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Biomedical subjects

J G Jarvik

Publications and source records attributed to J G Jarvik.

At least 19 recordsLinked to original sources
PubMed2002

MR nerve imaging in a prospective cohort of patients with suspected carpal tunnel syndrome.

OBJECTIVES: To evaluate the reliability and diagnostic accuracy of high-resolution MRI of the median nerve in a prospectively assembled cohort of subjects with clinically suspected carpal tunnel syndrome (CTS). METHODS: The authors prospectively identified 120 subjects with clinically suspected CTS from five Seattle-area clinics. All subjects completed a hand-pain diagram and underwent a standardized nerve conduction study (NCS). The reference standard for determining CTS status was a classic or probable hand pain diagram and NCS with a difference >0.3 ms between the 8-cm median and ulnar peak latencies. Readers graded multiple imaging parameters of the MRI on four-point scales. The authors also performed quantitative measurements of both the median nerve and carpal tunnel cross-sectional areas. NCS and MRI were interpreted without knowledge of the other study or the hand pain diagram. RESULTS: Intrareader reliability was substantial to near perfect (kappa = 0.76 to 0.88). Interreader agreement was lower but still substantial (kappa = 0.60 to 0.67). Sensitivity of MRI was greatest for the overall impression of the images (96%) followed by increased median nerve signal (91%); however, specificities were low (33 to 38%). The length of abnormal signal on T2-weighted images was significantly correlated with nerve conduction latency, and median nerve area was larger at the distal radioulnar joint (15.8 vs 11.8 mm(2)) in patients with CTS. A logistic regression model combining these two MR variables had a receiver operating characteristic area under the curve of 0.85. CONCLUSIONS: The reliability of MRI is high but the diagnostic accuracy is only moderate compared with a research-definition reference standard.

Adult↗
PubMed2001

Inpatient costs, length of stay, and mortality for cerebrovascular events in community hospitals.

BACKGROUND: Accurate estimates of inpatient cost, length of stay (LOS), and mortality are necessary for the development of economic models to estimate the cost-effectiveness of stroke-related treatments. Estimates based on data from academic institutions may not be generalizable to community hospitals. In this study, the authors estimated inpatient costs, LOS, and in-hospital mortality for patients with subarachnoid hemorrhage (SAH), intracerebral hemorrhage (ICH), ischemic cerebral infarction (ICI), and TIA who were treated in community hospitals. METHODS: The authors selected patients using International Classification of Diseases-9-Clinical Modification primary diagnosis codes from the HBSI EXPLORE database. They analyzed patient-level data and inpatient costs, derived from detailed utilization data, for all patients admitted to 137 community hospitals in 1998. Multivariate statistical techniques were used to examine patient-, hospital-, and outcome-related factors associated with inpatient costs. RESULTS: Patients with SAH incurred the highest average cost ($23,777, n = 1,124), followed by patients with ICH ($10,241, n = 3,139), ICI ($5,837, n = 18,740), and TIA ($3,350, n = 7,861). Patient subgroups ranked in the same order for average LOS at 11.5 days for SAH, 7.5 days for ICH, 5.9 days for ICI, and 3.4 days for TIA. Almost one third of patients with SAH (29.0%) and ICH (33.1%) died during hospitalization, whereas 7.0% with ICI and 0.2% with TIA died. For each event, as patient age increased, average costs consistently decreased. Also, average costs were higher among patients treated in community teaching hospitals compared to community nonteaching hospitals for each cerebrovascular event (10 to 29%). CONCLUSIONS: Inpatient costs, LOS, and mortality for patients with cerebrovascular disease are dependent on patient and hospital characteristics.

Aged↗
PubMed2001

Don't duck the evidence.

Explore the source record for details and available documents.

Health Knowledge, Attitudes, Practice↗
PubMed2001

Treatment with tissue plasminogen activator and inpatient mortality rates for patients with ischemic stroke treated in community hospitals.

BACKGROUND AND PURPOSE: Most analyses of intravenous tissue plasminogen activator (IV tPA) use for acute stroke in routine practice have been limited by sample size and generally restricted to patients treated in large academic medical facilities. In the present study, we sought to estimate among community hospitals the use of IV tPA and to identify factors associated with the use of IV tPA and inpatient mortality. METHODS: We evaluated a retrospective cohort of 23 058 patients with ischemic stroke from 137 community hospitals. RESULTS: Three hundred sixty-two (1.6%) patients were treated with IV tPA, and 9.9% of those patients died during the hospitalization period. In 35.0% of the hospitals, no patients were treated with IV tPA, whereas 14.6% of hospitals treated approximately 3.0% with IV tPA. After control for multiple factors, younger patients, more severely ill patients (OR 2.02, 95% CI 1.36 to 3.01), and patients treated in rural hospitals (OR 1.80, 95% CI 0.99 to 3.26) were more likely to receive IV tPA, whereas black patients were less likely (OR 0.54, 95% CI 0.31 to 0.95). There also was a trend showing that women were less likely to receive IV tPA (OR 0.84, 95% CI 0.69 to 1.03). Factors associated with an increased odds of inpatient mortality included receipt of IV tPA among men (OR 2.81, 95% CI 1.72 to 4.58) and increased age. Black patients were 27% less likely to die during hospitalization (95% CI 0.60 to 0.90). CONCLUSIONS: In this large, retrospective evaluation of community hospital practice, the use IV tPA and inpatient mortality rates among IV tPA-treated patients were consistent with those of other studies. The likelihood of receiving IV tPA varies by race, age, disease severity, and possibly gender. These factors may influence mortality rates.

Aged↗
PubMed2001

Diagnosis of carpal tunnel syndrome: electrodiagnostic and magnetic resonance imaging evaluation.

In clinically diagnosed CTS without symptoms or signs to suggest other disorders that can mimic CTS, it is unclear whether performing nerve conduction studies are cost-effective. An outcome study to determine whether nerve conduction studies are necessary for the diagnosis may help to clarify this issue. Even less evidence exists regarding the cost-effectiveness of imaging for CTS. MR imaging reliably depicts normal carpal tunnel anatomic details, including the median and ulnar nerves as well as their intraneural fascicular structure. It can also identify pathologic nerve compression and mass lesions that compress nerves such as ganglion cysts. Currently, MR imaging is probably most commonly used to image patients with ambiguous electrodiagnostic studies and clinical examinations. In the near future, MR diffusion-weighted imaging should be possible for peripheral nerves. As is the case with brain imaging, diffusion-weighted imaging of peripheral nerves is likely to be the most sensitive imaging modality for the detection of early nerve dysfunction. Electrodiagnostic studies are likely to remain the pivotal diagnostic examination in patients with suspected CTS for the foreseeable future. With advances in software and hardware, however, high-resolution MR imaging of peripheral nerves should become faster, less expensive, and probably more accurate, possibly paving the way for an expanded role in the diagnosis of this common syndrome.

Carpal Tunnel Syndrome↗
PubMed2000

Imaging of lumbar intervertebral disk degeneration and aging, excluding disk herniations.

With the advent of CT and MR imaging, physicians have been able to complement their clinical diagnosis of the cause of low back pain with a detailed in vivo image of the structure and soft tissues of the spine. At the same time, there has been an increasing realization that information about morphology alone is not enough to make a definitive diagnosis. Proponents of diskography claim that, through pain provocation, it can provide the specificity missing from the purely morphologic information that CT and MR imaging provide. The specificity of diskography, however, is far from clear.

Age Factors↗
PubMed2000

Variation in the quality of lumbar spine MR images in Washington State.

PURPOSE: To investigate the variation in quality of lumbar spine magnetic resonance (MR) images as a function of type of ownership of the imaging center, number of studies performed per month, specialty training of the image interpreter, and field strength of the MR unit. MATERIALS AND METHODS: Data were collected from all imaging facilities in western Washington state that received reimbursement from the Washington State Health Care Authority. Three readers with expertise in spine imaging, who were blinded to center and patient identification information, rated the technical image quality of each study. All MR images of the lumbar spine (maximum of six) paid for by the health care authority were evaluated. If a center had performed more than six studies, then six were randomly selected for evaluation. RESULTS: Variation in quality scores among sites was significant (P =.001). Field strength was the strongest predictor of better quality. Poorer quality was associated with for-profit ownership, a larger number of radiologists at the site reading MR images, and a larger percentage of studies checked by a radiologist prior to the end of the examination. CONCLUSION: There was significant variation in the quality of MR images of the lumbar spine, and at least a portion of this variation was attributable to characteristics of the imaging center.

Ambulatory Care Facilities↗
PubMed2000

MR nerve imaging of the wrist and hand.

Peripheral nerve imaging is still in a relatively early phase of development. This article explains a few of the important technical aspects of peripheral nerve imaging and reviews the results of animal experiments that form the foundation for interpreting image results. The clinical discussion focuses on the use of MR imaging for patients with carpal tunnel syndrome, keeping in mind that many aspects of the imaging technique may be applied to other areas. The reliability, diagnostic accuracy, and potential indications for peripheral nerve imaging are discussed.

Animals↗
PubMed1999

A critical synopsis of the diagnostic and screening radiology outcomes literature.

In summary, the radiology outcomes research literature is both extensive and broad. The methodologic quality, however, is quite variable. Overall, this quality could be improved by intervention in two areas: methodologic dissemination and development. The number of researchers investigating radiology-related outcomes is high, and presently there are over 20 journals devoted exclusively to radiology research. Even with a relatively narrow definition of "outcomes," we identified over 200 radiology outcomes studies, most from the past few years. However, the methodologic quality of most of these articles was relatively low, with important design flaws and biases. Nonetheless, a substantial number of radiology publications do employ state-of-the-art research methods and innovative approaches to methodologic challenges. The quality of radiology outcomes research overall would benefit tremendously from dissemination of such research methods. Instruction in outcomes research methods is accessible to radiologists. For example, there have been several recent articles and series of articles on outcomes research methods in JAMA, including guidelines for the performance and reporting of cost-effectiveness analyses (38-40) and for developing clinical prediction rules (57). Within radiology, several recent articles have appeared on, among other things, cost-effectiveness analysis (34,59,60), assessing quality of life (43), screening for disease (53), and defining the study population (61). The research compendium compiled for the GERRAF (General Electric-Association of University Radiologists Radiology Research Academic Fellowships) program remains a comprehensive methodologic source for many of the issues in radiology outcomes research, and outcomes research methods courses are offered every year at the Society for Health Services Research in Radiology and Society for Medical Decision Making meetings, as well as at the meeting of the Radiological Society of North America. Even so, awareness of the need for such research techniques remains limited. Dissemination of sound research methods is limited at least in part by the current incentives in radiology research. At many institutions, the number of research publications produced, rather than their quality, determines promotion or academic success. Unfortunately, more rigorous study designs often require more time and resources. Further, because peer reviewers are often as uninformed about research methods as the bulk of those who are submitting manuscripts, it may actually be more difficult to publish articles with more advanced methodologic designs. The standard in radiology is the uncontrolled case series, and deviation from the standard may make acceptance for publication more difficult. On a more optimistic note, recent publication of a number of methodology articles suggests that at least some journals are promoting improved research in methodology (43,53,59-61). We hope that time will be available for manuscript reviewers to learn to understand the strengths and weaknesses of various research approaches. If more rigorous study designs were required for publication, radiology outcomes research would probably improve drastically. Nevertheless, the current peer-review system does not effectively promote sound research design. The other great incentive in research is funding. Clearly, if advanced research design is required for funding, then there is incentive for improvement in research quality. Traditionally, National Cancer Institute and other National Institutes of Health and public sector funding has been predicated on a high level of research sophistication. Undoubtedly, availability of grants for diagnostic and screening imaging clinical trials and other research will go far to improve radiology research methods. The other traditional source of research funding is industry.

Case-Control Studies↗
PubMed1999

Health profiles in quality of life: evaluation of diagnostic technologies.

The use of instruments to measure health-related quality of life has become commonplace in medical research, although their use is still unusual in the evaluation of diagnostic technologies. Dr Greenfield has pointed out the potential to abuse as well as use these methods. The cautions that Dr Greenfield has outlined apply to any such research, whether one is evaluating a new drug or a new imaging device. Even though the chain of events from diagnostic technology to patient outcome is longer than for therapeutic interventions, we maintain that quality-of-life instruments are potentially valuable tools for evaluating any of the links in this chain.

Back Pain↗
PubMed1999

Imaging studies for acute low back pain. When and when not to order them.

Acute low back pain is generally a self-limited condition, and most patients recover within a few weeks without the need for imaging studies. However, physicians need to be on the lookout for red flags that point to more serious conditions, such as infection or malignancy, which require imaging. In this article, the authors identify these warning signs and discuss the appropriate use of imaging studies for a variety of symptoms and conditions.

Acute Disease↗
PubMed1999

MR contrast media in neuroimaging: a critical review of the literature.

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.

Cohort Studies↗
PubMed1999

Follow-up of conservatively managed epidural hematomas: implications for timing of repeat CT.

BACKGROUND AND PURPOSE: Small asymptomatic epidural hematomas (EDHs) are frequently managed nonoperatively with good neurologic outcome. Our goals were to determine the frequency and timing of enlargement of acute traumatic EDHs that are not immediately surgically evacuated as well as to identify factors associated with rehemorrhage. METHODS: Of 252 consecutive patients with acute traumatic EDH who were treated over a 5-year period, 160 were managed nonoperatively. Their CT scans, imaging reports, and medical records were reviewed retrospectively. Parameters analyzed as possible predictors of rehemorrhage during nonoperative management were size of the EDH, presence of an associated fracture, contralateral brain injury, midline shift, coagulopathy, and neurologic and physiological injury as measured by the Revised Trauma Score. We compared discharge discharge disposition as a proxy for neurologic condition at discharge. RESULTS: The EDH enlarged in 37 (23%) of the 160 patients during conservative management. Mean enlargement was 7 mm, and the mean time to enlargement was 8 hours after injury and 5.3 hours after CT diagnostics. EDH enlargement occurred within 36 hours after injury in all cases. Of the parameters analyzed, only a high Revised Trauma Score correlated significantly with EDH rehemorrhage, suggesting that intubation and chemical paralysis may prevent rehemorrhage through the restriction of head movement and the control of blood pressure. The subgroup of patients with rehemorrhage experienced no difference in neurologic outcome despite a higher rate of clinical deterioration. CONCLUSION: EDH enlargement occurs frequently, but early. Repeat imaging with CT is most appropriate within 36 hours after injury.

Acute Disease↗
PubMed1997

Rapid MR imaging versus plain radiography in patients with low back pain: initial results of a randomized study.

PURPOSE: To demonstrate the feasibility of a randomized trial to compare rapid magnetic resonance (MR) imaging with plain radiography as the initial imaging study in patients with low back pain, to test measures of the decision-making process and patient outcomes, and to offer a model for using randomized clinical trials to evaluate diagnostic tests. MATERIALS AND METHODS: The authors randomly selected 62 patients with low back pain to undergo either rapid MR imaging or plain radiography. The authors measured functional status, satisfaction, and general health status at baseline and at 3 months. The modified Roland scale was the primary outcome measure. In addition, the authors examined diagnostic and therapeutic decision making and resources used by each group. RESULTS: There were no statistically significant differences between the two patient groups with respect to outcome (Roland score: MR imaging = 12.5, radiography = 12.1). MR imaging provided more useful information to clinicians and resulted in greater patient reassurance. CONCLUSION: Randomly selecting patients to undergo imaging examinations and measuring outcomes is feasible; however, a larger, multicenter study is necessary to determine whether rapid MR imaging is a cost-effective replacement for plain radiography in patients with low back pain.

Adult↗