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