Diagnostic accuracy of technologies used in low back pain assessment. Thermography, triaxial dynamometry, spinoscopy, and clinical examination

Intrarater Reliability of Digital Thermography in Detecting Pin Site Infection: A Proof of Concept Study

Aim and objective

The purpose of this study was to explore the capability and Intrarater reliability of thermography in detecting pin site infection.

Materials and methods

This is an explorative proof of concept study. Clinical assessment of pin sites was performed by one examiner with the Modified Gordon Pin Infection Classification from grade 0 to 6. Thermography of the pin sites was performed with a FLIR C3 camera. The analysis of the thermographic images was done in the software FLIR Tools. The maximum skin temperature around the pin site and the maximum temperature for the whole thermographic picture were measured. An Intrarater agreement was established and test-retests were performed with different camera angles.

Results

Thirteen (four females, nine males) patients (age 9–72 years) were included. Indications for frames: Fracture (n=4), two deformity correction, one lengthening and six bone transport. Days from surgery to thermography ranged from 27 to 385 days. Overall, 231 pin sites were included. Eleven pin sites were diagnosed with early signs of infection: five grade 1, five grade 2 and one grade 3. Mean pin site temperature for each patient was calculated, varied between patients from 29.0°C to 35.4°C (mean 33.9°C). With 34°C as cut-off value for infection, sensitivity was 73%; specificity, 67%; positive predictive value, 10%; and negative predictive value, 98%. Intrarater agreement for thermography was ICC 0.85 (0.77–0.92). The temperature measured was influenced by the camera positioning in relation to the pin site with a variance of 0.2.

Conclusions

Measurements of pin site temperature using the hand-held FLIR C3 infrared camera was a reliable method and the temperature was related to infection grading.

Clinical significance

This study demonstrated that digital thermography with a hand-held camera might be used for monitoring the pin sites after operations to detect early infection.

How to cite this article

Rahbek O, Husum HC, Fridberg M, et al. Intrarater Reliability of Digital Thermography in Detecting Pin Site Infection: A Proof of Concept Study. Strategies Trauma Limb Reconstr 2021;16(1):1–7.

Repeatability of infrared plantar thermography in diabetes patients: a pilot study

OBJECTIVE

Infrared (IR) thermography has been used as a complementary diagnostic method in several pathologies, including distal diabetic neuropathy, by tests that induce thermoregulatory responses, but nothing is known about the repeatability of these tests. This study aimed to assess the repeatability of the rewarming index in subjects with type 2 diabetes mellitus (T2DM) and nondiabetic control subjects.

METHODS

Using an IR camera, plantar IR images were collected at baseline (pre-) and 10 min after (post-) cold stress testing on two different days with 7 days interval. Plantar absolute average temperatures pre- and post-cold stress testing, the difference between them (ΔT), and the rewarming index were obtained and compared between days. Repeatability of the rewarming index after the cold stress test was assessed by Bland-Altman plot limits of agreement.

RESULTS

Ten T2DM subjects and ten nondiabetic subjects had both feet analyzed. Mean age did not differ between groups (p = .080). Absolute average temperatures of plantar region pre- (p = .033) and post-cold stress test (p = .019) differed between days in nondiabetic subjects, whereas they did not differ in T2DM subjects (pretest, p = .329; post-test, p = .540). ΔT and rewarming index did not differ between days for both groups, and the rewarming index presented a 100% agreement of day-to-day measurements from T2DM subjects and 95% with nondiabetic subjects.

CONCLUSIONS

The rewarming index after cold stress testing presented good repeatability between two days a week in both groups. Despite T2DM subjects presenting no differences on absolute temperature values between days, ΔT or rewarming index after cold stress testing remain recommended beside absolute temperature values for clinical use.

Skin temperature changes in patients with unilateral lumbosacral radiculopathy

Objective

To clarify the relationship of skin temperature changes to clinical, radiologic, and electrophysiological findings in unilateral lumbosacral radiculopathy and to delineate the possible temperature-change mechanisms involved.

Methods

One hundred and one patients who had clinical symptoms and for whom there were physical findings suggestive or indicative of unilateral lumbosacral radiculopathy, along with 27 normal controls, were selected for the study, and the thermal-pattern results of digital infrared thermographic imaging (DITI) performed on the back and lower extremities were analyzed. Local temperatures were assessed by comparing the mean temperature differences (ΔT) in 30 regions of interest (ROIs), and abnormal thermal patterns were divided into seven regions. To aid the diagnosis of radiculopathy, magnetic resonance imaging (MRI) and electrophysiological tests were also carried out.

Results

The incidence of disc herniation on MRI was 86%; 43% of patients showed electrophysiological abnormalities. On DITI, 97% of the patients showed abnormal ΔT in at least one of the 30 ROIs, and 79% showed hypothermia on the involved side. Seventy-eight percent of the patients also showed abnormal thermal patterns in at least one of the seven regions. Patients who had motor weakness or lateral-type disc herniation showed some correlations with abnormal DITI findings. However, neither pain severity nor other physical or electrophysiological findings were related to the DITI findings.

Conclusion

Skin temperature change following lumbosacral radiculopathy was related to some clinical and MRI findings, suggesting muscle atrophy. DITI, despite its limitations, might be useful as a complementary tool in the diagnosis of unilateral lumbosacral radiculopathy.

Acute lower back pain mapped by dermatomal scarification in urban Malawi

Lower back pain is a problem that affects many and generates an economic burden on the National Health Service. In modern days, although it is tempting to rely on specialist imaging for the initial investigation of back pain, it is often unnecessary. Comprehensive clinical examination is immediately available and should detect neurological impairments where they exist. A 32-year-old man from Malawi presented to clinic with lower back pain radiating to the right leg. Inspection revealed traditional scarification marks along the classical path of lumbar nerve root, which coincided with his L5 dermatomal pain. The distribution of his 'Mphini' along the typical path of lumbar nerve was identical to his myelography. This report strongly illustrates that in the Western medical setting, accurate history and examination would have allowed correct interpretation of these symptoms and correctly indicated the need for myelography.

Plantar Infrared Thermography Measurements and Low Back Pain Intensity

OBJECTIVE

To study the skin temperature disorders in low back pain (LBP) patients compared with reference persons without LBP and to evaluate the relationship between pain intensity and other clinical signs and temperature abnormalities.

METHODS

Sixty-five patients with unilateral chronic LBP with or without referred nonradicular leg pain (29 men and 36 women; age range, 30-51 years) and 20 reference persons without LBP (7 men and 13 women; age range, 30-49 years) participated in this study. The pain level was recorded by the use of a visual analog scale (0-100). Questionnaires and a series of spinal mobility tests (the modified Schober, straight leg-raising test, finger-floor distance, side bending) were used. Thermographic images of the low back area and legs (anterior, lateral, and posterior surfaces and the plantar surfaces of feet) were taken with an infrared video camera.

RESULTS

The temperature changes in the plantar surface correlated with LBP intensity. The pain levels differed in the groups with the different types of temperature changes. There were significant lower extremity regional skin temperature alterations (at least 1 regional interside difference more than 0.3 degrees C) in most cases both in LBP patients and in reference persons, but plantar interside temperature difference was significantly higher in LBP patients.

CONCLUSION

Temperature changes of the plantar surface seem to be connected with LBP intensity. Temperature measurements may be useful as an adjunctive physiological test in the evaluation and documentation of autonomic dysfunction in LBP patients.

Touch the pain away: new research on therapeutic touch and persons with fibromyalgia syndrome

This pilot study tested the effectiveness of 6 therapeutic touch treatments on the experience of pain and quality of life for persons with fibromyalgia syndrome. Its findings support that subjects who received therapeutic touch had a statistically significant decrease in pain for each pretherapeutic to posttherapeutic touch treatment, as well as significant improvement in quality of life from pre-first to pre-sixth treatment. Therapeutic touch may be an effective treatment for relieving pain and improving quality of life in this specific population of persons with fibromyalgia syndrome.

Reliability of clinical tests in the assessment of patients with neck/shoulder problems-impact of history

STUDY DESIGN

A clinical trial on patients receiving neck/shoulder physical examinations.

OBJECTIVES

To analyze reliability of clinical tests, prevalence of positive findings in the assessment of neck/shoulder problems in primary care patients, and the impact of history, including pain drawing, on these parameters.

SUMMARY OF BACKGROUND DATA

Reliability of clinical tests varies, perhaps partly because of the impact of history. To our knowledge, this has not been studied before.

METHODS

Two examiners independently assessed 100 patients with a set of 66 clinical tests divided into 9 categories. Half of the patients were examined with and the other half without knowledge of history. Reliability as expressed by percentage agreement, kappa coefficients, and prevalence of positive findings was calculated.

RESULTS

Reliability of clinical tests was poor or fair in several categories and did not alter with history. Only a bimanual sensitivity test reached good kappa values. With known history, prevalence of positive findings increased. Bias was apparent in all test categories except sensitivity tests. Four out of five patients were diagnosed to have neurogenic dysfunction in the affected area.

CONCLUSIONS

Our sensitivity test was the most reliable and also exempt from bias and should be studied further. Some common tests may not be reliable. History had no impact on reliability of our tests but increased the prevalence of positive findings. Neurogenic dysfunction seems very common in patients with neck and/or shoulder problems and should be screened for.

Content validity of manual spinal palpatory exams - A systematic review

BACKGROUND

Many health care professionals use spinal palpatory exams as a primary and well-accepted part of the evaluation of spinal pathology. However, few studies have explored the validity of spinal palpatory exams. To evaluate the status of the current scientific evidence, we conducted a systematic review to assess the content validity of spinal palpatory tests used to identify spinal neuro-musculoskeletal dysfunction.

METHODS

Review of eleven databases and a hand search of peer-reviewed literature, published between 1965-2002, was undertaken. Two blinded reviewers abstracted pertinent data from the retrieved papers, using a specially developed quality-scoring instrument. Five papers met the inclusion/exclusion criteria.

RESULTS

Three of the five papers included in the review explored the content validity of motion tests. Two of these papers focused on identifying the level of fixation (decreased mobility) and one focused on range of motion. All three studies used a mechanical model as a reference standard. Two of the five papers included in the review explored the validity of pain assessment using the visual analogue scale or the subjects' own report as reference standards. Overall the sensitivity of studies looking at range of motion tests and pain varied greatly. Poor sensitivity was reported for range of motion studies regardless of the examiner's experience. A slightly better sensitivity (82%) was reported in one study that examined cervical pain.

CONCLUSIONS

The lack of acceptable reference standards may have contributed to the weak sensitivity findings. Given the importance of spinal palpatory tests as part of the spinal evaluation and treatment plan, effort is required by all involved disciplines to create well-designed and implemented studies in this area.

Assessment of trunk function in single and multi-level spinal stenosis: a prospective clinical trial

OBJECTIVE

To clarify the biomechanical indicators of single- and multi-level stenosis and to determine the biomechanical outcome of selective conservative decompression.

DESIGN

This study is a prospective clinical trial examining trunk function in spinal stenosis patients operated using a conservative procedure in an orthopaedic clinic.

BACKGROUND

Although several clinical studies have examined the instability and motion characteristics of operated lumbar spinal canal stenosis, few if any studies have prospectively examined the biomechanical outcome of lumbar spinal canal stenosis surgery.

METHODS

Comprehensive pre- and post-operative trunk dynamometer strength and motion analysis tests were performed on 36 patients operated for lumbar canal stenosis. Surgical treatment efficacy was evaluated within a three variable crossed factorial design considering stenosis classification, number of operative levels, and changes in several trunk biomechanical outcomes from pre- to post-operative assessment. Patients were evaluated after a minimum one-year follow-up.

RESULTS

Pre-operatively there were no differential effects associated with stenosis classification or number of operated levels. There was a significant post-operative increase in isometric trunk extension torque and flexion-extension power and a return to a more normal trunk extension-flexion torque ratio. Patients with mixed, single level stenosis demonstrated greater trunk extension power both pre- and post-operatively compared to other patients.

CONCLUSIONS

Conservative surgical treatment of lumbar spinal stenosis produced a marked improvement in the functional mechanical status of the low back.

RELEVANCE

This study assists clinicians and researchers to understand trunk function following conservative surgical treatment of lumbar spinal stenosis.

Relationship between functional evaluation measures and self-assessment in nonacute low back pain

STUDY DESIGN

The correlations between objective biomechanical indicators of function and self-assessment scores were examined retrospectively for 91 subjects with nonacute low back pain.

OBJECTIVES

To examine the correlation between self-assessment, trunk range of motion (ROM), velocity, and complex mechanical coordination patterns of the spine in nonacute low back pain.

SUMMARY OF BACKGROUND DATA

In low back pain, there is often little concordance between pain, physical impairment, and disability. Use of range of motion and velocity to enhance objectivity in impairment evaluations has been ineffectual. In this study, two hypotheses were examined: range of motion and velocity are controllable and inherently correlated with self-assessment; complex spinal coordination patterns such as range of lordosis cannot be controlled and are independent of self-assessment.

METHODS

Self-assessment questionnaires were administered, and indexes of spinal motion and coordination were measured through skin marker kinematics. The correlation between self-assessments and biomechanical measures was determined.

RESULTS

Self-assessments of function were significantly correlated with parameters prone to regulation: range of motion, velocity, and load lifted. In contrast, little correlation was found with measures of complex spinal coordination less susceptible to conscious or affective regulation, namely, range of lordosis and estimated segmental mobility. This effect was magnified with increased load. Self-assessment scores were significantly poorer among insurance referrals, regardless of functional status.

CONCLUSIONS

Simple parameters of the functional examination, such as range of motion and velocity, are strongly correlated with cognitive state, and thus the information they supply is less than ideal. Complex spinal coordination is a better indicator of the degree of spinal dysfunction and enhances the process of differentiating between pain, disability, and functional impairment.

Evaluation and management of occupational low back disorders

This clinical practice review of occupational low back disorders describes work-related risk factors, occupational history, physical evaluation, clinical tests, diagnosis, care, and prevention. It is part of a quality assurance (QA) and quality improvement (QI) effort to establish exemplary occupational practice standards. It emphasizes the involvement of occupational medicine physicians in exposure assessment, care of injured workers, and disease prevention. Important occupational risk factors such as lifting, awkward body posture and vibration, in addition to psychosocial, socio-economic and other factors are summarized. The focus is on mechanical back disorders. Return-to-work, rehabilitation and prevention strategies are discussed as part of integrated disability management involving the injured worker, the primary care provider, employers and other relevant parties.

Chronic pain disability exaggeration/malingering and submaximal effort research

OBJECTIVE

This is the first review of chronic pain (CP) malingering/disease simulation research. The purpose of this review was to determine the prevalence of malingering within CP patients (CPPs), whether evidence exists that malingering can be detected within CPPs, and to suggest some avenues of research for this topic.

DESIGN

A computer and manual literature search produced 328 references related to malingering, disease simulation, dissimulation, symptom magnification syndrome, and submaximal effort. Of these, 68 related to one of these topics and to pain. The references were reviewed in detail, sorted into 12 topic areas, and placed into tabular form. These 12 topic areas addressed the following: existence of malingering within the CP setting; dissimulation, identification simulated (faked) facial expressions of pain; identification of malingering by questionnaire; identification of malingered sensory impairment; identification of malingered loss of hand grip strength; identification of submaximal effort by isometric strength testing; identification of submaximal or malingered effort by isokinetic strength testing; identification of submaximal or malingered effort by the method of coefficient of variation; self-deception; symptom magnification syndrome; and miscellaneous malingering identification studies. Each report, in each topic area, was rated for scientific quality according to guidelines developed by the Agency for Health Care, Policy and Research (AHCPR) for rating the level of evidence presented in the reviewed study. The AHCPR guidelines were then used to rate the strength and consistency of the research evidence in each topic area based on the type of evidence the reports represented. All review conclusions were based on the results of these ratings.

SETTING

Any medical setting reporting on either malingering or disease simulation, or dissimulation, or submaximal effort and pain.

PATIENTS

Normal volunteers, CPPs, or any group asked to produce a submaximal or malingered effort or a malingered test profile.

RESULTS

The reviewed studies indicated that malingering and dissimulation do occur within the CP setting. Malingering may be present in 1.25-10.4% of CPPs. However, because of poor study quality, these prevalence percentages are not reliable. The study evidence also indicated that malingering cannot be reliably identified by facial expression testing, questionnaire, sensory testing, or clinical examination. There was no acceptable scientific information on symptom magnification syndrome. Hand grip testing using the Jamar dynamometer and other types of isometric strength testing did not reliably discriminate between a submaximal/malingering effort and a maximal/best effort. However, isokinetic strength testing appeared to have potential for discriminating between maximal and submaximal effort and between best and malingered efforts. Repetitive testing with the coefficient of variation was not a reliable method for discriminating a real/best effort from a malingered effort.

CONCLUSIONS

Current data on the prevalence of malingering within CPPs is not consistent, and no conclusions can be drawn from these data. As yet, there is no reliable method for detecting malingering within CPPs, although isokinetic testing shows promise. Claims by professionals that such a determination can be made should be viewed with caution.

Improving the evaluation of benign low back pain

STUDY DESIGN

A prospective, blind study was conducted to investigate the factors underlying the decisions of expert clinicians in diagnosis of acute, benign low back pain, compared with results obtained with an automated physical examination by machine. From the results, a strategy to significantly improve clinical diagnosis in cases of discordance was determined.

OBJECTIVES

To identify factors in the clinical assessment of low back pain that indicate when independent diagnostic testing would be useful.

SUMMARY OF BACKGROUND DATA

The clinical evaluation of low back pain is often dominated by subjective reports of pain. Published medical literature has underscored several inherent weaknesses of the clinical examination, and concerns have been raised about its effectiveness for assessing patients with low back pain. Thus, it has been proposed that objective measures to complement the clinician's examination would be beneficial in the formulation of dependable diagnoses.

METHODS

Randomly designated subjects, who in describing their conditions were objective or role playing, were assessed by clinicians and a machine for diagnosis of low back pain assessment versus normal backs. Each subject's pain assessment was compared with a gold standard that was established by experts in low back pain. Components of the clinical examination were analyzed to assess which were the most informative in making a reliable diagnosis. The information content of the machine assessment was also analyzed and a strategy to complement the clinical diagnosis with the machine diagnosis determined.

RESULTS

Discordance among the various components of the clinical examination was a strong indicator of when the efficacy of the clinical examination dropped below a random level of decision making. When there was discordance, incorporating the functional evaluation by machine into the clinical diagnosis improved the performance of the clinician. Notably, in nonobjective subjects, the accuracy of diagnosis was enhanced by as much as 69%.

CONCLUSIONS

It is possible to improve the accuracy of clinical diagnosis by incorporating a functional evaluation by machine when there is discordance between physical examination findings and reported pain.

Thermographic diagnostics in equine back pain

Infrared thermographic imaging (ITI) is the most sensitive objective imaging currently available for the detection of back disease in horses. It is, however, only a physiological study primarily of vasomotor tone overlying other superficial tissue factors. Interpretation requires extreme care in imaging protocol and in understanding the significance of altered sympathetic nervous tone and the sympathetic distribution. Most discussions on back pain have centered on nociception and inflammatory events. ITI provides information and localization for more significant than diagnosing areas of hot spots. Chronic back pain usually involves vasoconstriction at the affected sites and from ITI studies in man, we have an opportunity to appreciate chronic pain phenomena that involves non-inflammatory events. These occur commonly in horses, but are still seldom recognized and treated.

Is work status of low back pain patients best described by an automated device or by a questionnaire?

STUDY DESIGN

A prospective cohort study of patients with subacute occupational back pain.

OBJECTIVES

To study the relation between a marketed opto-electric device measuring trunk kinematics, a widely used specific functional capacity questionnaire, and work status in back pain patients, and to assess the responsiveness to change in work status of the opto-electric device and the questionnaire.

SUMMARY OF BACKGROUND DATA

Several instruments have been developed to evaluate the functional capacities of patients with back pain, but the relation between these instruments and work status has rarely been studied.

METHODS

The relation between the opto-electric device, the questionnaire, and work status in patients with back pain was evaluated. The study population was a prospective cohort of patients with subacute back pain who were absent from regular work for more than 4 weeks. All data were compiled blindly on the same day, at study entry (4 weeks after work accident), and at 12, 24, and 52 weeks after the work accident. The validity of the questionnaire and opto-electric device scores was assessed with partial correlation analyses, standardized response mean, logistic regression analyses, and receiver operating characteristics curves.

RESULTS

The correlation between the questionnaire and opto-electric device scores was low. The questionnaire scores were significantly related to work status, but the opto-electric device scores were not. The questionnaire was responsive to change in work status, whereas the opto-electric device was not.

CONCLUSIONS

The opto-electric device scores were not related to either functional capacity scores (questionnaire) or work status in patients with low back pain, and the opto-electric device was not responsive to change in work status. Conversely, the questionnaire was related to work status and was responsive to change in work status.

Evaluation of clinician and machine performance in the assessment of low back pain

STUDY DESIGN

A prospective blind study to test and compare the performance of clinicians (evaluators) with that of an automated machine (the Spinoscope) in conducting an examination on randomly designated simulators/dissimulators and honest subjects to assess acute benign low back pain.

OBJECTIVES

To test the impact of reported pain and history on the clinical examination and to compare the ability of clinicians and the machine to recognize normal findings in a controlled group of subjects with and without benign low back pain.

BACKGROUND

The literature raises serious questions regarding the efficacy of the clinical examination for patients with low back pain.

METHODS

A "gold standard" (clinical examination by experts in low back pain) was established against which the clinical examination by the evaluators and the machine assessment (incorporating weight-lifting ability) of honest subjects and simulators/dissimulators were compared using the receiver operating characteristic technique. The selection of subjects was performed according to strict inclusion and exclusion criteria.

RESULTS

The evaluators were more accurate with the honest subjects, the machine more accurate with the simulators/dissimulators, and, for the entire population tested, the they were equivalent in accuracy (71% vs. 72% concordance). Results from the machine's expert system and from clinician readers of the machine data compared favorably. The machine's concordance with the gold standard increased with increasing loads lifted by the subject.

CONCLUSION

By relying primarily on the subject's self-presentation, often to the exclusion of objective findings, the clinician may err in evaluating low back function when the patient does not report his or her true condition. The additional functional analysis provided by the machine offers the clinician objective, pertinent information to complement the findings from the clinical examination.

The impact of inefficient clinical diagnosis on the cost of managing low back pain

The clinical examination remains the pivotal factor in evaluating low back pain (LBP) for decisions concerning compensation and rehabilitation. Many practitioners believe it to be highly reliable, even though existing literature does not support this belief. Not only are there no data supporting the efficacy of clinical diagnosis for LBP, but also published data underscore its many inherent weaknesses. Healthcare risk managers need accurate clinical information to make decisions. If current clinical information is unreliable, then healthcare risk management strategies for LBP must be revised. This article reviews the work of many researchers in their attempts to unravel the problem of diagnosing LBP. The following conclusions were reached: The problem is significant and continues to increase. The problem is rooted in the clinician's strong dependency on reported pain, which may not always be a reliable source of objective information. Quantification of the impact of the objectivity of reported pain on clinical performance demonstrates the need for a independent source of functional data that can improve the diagnosis. Technology exists to complement the clinical examination, improve clinical performance, and thus reduce the cost associated with LBP management. The research results presented in this article unveil disturbing findings for healthcare risk managers. The strong bias clinicians reserve for reported pain may lead them to overrate pathology, treat patients inappropriately, prescribe unnecessary imaging tests, and generate unfounded medical opinions that are responsible for many disputes. Data are presented to demonstrate the financial benefits that result from the introduction of systematic objective controls via technology. These sound management principles allow the risk manager to determine the validity of claims and treatment proposals. Risk managers can then make informed decisions on contentious claims and regulate the large number of clinician-supported disability cases--decisions that represent significant savings.

How to recognize and treat specific low back pain?

A wide variety of mechanical and non-mechanical disorders are associated with the clinical symptom of low back pain. Mechanical disorders are the cause of the vast majority of low back pain. Despite this frequency, the specific cause of mechanical low back pain can not be elucidated in spite of extensive diagnostic evaluation in a majority of individuals. Specific causes of low back pain are associated with less frequently occurring systemic illnesses including rheumatic, infectious, neoplastic, gynaecological and vascular disorders. The diagnostic process is more successful in identifying systemic disorders as the specific cause of low back pain. Non-surgical management is effective therapy with most patients with mechanical disorders of any form. Systemic illnesses require interventions directed specifically at healing the affected organ system.

Diagnostic and management procedures for compensable back injuries without serious associated injuries. Modeling of the 1991 injury cohort from a major Michigan compensation insurer

STUDY DESIGN

A retrospective cohort of 2425 workers with compensated back conditions was created from the 1991 compensated cohort of the largest compensation insurer in Michigan by linking computerized information on social and demographic factors, diagnostic and management procedures, and cumulative missed worktime.

OBJECTIVE

To describe medical care use from date of injury in 1991 to mid-1993 by type of back condition, to identify factors affecting this use, to determine the effect of alternative model selection strategies on identifying such factors, to investigate the timing of surgery and the use of diagnostic studies in patients with displaced or herniated discs with and without surgery, and to compare the use of medical care in the study group with that recommended by national expert panels.

SUMMARY OF BACKGROUND DATA

Despite the enormous costs involved in medical care for patients with work-related back injuries, almost no information on the use of medical care is available for compensated back injuries by diagnostic and procedure code.

METHODS

Use of medical care was grouped into 18 categories for tabulation. Factors affecting use of medical care were identified by logistic regression, supplemented by Cox analysis for time to first procedure. The Hosmer-Lemeshow chi-square statistic was compared with the Bayes Information Criterion for evaluating model fit. Overall model utility was evaluated by comparing receiver operating characteristic curves generated by the model. For patients with displaced or herniated discs, algorithms were used to identify the diagnostic procedures performed before and after the first surgery and the amount of time that passed before each procedure was performed.

RESULTS

In patients with diagnoses of disc displacement or herniation or vertebrogenic neuritis, approximately 80% underwent radiography to obtain plain views of the spine, 75% underwent diagnostic imaging, 45% underwent electrodiagnostic procedures, and 24% underwent spinal surgery (29.3% had surgical procedures among those with disc conditions). In patients with diagnoses of back sprain or other symptomatic diagnoses, the percentages for the first three procedures are approximately 70%, 12%, and 12%, respectively. Diagnostic category, age, gender, and cumulative missed worktime predicted the receipt of diagnostic and treatment procedures. Women were 30% less likely to undergo computed axial tomography or magnetic resonance imaging and 50% less likely to undergo spinal surgery. Median time to spinal surgery was twice as long in the group that underwent diagnostic imaging and electrodiagnostic testing before surgery (134.5 days). Of the 622 patients with disc displacement/herniation, 510 (approximately 80%) had initial diagnostic imaging studies, and, of the 510, 162 (approximately 30%) had surgery. Thirteen (8%) were reoperated. Of the 162 patients who had surgery, 46 (approximately 30%) had follow-up diagnostic imaging, and, of the 46, nine (approximately 20%) were reoperated. Of the 348 managed conservatively, 96 (approximately 30%) had follow-up diagnostic imaging.

CONCLUSIONS

The data suggest only modest differences in the use of medical care between this study group and noncompensated study populations from previous reports. The authors of this study estimate that 27% of diagnostic imaging studies and 43% of plain radiography of the spine could have been avoided if then available Canadian recommendations or current American, guidelines had been followed. The gender effect remains unexplained and needs to be investigated in additional studies. There was an increase of 6% in the use of surgery in compensated patients compared with the use of surgery in a recent American series involving traditional health insurance, but this may be associated with greater work disability in the compensated group. The results of the current study suggest that the use and reporting of model selection strategies and the use of receiver operati

Extension of receiver operating characteristic analysis to data concerning multiple signal detection tasks

RATIONALE AND OBJECTIVES

When receiver operating characteristic (ROC) studies involve multiple detection tasks in the same patient, the correlations among the within-patient interpretations and the shortage of patients raise several analytic challenges. The authors propose methods for both parametric and nonparametric analysis of this type of data.

METHODS

First, they computed one accuracy statistic for each task. Then one jackknife "pseudovalue" was calculated for each task and each patient. Then, they formed a summary index from the accuracy statistics and calculated the standard error of this summary index on the basis of the observed correlations among the jackknife pseudovalues. The method was extended to comparisons of two diagnostic systems and illustrated by using data from a clinical study.

RESULTS AND CONCLUSION

This approach can be used with rating or quantitative data and with any index of accuracy, whether calculated parametrically or nonparametrically.