Tom G. Mayer

Psychiatric Illness and Chronic Low-back Pain: The Mind and the Spine—which Goes First?

Two hundred chronic low-back pain patients entering a functional restoration program were assessed for current and lifetime psychiatric syndromes using a structured psychiatric interview to make DSM-III-R diagnoses. Results showed that, even when the somewhat controversial category of somatoform pain disorder was excluded, 77% of patients met lifetime diagnostic criteria and 59% demonstrated current symptoms for at least one psychiatric diagnosis. The most common of these were major depression, substance abuse, and anxiety disorders. In addition, 51% met criteria for at least one personality disorder. All of the prevalence rates were significantly greater than the base rate for the general population. Finally, and most importantly, of these patients with a positive lifetime history for psychiatric syndromes, 54% of those with depression, 94% of those with substance abuse, and 95% of those with anxiety disorders had experienced these syndromes before the onset of their back pain. These are the first results to indicate that certain psychiatric syndromes appear to precede chronic iow-back pain (substance abuse and anxiety disorders), whereas others (specifically, major depression) develop either before or after the onset of chronic low-back pain. Such findings substantially add to our understanding of causality and predisposition in the relationship between psychiatric disorders and chronic low-back pain. They also clearly reveal that clinicians should be aware of potentially high rates of emotional distress syndromes in chronic low-back pain and enlist mental health professionals to help maximize treatment outcomes.

1985 volvo award in clinical sciences objective assessment of spine function following industrial injury a prospective study with comparison group and one-year follow-up

Objective functional capacity measurement techniques were used to guide a treatment program for a group of 66 chronic back pain patients. These patients were compared with a group of 38 chronic patients who were not administered the treatment program. Outcome data were collected by telephone survey at an average 1 year follow-up. In addition, functional capacity measures were collected for treatment group patients on admission and follow-up evaluations. Results demonstrated that the functional capacity measures collected for the treatment group improved in approximately 80% of the patients. These changes were also accompanied by positive changes in psychologic measures. In addition, at 1 year follow-up, the treatment group had approximately twice the rate of patients who returned to work, relative to the comparison group. Additional surgery rates were comparable for both groups (6% in the treatment and 7% in the comparison group), but the frequency of additional health-care professional visits was substantially higher in the comparison group. The findings suggest that quantitative functional capacity measures can give objective evidence of patient physical abilities and degree of effort and can significantly guide the clinician in administering an effective treatment program

Quantification of lumbar function. Part 2: Sagittal plane trunk strength in chronic low-back pain patients.

A prototype sagittal plane trunk strength tester was used to measure trunk strength in 286 chronic low-back pain patients. Initial data for this patient group are compared with data acquired previously from a group of controls, adjusted for age, sex, and body weight. Distinct patterns characterize the patient sample as opposed to the controls: (1) Patient values for both flexors and extensors were markedly decreased, with greater variability; (2) Extensor strength was affected more significantly than flexor strength; (3) Discrepancies between patients and controls were greater for females than for males; (4) Highspeed dropoff ratios were much lower for patients, both in flexion and extension. These results demonstrate that strength deficits are a major factor in the deconditioning syndrome associated with chronic low-back pain.

Comparison of Ct Scan Muscle Measurements and Isokinetic Trunk Strength in Postoperative Patients

The present study compared the computed tomography (CT) scan muscle area/muscle density and isokinetic trunk strength of a group of spinal surgery patients (35 males and 11 females) 3 months postoperatively. Analyses showed trunk strength means to be below 50% of gender-specific “normal” values obtained by evaluating a normative sample. Extensor strength was more significantly affected than flexors. Single-cut CT scans performed at the time of isokinetic trunk strength assessment demonstrated psoas and erector spinae atrophy through a significant decrease in muscle density, with only a trend towards decreased cross-sectional area. Findings also indicated that there was a significant correlation between increased mechanical trunk strength performance and greater muscle density on CT scan. Strength was significantly lower for the male patients undergoing spinal fusion compared with those undergoing disc excision. However, no significant difference was found in strength measures between: males with high versus low pain level and working versus nonworking males at the time of evaluation.

Progressive isoinertial lifting evaluation: I. A standardized protocol and normative database

Dynamic tests of trunk strength and lifting capacity have become more popular in recent years, offering certain advantages over static isometric tests in measuring patient progress in functional restoration programs for spinal disorders. However, equipment for performing such tests is expensive to buy, complex to run, and requires technical expertise and clinical volume unavailable in most physician offices. In this study, a new dynamic test known as Progressive Isoinertial Lifting Evaluation (PILE) is described, which draws upon prior psychophysical and isoinertial methods. An industrial sample of 61 male and 31 female incumbent workers were tested using the PILE, and a variety of anthropometric normalizing factors were evaluated. The isolation of an “Adjusted Weight” (AW) normalizing factor is documented, after which normative data are presented for male and female workers utilizing lumbar (0–30 inches) and cervical (30–54 inches) dynamic protocols.

Quantification of lumbar function. Part 1: Isometric and multispeed isokinetic trunk strength measures in sagittal and axial planes in normal subjects.

The goals of this study were to: (1) evaluate the repeatability of a method of measuring trunk strength; (2) measure isometric and isokinetic strength of trunk flexors, extensors and rotators; (3) explore relationships among these muscle groups; and (4) compare a torque to body weight adjustment measure versus lean body weight. One hundred twenty-five normal subjects (62 males, 63 females) were tested using a Cybex prototype trunk extension-flexion system. Sixty-seven subjects (25 males, 42 females) were tested using a prototype torso rotation unit. Fifty were tested on both devices. Results demonstrated that the strength data were reliable, with strength being greatest in extension. The following were also learned-torque output declined slightly with increased speed; extensor-flexor strength remained consistent from 18 to 44 years; extension-flexion ratios exceeded 1.1:1; left to right rotation ratios remained 1:1; there was no significant difference between torque adjusted to body weight or to lean body weight.

The pain disability questionnaire: a new psychometrically sound measure for chronic musculoskeletal disorders.

Study Design. The Pain Disability Questionnaire (PDQ) is a psychometric evaluation study of a new measure of functional status. Objective. To evaluate the psychometric properties of the PDQ and compare its validity and responsiveness to traditional measures of functional status, such as the Oswestry, Million (MVAS), and SF-36 instruments. Summary of Background Data. Measuring clinical outcomes is an essential element of any musculoskeletal treatment. The PDQ was developed for this purpose. It yields a total functional disability score ranging from 0 to 150. The focus, much like other health inventories, is primarily on disability and function. However, unlike most other measures, this instrument is designed for the full array of chronic disabling musculoskeletal disorders (CDMDs), rather than low back pain alone. Further, psychosocial variables, which recent studies have shown to play an integral role in the development and maintenance of chronic pain disability, formed an important core of the PDQ. Methods. Four groups were used in this psychometric evaluation: an asymptomatic normative population (NP; n = 50), an acute musculoskeletal disorder population (AMD; n = 52), a chronic disabled musculoskeletal disorder population (CDMD; n = 230), and a heterogeneous pain population (HP; n = 114). The NP and AMD groups served as comparison samples for the CDMD and HP groups. Analyses of PDQ reliability, validity, and responsiveness were conducted. Results. Test-retest reliability coefficients (ranging from 0.94 to 0.98) and a Cronbach’s alpha coefficient of 0.96 for the PDQ were found to be of excellent quality. The responsiveness of the PDQ, as measured by Cohen’s effect size statistic, ranged from 0.85 to 1.07, better than the Oswestry, MVAS, and SF-36. A high level of face validity was observed for the PDQ, as the CDMD population exhibited significantly higher pretreatment PDQ scores than a group of patients suffering from acute injuries. The construct-related validity of the PDQ was also found to be of excellent quality, as it correlated well to both the MVAS (0.65-0.81) and Oswestry (0.55-0.80). The PDQ consistently demonstrated stronger correlation coefficients to a wide variety of physical and psychosocial measures of human function, such as the SF-36, Beck Depression Inventory, Hamilton-D, State-Trait Anxiety Scale, and Pain Intensity VAS, than either the Oswestry or MVAS. A factor analysis of the PDQ revealed two factors: a Functional Status Component (FSC) and a Psychosocial Component (PC). Analyses proved each of these two components to be valid in assessing their theorized constructs. Conclusions. The present study represents a comprehensive psychometric evaluation of a new functional status measure for musculoskeletal conditions in general, and a CDMD population in particular. The psychometric properties of the PDQ are excellent, demonstrating strong reliability, responsiveness, and validity, relative to many other existing measures of functional status. The many weaknesses cited for some of the existing measures were taken into account in designing this instrument. Consequently, the characteristics commonly noted as weaknesses for these other measures (such as a restriction to only the low back pain population, and inconsistent responsiveness) can be cited as strengths of the PDQ. Its generalizability and utility for assessing orthopedic treatment progress and functional outcomes must now be evaluated in broader settings.

Prevalence of psychiatric disorders in patients with chronic disabling occupational spinal disorders.

Study Design. A prevalence study. Objectives. To assess the prevalence of psychiatric disorders among a large group of patients with chronic disabling occupational spinal disorders (CDOSDs), using a reliable and valid diagnostic instrument. Summary of Background Data. Although unrecognized and untreated psychiatric disorders have been found to interfere with successful treatment of CDOSD patients, little data are currently available regarding the psychiatric characteristics of patients claiming work-related injuries that result in CDOSDs. Methods. Psychiatric disorders in a consecutive group of CDOSD patients (n = 1,323) attending a tertiary referral center for patients with CDOSD were diagnosed using the Diagnostic and Statistical Manual of Mental Disorders. Results. Overall prevalence of psychiatric disorders was found to be significantly elevated in CDOSD patients compared with base rates in the general population. A majority (65%) of patients were diagnosed with at least one current disorder (not including Pain Disorder, which is nearly universal in this population), compared with only 15% of the general population. Major Depressive Disorder (56%), Substance Use Disorders (14%), Anxiety Disorders (11%), and Axis II Personality Disorders (70%) were the most common diagnoses. Conclusions. Clinicians treating CDOSD patients must be aware of the high prevalence of psychiatric disorders in this population. They must also be prepared to use mental health professionals to assist them in identifying and stabilizing these patients. Failure to follow a biopsychosocial approach to treatment will likely contribute to prolonged disability in a substantial number of these chronic pain patients.

Prevalence of psychiatric disorders in patients with chronic work-related musculoskeletal pain disability.

The cost and prevalence of chronic work-related musculoskeletal pain disability in industrialized countries are extremely high. Although unrecognized psychiatric disorders have been found to interfere with the successful rehabilitation of these disability patients, few data are currently available regarding the psychiatric characteristics of patients claiming work-related injuries that result in chronic disability. To investigate this issue, a consecutive group of patients with work-related chronic musculoskeletal pain disability (n = 1595), who started a prescribed course of tertiary rehabilitation, were evaluated. Psychiatric disorders were diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders. Results revealed that overall prevalences of psychiatric disorders were significantly elevated in these patients compared with base rates in the general population. A majority (64%) of patients were diagnosed with at least one current disorder, compared with only 15% of the general population. However, prevalences of psychiatric disorders were elevated in patients only after the work-related disability. Such findings suggest that clinicians treating these patients must be aware of the high prevalence of psychiatric disorders and be prepared to use mental health professionals to assist in identifying and stabilizing these patients. Failure to follow a biopsychosocial approach to treatment will likely contribute to prolonged pain disability in a substantial number of these patients.

Minimal clinically important difference.

Historically, clinical measures used to assess treatment outcome have focused primarily on reliability and validity. The issue of patient responsiveness (i.e., a measure’s ability to detect change over time) was not widely studied. More recently, however, the topic of clinical relevance has received increasing emphasis, as both clinicians and researchers endeavor to determine a treatment’s practical clinical importance, rather than just merely its statistical significance. One such approach is the concept of a minimal clinically important difference (MCID). Even though there have been attempts to come up with the optimum MCID measure, Sprattrecently noted that: “ ... Over the last 30 years, an array of approaches for assessing MCID has evolved with little concern on which approach applies in any given situation” (p 1722). During this time period, many clinical researchers may have been led astray by articles purportedly measuring MCID, without a clear understanding of the lack of consensus on appropriate methods for determining and using the MCID. Even the Federal Drug Administration had earlier called for an attempt to develop some viable and objective guidelines on the use of the MCID. However, the link to the finalized “Guidance Document on Patient-Reported Outcomes” has removed any mention of the MCID, and has recommended using standardized effect size statistics. Thus, the initial “glitter” and attractiveness of the MCID has apparently waned, probably due to the fact of the methodologic weakness of it. At the outset, readers should also be aware that there is currently no agreed on “right” or “wrong” MCID methodology that is recommended across clinical trials, be they surgical, pharmacological, or noninterventional. Because of the increasing number of MCID articles published in orthopedic journals, including many recent ones in Spine, it was felt necessary to discuss some of the often complicated issues involved in using an MCID in clinical outcomes research.