, however, concluded that the evidence does not demonstrate a causal relationship between childhood abuse and chronic pain.⁴¹ However, the pain clinician may wish to investigate this issue. Two screening questions are suggested for this problem (see Table 9.7) and no questionnaire is recommended. The second screening question, ‘Have you ever, etc.,’ has been shown to have significant reliability as a self-report measure⁶³ and is therefore recommended after the initial open-ended question. If the clinician wishes to investigate this issue further, the BH12⁵⁹ has a Survivor of Violence scale. This scale assesses a history of physical and sexual abuse, occurring both in childhood and adulthood. The scale was also normed on chronic pain patients.

Coping can be defined as a purposeful effort to manage or mitigate the negative impact of stress.⁶⁴ The pain literature has been concerned with problem-focused coping strategies to manage pain where coping has been seen as either active or passive.⁶⁵ Active coping strategies are attempts by the CPP to obtain some control over the pain by using his/her resources, e.g. using relaxation techniques, etc.⁶⁵ Passive coping strategies, on the other hand, indicate a reliance on external agents for pain control, e.g. medications, etc.⁶⁵ The Copies Strategies Questionnaire²³ was developed on CPPs and contains the catastrophizing scale. This scale has been shown to predict poor treatment outcome if elevated.⁶⁶ As such, this scale is recommended to measure this concept.

Pain beliefs is another important concept in the pain literature as it relates to how the pain is viewed. Pain beliefs appear to be important because fear/avoidance beliefs have been shown to predict functional disability.⁶⁷ Patient confidence (self-efficacy) in handling pain can be assessed via the Arthritis Self-efficacy Scale.⁶⁸ In addition, CPPs may be anxious about their pain and fear it. These concepts can be evaluated via the Pain Anxiety Symptom Scale²⁵ and the Tampa Scale for Kinesophobia.²⁶ Data obtained through these inventories can identify target behaviors, which can then become the focus of intervention.

The final issue relates to the assessment of personality in CPPs. Historically, in CPPs this has been done utilizing the MMPI or the SCL-90. Although there are numerous studies attempting to predict pain facility treatment outcome with these personality assessment tools, the research is equivocal. To date, it is unclear whether these tools can serve this purpose, with the majority of researchers claiming that they cannot. In addition, as pointed out above,⁴⁴ there are major problems with these tools in reference to State–Trait issues. As such, the use of these inventories in CPPs is to be discouraged.

CONCLUSIONS

This chapter has attempted to outline an algorithmic approach to the psychiatric and psychological evaluation of the CPP based on the concept of comorbidity. In the future, it is likely that pain clinicians will be better able to define and understand the comorbidities found in CPPs. This approach will allow the identification and further evaluation of comorbidities and their treatment. Such understanding will facilitate the development of more successful treatment approaches for the chronic pain patient.