BACKGROUND AND PURPOSE:MR contrast media are commonly used but do not have evidence-based guidelines for their application. This investigation seeks to define specific methodological problems in the MR contrast media literature and to suggest guidelines for an improved study design.METHODS:To evaluate the reported clinical efficacy of MR contrast media in neuroimaging, we performed a critical review of the literature. From 728 clinical studies retrieved via MEDLINE, we identified 108 articles that evaluated contrast media efficacy for a minimum of 20 patients per study. The articles were randomly assigned to four readers (a fifth reader reviewed all of the articles) who were blinded to article titles, authors, institutions, and journals of publication. The readers applied objective, well-established methodological criteria to assign each article a rating of A, B, C, or D.RESULTS:One hundred one of 108 articles received a D rating, six received a C rating, and one received a B rating. In general, the Methods sections of the evaluated articles did not contain details that would allow the reader to calculate reliable measures of diagnostic accuracy, such as sensitivity and specificity. Specifically, a common problem was failure to establish and uniformly apply an acceptable standard of reference. In addition, images were not always interpreted independently from the reference standard. Radiologists and clinicians need to determine the applicability of any published study to their own practices. Unfortunately, the studies we reviewed commonly lacked clear descriptions of patient demographics, the spectrum of symptomatology, and the procedure for assembling the study cohort. Finally, small sample sizes with inadequate controls were presented in almost all of the articles.CONCLUSION:Although MR contrast media are widely used and play an essential role in lesion detection and confidence of interpretation, no rigorous studies exist to establish valid sensitivity and specificity estimates for their application. On the basis of this review, we herein describe basic methods to document improvements in technology. Such studies are essential to devise measures of diagnostic accuracy, which can form the basis for further studies that will assess diagnostic and therapeutic impact and, ultimately, patient outcomes.

OBJECTIVE:To evaluate a computerized scheduling model that employs nonlinear optimization to recommend optimal follow-up intervals for patients taking warfarin. DESIGN:Randomized trial. SETTING:5 anticoagulation clinics. PATIENTS/PARTICIPANTS:620 patients expected to receive warfarin for > or = 6 weeks. INTERVENTIONS:Computer-generated recommendations for scheduling the next visit were presented to or withheld from practitioners. MEASUREMENTS AND MAIN RESULTS:The main outcome measures were the follow-up interval scheduled by the provider, the interval at which the patient actually returned to clinic, and the quality of anticoagulation control (computed as the absolute difference between the measured and target prothrombin times [PTRs] or international normalized ratios [INRs]). Follow-up intervals scheduled for the patients whose practitioners received computer-generated recommendations were significantly longer than those for control patients (mean, 4.4 vs 3.5 weeks, p < 0.001), despite the fact that the practitioners modified the suggested return interval by > 1 week on 40% of the visits. The interval at which the intervention group actually returned to clinic was also longer (mean, 4.4 vs 4.1 weeks, p < 0.05), even though the control patients tended to return at longer intervals than were scheduled by their practitioners. Control of anticoagulation was nearly the same among experimental and control patients. Life-threatening complications occurred in the care of three experimental patients and one control patient, while other serious complications occurred in the care of 16 experimental patients and 17 control patients. CONCLUSIONS:Recommendations based on nonlinear optimization prompted clinicians to schedule less frequent follow-up for patients taking warfarin, with no deterioration in anticoagulation control. This approach to scheduling can potentially reduce utilization while maintaining quality of care for patients who require long-term monitoring.

New diagnostic tests for the evaluatin of patients with low back pain are constantly emerging, but are often not completely evaluated before they become used. Many published studies have a number of biases that tend to exaggerate the estimated accuracy of a diagnostic test. Several key study design features should be considered in such studies: independent comparison of the diagnostic test results with an appropriate “gold standard”; blinded assessment of the new test and the gold standard or competing tests; the reproducibility of interpretation of the test being examined; and the sensitivity and specificity of the test for the final gold standard diagnosis. In addition, evaluations of test accuracy should include patients with a wide spectrum of illness from mild to severe, and the study setting and patient characteristics should be described in detail. Finally, the contribution of a diagnostic test to the overall validity of a full group or sequence of tests should be considered, and, ideally, the effect of the test on actual patient outcomes should be determined.

PURPOSE:To assess the clinical efficacy of magnetic resonance imaging (MRI) for neuroimaging and to provide guidelines for clinical practice.STUDY SELECTION:After a comprehensive literature search, studies of the diagnostic accuracy of MRI alone or compared with other tests and of any impact on therapeutic choices or patient outcomes were reviewed by independent readers, followed by discussion to reach consensus conclusions.DATA EXTRACTION:Of 3125 citations retrieved, 156 studies with original data could be rated according to methodologic criteria for study design. One article contributed grade A quality information about diagnostic accuracy, 28 were graded B or C, and 113 were graded D. One randomized trial and 2 comparison studies contributed grade B or C information about the impact on therapeutic choices. Only 2 studies surveyed health status before and after magnetic resonance scanning.RESULTS:For most abnormalities, the sensitivity of MRI is equal to or better than competing technologies. Magnetic resonance imaging shows greater contrast and detail than computed tomography (CT) but also shows more clinically silent abnormalities or incidental findings. A few studies found a modest impact on therapeutic choices but no impact on quality of life or disability. Costs for MRI are high. Computed tomography is sufficient for initial diagnosis of most mass lesions or intracranial hemorrhages requiring immediate intervention. Magnetic resonance imaging is more accurate in the temporal lobes, posterior fossa, brainstem, and spinal cord. For lumbar radiculopathy, MRI and plain spinal CT are as accurate as post-myelographic CT and are less invasive. The role of magnetic resonance angiography for carotid artery stenosis is being studied.CONCLUSIONS:Although suggestions for appropriate use of MRI in clinical practice can be made, the supporting evidence in published studies is weak. Firm guidelines for appropriate use of MRI should be based on further clinical research using more rigorous methods.

Letters1 December 1994Magnetic Resonance Imaging of the Brain and SpineDaniel L. Kent, W. T. Longstreth, and David R. HaynorDaniel L. KentSearch for more papers by this author, W. T. LongstrethSearch for more papers by this author, and David R. HaynorSearch for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-121-11-199412010-00019 SectionsAboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail IN RESPONSE:Our comprehensive review [1] made two points. First, suggestions could be made about the selection of imaging tests (see Table 1 of accompanying position paper [2]). Second, the quality of published evidence limited our ability to make stronger recommendations. As a result, users of MRI are vulnerable to both underuse and overuse of a potentially excellent technology. None of those questioning our article actually challenge the College's clinical suggestions, and Dr. Baum's comments support the suggestions given for stroke.The concerns expressed by the authors of the letters may reflect their particular practice backgrounds. Dr. Lossing cites individual ...References1. Kent DL, Haynor DA, Longstreth WL Jr, Larson EB. The clinical efficacy of magnetic resonance imaging in neuroimaging. Ann Intern Med. 1994; 120:856-71. Google Scholar2. American College of Physicians. Magnetic resonance imaging of the brain and spine: a revised statement. Ann Intern Med. 1994; 120:872-5. Google Scholar3. Jensen JC, Brant-Zawadski MN, Obuchowski N, Modic MT, Malkasian D, Ross JS. Magnetic resonance imaging of the lumbar spine in people without back pain. N Engl J Med. 1994; 331:69-73. Google Scholar4. Lindgren A, Roijer A, Rudling O, Norrving B, Larsson EM, Eskilsson J, et al. Cerebral lesions on magnetic resonance imaging, heart disease, and vascular risk factors in subjects without stroke: a population based study. Stroke. 1994; 25:929-34. Google Scholar5. Cowley LT, Isaacs HL, Young SW, Raffin TA. Magnetic resonance imaging marketing and investment: tensions between the forces of business and the practice of medicine. Chest. 1994; 105:920-8. Google Scholar Author, Article, and Disclosure InformationAffiliations: PreviousarticleNextarticle Advertisement FiguresReferencesRelatedDetails Metrics 1 December 1994Volume 121, Issue 11Page: 896-898 ePublished: 15 August 2000 Issue Published: 1 December 1994 Copyright & PermissionsCopyright © 1994 by American College of Physicians. All Rights Reserved.PDF downloadLoading ...

Lack of consensus about the treatment of low back pain is reflected by wide regional variations in lumbar spine surgery rates. Neck pain may be as common as low back pain, but there has been no similar evaluation of regional variation for the surgical treatment of neck pain. This report examines the geographic variation and temporal trends in the rate of cervical spine surgery in Washington state from 1986 through 1989. Using diagnosis and procedure codes from the International Classification of Diseases (ICD-9 CM), the authors retrospectively identified cervical spine surgery cases from a statewide hospital discharge registry for Washington. After excluding cases associated with trauma, infection, or malignancy, 5,173 incident cervical spine surgery cases were analyzed. Cervical spine surgery was performed at approximately 25% the rate of lumbar spine surgery, and from 1986 to 1989, the age- and gender-adjusted rate increased 20%. Small area analysis demonstrated a sevenfold variation among counties in the rate of cervical spine surgery (P < 0.001), with variation of fourfold to 13-fold for specific surgical procedures. These data demonstrate that cervical spine surgery for neck pain is an increasingly common procedure with wide geographic variability. Rational treatment of neck pain requires further definition of indications for cervical spine surgery, preferably based on firm data concerning the outcomes of surgical and nonsurgical care.

Background.-Intravenous (IV) therapy-associated phlebitis is common, but its causes are ill defined. Some cases may be related to bacterial colonization of the skin surrounding the IV catheter, especially by Staphylococcus aureus. This prospective study examined the association of phlebitis with anterior nares S aureus carriage, as well as with other potential risk factors.Methods.-Selected demographic and clinical data and a nares culture were collected from patients on designated wards by us and from the IV therapy team at the time of initial IV catheter placement Patients were followed up for signs and symptoms of phlebitis for the duration of the initial catheter's use and for up to two additional IV placements. Potential risk factors were compared for patients who developed phlebitis and those who did not by the Cox multivariate proportional hazards model.Results.-During 10 weeks, 273 men with a total of 416 catheter placements had fully evaluable data. Phlebitis occurred during 13.7% of the catheter placements. Nasal cultures yielded S aureus from 14.3% of the patients, but none of the IV team nurses. Surprisingly, S aureus nasal colonization was related (at borderline statistical significance) to a reduction in phlebitis risk. Location of the patient on a surgical ward, the presence of infection at any site, and a larger-gauge catheter were each significant independent risk factors for phlebitis. The highest risk of phlebitis appeared to have been within 12 to 24 hours of catheter placement.Conclusions.-The primary finding of this study was that nasal colonization with S aureus did not increase the risk of developing IV catheter-associated phlebitis. Our rate of IV catheter-associated phlebitis was similar to that in other studies, but the factors predisposing to phlebitis differed somewhat from those in previous studies.

We undertook a literature synthesis of CT, MR, and myelographic studies to evaluate what is known about the diagnostic accuracy of these imaging tests for the diagnosis of lumbar spinal stenosis in adults without prior surgery. From 116 possibly relevant studies, we reviewed 14 articles that included cases of spinal stenosis with a reference standard other than the imaging tests of interest. Of the studies we reviewed, two involved only MR, nine only CT, and three used both; six studies included myelography. Rating categories of A, B, C, or D were assigned for the quality of research methods used to estimate diagnostic accuracy. All studies received either a C or D rating. Common methodologic problems were failure to assemble a representative cohort for study, small sample size, and failure to maintain independence between image readings and reference standards. Sensitivity ranged from 0.81 to 0.97 for MR, from 0.70 to 1.0 for CT, and from 0.67 to 0.78 myelography. Studies varied greatly in case selection, definition of test and disease categories, and geographic locale, so no pooled estimates could be derived. In asymptomatic patients, abnormal findings appeared on CT or MR in 4-28% of cases and were more common in the elderly.Published studies of the value of CT and MR for the diagnosis of lumbar stenosis lack methodologic rigor and do not permit strong conclusions about the relative diagnostic accuracies of these procedures. For the present, the choice between MR or CT depends on issues such as costs, reimbursements, access to equipment, skill of radiologists, and patient safety. Better studies will be needed to document claims for improvements in imaging accuracy as MR technologies evolve. These studies should emphasize larger sample sizes, more attention to research designs that avoid methodologic biases, and the contribution of imaging diagnoses to ultimate clinical outcome.

Patients taking warfarin for long-term anticoagulation require frequent clinic visits to monitor the prothrombin time ratio (PTR), a measure of blood clotting. A dynamic stochastic model using nonlinear optimization was developed to select follow-up visit intervals that minimize the overall costs of patient care. Assuming that fluctuations in a patient's PTR behave as a random diffusion process, future PTR fluctuations are unknown, except as revealed by past PTRs. To determine the incidence and costs of complications in relation to PTR, the authors reviewed the charts of 216 patients who had 719 patient-years of follow-up with 695 trivial, significant, life-threatening, or fatal complications. They modeled the relationship between costs of complications and deviation of the PTR from the therapeutic target as a fourth-order convex polynomial. The model is used to compute the interval to the next follow-up visit to minimize accumulated potential costs. Variables in the optimization are the cost of a mon itoring visit and the expected costs of complications. The latter are derived from the current PTR, the variability of the patient's past PTR values, the number of past PTRs available, and the target PTR for the patient. No attempt is made to predict the level of the next PTR or suggest adjustments in the warfarin dose. Shorter follow-up is recommended for patients who have histories of large fluctuations in past PTRs and for patients with few prior PTR determinabons. As visits accumulate, the patient's degree of variability can be estimated more accurately and visit intervals adjusted accordingly The scheduling method balances costs to the health care system of monitoring each patient against the expected costs of complications. This approach has the potential to reduce the number of monitoring visits necessary for safe management of anticoagulated patients with stable PTRs and to improve control among unstable patients. Key words: warfarin; anticoagulation, ambulatory care; follow-up studies; stochastic processes. (Med Decis Making 1992;12:132-141)

BACK pain ranks second only to upper respiratory illness as a symptomatic reason for office visits to physicians.1About 70% of adults have low back pain at some time, but only 14% have an episode that lasts more than 2 weeks. About 1.5% have such episodes with features of sciatica.2,3Most causes of back pain respond to symptomatic and physical measures, but some are surgically remediable and some are systemic diseases (cancer or disseminated infection) requiring specific therapy, so careful diagnostic evaluation is important. Features of the clinical history and physical examination influence not only therapeutic choices but also decisions about diagnostic imaging, laboratory testing, and specialist referral. ANATOMIC/PHYSIOLOGIC ORIGINS OF FINDINGS IN THE LOW BACK Low back pain may arise from several structures in the lumbar spine, including the ligaments that interconnect vertebrae, outer fibers of the annulus fibrosus, facet joints, vertebral periosteum, paravertebral musculature and fascia,

The role of thermography for diagnosing lumbar radiculopathy was evaluated by literature review and meta-analysis. From 81 relevant citations, 28 studies could be analyzed for diagnostic-accuracy data (sensitivity and specificity) and method. Diagnostic-accuracy data varied significantly between studies; therefore meaningful pooled summary statistics could not be reported. Twenty-seven studies had major methodologic flaws including biased test interpretations, faulty cohort assembly, poor clinical descriptions, and small sample size. The only study of reasonably high quality found no discriminant value for liquid-crystal thermography. The role of thermography remains unclear. Rigorous clinical research is required to establish its diagnostic accuracy and clinical utility. Thermography cannot be recommended currently for routine clinical use in evaluating low-back pain.