Personality assessment and the minnesota multiphasic personality inventory in chronic pain

Commentary

Personality Assessment and the Minnesota Multiphasic Personality Inventory in Chronic Pain Underdeveloped and Overexposed Dennis C. Turk* and Ephrem Fernandezt

ince its publication over 50 years ago, the Minnesota Multiphasic Personality Inventory (MMPI)6 has attained almost a mythic status in psychology. It has become the prototypic instrument to use in evaluating personality characteristics and specific traits of individuals, even though it originally was developed specifically for the assessment of psychopathology. The MMPI has been widely adopted for use in assessing pain patients prior to treatment and to predict outcomes of treatments as diverse as surgery, chemonucleolysis, and multidisciplinary pain management. In their provocative Focus article, Main and Spanswick suggest that the MMPI, as well as the construct of personality, needs to be reevaluated in light of available research. It is Main and Spanswick's central thesis that the MMPI is conceptually outdated and seriously flawed. They imply that the continued reliance on the MMPI is an example of superstitious behavior, where the continued use of this instrument is more a result of habit than careful consideration of its appropriateness, structural and functional adequacy, or clinical utility. Moreover, they challenge the importance of personality itself, in the experience of pain, implying that personality reinforces a mind-body dualism and suggesting that personality is largely unrelated to the experience of pain and subsequent disability. After over a half century of use and the publication of the revised version of the MMPI (MMPI-2),2 Main and Spanswick's article serves as a useful stimulus for

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reconsideration of this instrument and the logic of personality assessment in chronic pain. The MMPI, as any assessment instrument, can be evaluated regarding the traditional psychometric issues of reliability, validity, and clinical utility, along with those of the methods of standardization and norms available for comparative purposes. The reliability, validity, factorial instability (independent factor analytic studies uncovering anywhere between 6 and 21 factors), item-scoring redundancy (in the MMPI-2, there are 654 items scored on the clinical and validity scales, but only 398 unique items, many of which load on more than one scale, thus increasing the risk of confounding among diagnoses), and unrepresentativeness of the standardization sample in both the MMPI and MMPI-2 (the original standardization relied primarily on people living in Minnesota, whereas the second edition included a normative sample somewhat broader in geographic representation, but with a higher than average socioeconomic status) have been carefully dissected in recent papers by Helmes and Helmes and Hedden." These critiques detail major reservations about the MMPI, as noted by Main and Spanswick. Thus, we will not review the psychometric issues here, but encourage the reader to examine these recent analyses carefully. Rather, we will consider several issues raised by Main and Spanswick, namely, functional limitations of the MMPI, role of dispositional factors in the experience of pain, and language and pain.

FUNCTIONAL LIMITATIONS From 'the University of Pittsburgh School of Medicine. Pittsburgh, PA and tSouthern Methodist University, Dallas, TX. Reprint requests: Dennis C. Turk, PhD. Pain Evaluation and Treatment Institute. University of Pittsburgh School of Medicine, 4601 Baum Boulevard, Pittsburgh. PA 15213.

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Although Main and Spanswick have recapitulated the structural and conceptual problems of the MMPI as discussed in reviews by Helmes? and Helmes and Redden.' we see a need to emphasize further the func-

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tional limitations of the MMPI (with particular reference to chronic pain). Psychometrics aside, the important question is "of what clinical utility are MMPI scale score elevations and profiles?" As Main and Spanswick point out, MMPI profiles and numerical codes are really abstractions unlike radiographs of the body. Yet, there is a danger of reification of these constructs into concrete and completely stable representations of the patient's psychological makeup . Desp ite their descriptive value, MMPI profiles face important interpretive problems. Helmes and Hedden " point out that higher scores on the MMPI do not imply greater pathology in the respondent, but a greater likelihood that the individual is characterized by the psychological features measured by that scale. In other words , a patient with a standardized or t-score of 80 on scale 6 does not necessarily have greater paranoid ideat ion than one with a t-score of 60 on the same scale . Strictly speaking , the only inference one can make is a probabilistic one expressing greater confidence about the existence of paranoia in the former than the latter individual. Minnesota Multiphas ic Personality Inventory data obtained from pain patients may also be of questionable value because of the lack of face validity of many of the test items for pain patients. The predominance of items that appear unrelated to pain (or much of anything of importance for that matter) may give pain patients the impress ion that the ir physical symptoms are of relatively little significance to the health care provider or that the provider believes that "the pain is all in their head." Since, in the absence of sufficient objective physical findings to support the reported symptoms, patients are often given the implicit if not explicit message questioning the veracity of their report, it would not be surprising if they become resistant, if not hostile . Such a view by a patient is likely to impair the therapeutic alliance between clinician and patient, as patients may not feel that their pain , the reason they are seeking treatment, is being taken seriously. Another limitation of the MMPI is its inefficiency. In the absence of any complicating factors, the 567 items of the MMPI-2 take 60 minutes or longer to be completed by an individual of average or above average intelligence .s This makes the MMPI a tedious task that can make an already anxious and irritated patient even more anxious, irritable, and uncooperative. The idea of a personality description or diagnosis is to characterize reliable patterns of psychological functioning that might allow some extrapolation to how the individual is likely to behave in the future-predictive validity. As noted, the MMPI has been used to predict responses to a variety of pain treatments. The results have proved to be equivocaI. 9 'o.,. Even when the MMPI

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does predict response to treatment, this is a probabilis tic inference regard ing successful outcome. No studies have reported that the MMPI can predict with near 100% accuracy; thus, it use with a specific case is called into question. The best that might be stated is that a patient with a specific profile has a greater probability of an unsuccessful outcome . Withholding of treatment solely on the basis of MMPI scale elevations would be a dubious practice at best. Patient response profiles might be useful for considering psycholog ical interventions as supplementary; however, how to intervene and the efficacy of such interventions have not been empirically demonstrated. Turk" concluded that MMPI profiles shed little light on the etiology of chronic pain. Thus, they remain, at best, descriptive rather than prescriptive. Given these functional limitations, along with the psychometric and structural problems noted by Main and Spansw ick and Helmes and Reddon ,8the burden of proof for continuing to use the MMPI remains on the clinician.

DOES THE MMPI ASSESS DISPOSITIONAL FACTORS RELATED TO PAIN? The MMPI was developed for the primary purpose of assisting clinicians in making diagnoses of psychopathology. The phrase personality inventory is therefore somewhat of a misnomer that may have contributed to the misuses of the MMPI. Even the original aim of assessing psychopathology was barely realized by the MMPI. A decade into its use it was revealed that the clinical scales of the MMPI were measuring something other than the syndromes suggested by the scale names.' What, then, does the MMPI measure? The answer to this question is a matter of some interpretation. Clinicians often speak of "premorbid personality traits" that predispose individuals to report pain.' As Main and Spanswick point out , however, the concepts of psychogenic pain and pain-prone personality have not received much empirical support. The infamous Conversion-V profile of the MMPI, for example, is often taken as indicative of the tendency to convert psychological distress into physical symptoms. Research , however, has found that this configuration is not characteristic of the majority of pain patients."? An important aspect of what the MMPI does assess is mood states such as depression and anxiety, which (unlike stable traits) are susceptible to change with treatment. Indeed, several invesfiqators" have noted that MMPI profiles change as a function of treatment in pain clinics, suggesting that responses on the MMPI are not indications of immutable dispositions, but may be situationally determined responses to the presence of an intractable condition, physical deconditioning, implication

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of faking or exaggerating symptoms, and medication use. The responses may reflect emotional reactions to chronic pain ratherthan causal predispositions to pain. Anxiety, for instance, has rarely been found to precipitate pain, but has been shown repeatedly to exacerbate perceived pain. Similarly, depression is a frequent consequence of chronic pain, but little empirical evidence has been presented to support its etiological significance. Thus, a within-subject reduction in scores of depression following treatment is probably attributable to a drop in dysphoric mood rather than any change in personality traits.

LANGUAGE AND MODELS OF PAIN Main and Spanswick take issue with the reliance on language in assessment instruments such as the MMPI and the McGill Pain Questionnaire, and question the association between self-reports of pain, nociception, and the experience of pain. They suggest that visual analogue scales are more effective in bridging the communication barrier between patient and clinician. The basis for this assumption is not intuitively obvious. Admittedly, individual language has its limits in describing such an ephemeral construct as pain, but there is a richness in language as a means of communicating private experiences (e.g., pain), a richness that is simply unattainable with unidimensional rating scales or observation of behavior. In a treatise on language and pain, Fabreqa' emphasizes that an individual's vernacular governs their world view and that report and experience of pain are greatly influenced by the language used to describe it. As depicted in the schematic model of chronic pain provided by Main and Spanswick, pain is a complex subjective experience comprised of psychosocial and behavioral factors, as well as physical ones. It is unavoidable that patients' self-reports will be necessary to describe their experiences. Moreover, it is the patients' appraisals and expectancies that determine their seeking treatment, self-presentation, and responses to treatment. Thus, neither objective physical measures nor quasi-objective recording of behavioral manifestations of pain, distress, or suffering will be adequate in assessment. Clearly, language is both inescapable and indispensable in psychological assessment.

CONCLUSION Our criticisms of the MMPI, unlike those of Main and Spanswick, do not imply a rejection of the whole enterprise of personality assessment. Nor do we view the personality assessment as supporting mind-body dualism. Rather, we view the MMPI as a flawed instrument

that, like many people seen on the beach, is overexposed and underdeveloped, at least for the purpose of assessing pain patients. The fact that individuals possess dispositions to respond similarly across situations seems incontrovertible. The cause for these consistent responses may be based on prior learning history and the evolution of cognitive schema for filtering information, conditioning of emotional responses, genetics, and most likely some combination of such factors. Examination of these predispositions can be important in understanding why different individuals with the same objective physical pathology respond so differently both to the trauma and the treatments provided. This is not to say that personality characteristics are causal agents in pain, but rather that individual differences affect how sensory information is processed and perceived, and the subsequent response both to symptoms and treatment. Idiosyncratic interpretations are particularly important as they relate to rehabilitation, where the patient needs to be motivated to expend effort for extended periods of time, largely outside the direct supervision of health care providers. Main and Spanswick reject the MMPI because of its theoretical and psychometric problems; we agree in large part with this, but we emphasize the functional limitations of the MMPI. Yet, as Main and Spanswick point out, the MMPI continues to be used somewhat indiscriminately in the assessment of pain. Main and Spanswick also seem to indict the whole enterprise of psychopathology and personality assessment. We differ from this point of view. As noted, dispositional factors may not have earned much currency as causal factors in pain, but they have been shown to function as moderators and concomitants of the pain experience. In view of that, they are worthy of assessment as part of a more comprehensive approach to assessing the person and not just the pain." Finally, we believe that the assessment of psychopathology and personality factors in pain may be necessary but not sufficient for fully understanding and treating the pain sufferer. Contrary to the view of Main and Spanswick, we do not believe that this fosters a mind-body dualism. Physical and psychological factors need not, indeed, should not, be viewed as independent, but rather both sets of factors contribute to the experience of pain. This is perhaps the most important lesson taught by the conceptual model underlying the gate control theory." Ultimately, assessment must focus on multiple cognitive, behavioral, affective, and biomedical influences on pain. The language the patient uses to construe his or her plight, to describe the predicament confronted, and interpret the treatment being offered cannot be eliminated. The results of this

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broad-based assessment protocol should serve as the basis for clinical decision making and the tailoring of treatment to the unique set of characteristics and needs of each individual patient." Despite our disagreements regarding the role of personality and language in chronic pain, Main and Spanswick's article is welcomed, because it challenges conventional and at times mindless thinking about assessment of chronic pain patients. Often, assessment instruments are chosen because of their longevity or title rather than demonstrated clinical utility. Main and Spanswick's stimulating article induces clinicians and clinical investigators to consider such fundamental questions as "what factors are important for understanding the behavior of chronic pain patients?," "why are these important?," and "how will information about these factors be used in clinical decision making?" Responses to such question must precede decisions about what assessment instruments will be used.

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4. Fabrega, H: Language, culture and the neurobiology of pain: a theoretical exploration. Behav Neurol 2:235-260, 1989 5. Graham JR: MMPI-2: assessing personality and psychopathology. Oxford, New York, 1993 6. Hathaway SR, McKinley JC: A multiphasic personality schedule (Minnesota): I. Construction of the schedule. J Psychol 10:249-254, 1940 7. Helmes E: What types of useful information do the MMPI and MMPI-2 provide on patients with chronic pain? APS Bull 4:1-25, 1994 8. Helmes E, Reddon JR: A perspective on developments in assessing psychopathology: a critical review of the MMPI and MMPI-2. Psychol Bull 113:453-471, 1993 9. Love AW, Peck CL: The MMPI and psychological factors in chronic low back pain: a review. Pain 28:1-12, 1987 10. McCreary, CP: Psychological evaluation of chronic pain with the MMPI. Pain Digest 3:246-251 , 1993 11. Mellman PW, Guck TP, Skultety FM, Robbins DE, Jensen K: Changes in psychopathology associated with multidisciplinary pain treatment. Clin J Pain 2:107-113,1986 12. Melzack R, Wall PO: Pain mechanisms: a new theory. Science 50:971-979, 1965 13. Naliboff BD, Cohen MJ, Yellen AN: Frequency of MMPI profile types in three chronic illness populations. J Clin Psycho/39:843-847,1983 14. Turk DC: Custom izing treat ment for chron ic pain patients: who, what, and why. Clin J Pain 6:255-270, 1990 15. Turk DC: Assess the person, not just the pain. Pain: Clin Updates 1:1-4, 1993