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PubMed2001

Non-penetrating glaucoma surgery using AquaFlow(TM)collagen implants.

AquaFlow TM is an absorbable collagen implant for use in non-penetrating surgery for primary open angle glaucoma. Its purpose is to facilitate drainage of fluid from the eye, thereby reducing intraocular pressure. AquaFlow TM is approved for use in Canada in medically refractory cases of primary open angle glaucoma. Non-penetrating glaucoma surgery with the AquaFlow TM implant appears to be a relatively safe procedure. However, there is a steep learning curve for the surgeon and it is initially associated with a high rate of conversion to conventional surgery during the operation. Limited evidence from small non-randomized trials suggests that the AquaFlow TM implant may offer benefits over conventional surgical approaches in terms of reduced complication rates, reduced medication use, an earlier return of improved vision and sustained control of intraocular pressure. However, the efficacy and cost-effectiveness of this approach have not been established. January, 2001 for use in patients with uncontrolled

Canada↗
PubMed2004

Changing treatment patterns for coronary artery revascularization in Canada: the projected impact of drug eluting stents.

BACKGROUND: To evaluate current treatment patterns for coronary artery revascularization in Canada and explore the potential impact of drug eluting stents (DES) on these treatment patterns. METHODS: Eleven cardiologists at multiple Canadian academic centers completed a questionnaire on coronary artery revascularization rates and treatment patterns. RESULTS: Participating physicians indicated slightly higher rates of PTCA, CABG, and stent implantation than reported in CCN publications. Participants estimated that 24% of all patients currently receiving bare metal stents (BMS) would receive DES in the first year following DES approval in Canada, although there was a large range of estimates around this value (5% to 65%). By the fifth year following DES approval, it was estimated that 85% of BMS patients would instead receive DES. Among diabetic patients, estimates ranged from 43% in the first year following approval to 91% in the fifth year. For all patients currently receiving CABG, mean use of DES instead was estimated at 12% in the first year to 42% at five years; rates among diabetic patients currently undergoing CABG were 17% in the first year to 49% in the fifth year. CONCLUSIONS: These results suggest a continued increase in revascularization procedures in Canada. Based on the panel's responses, it is likely that a trend away from CABG towards PTCA will continue in Canada, and will be augmented by the availability of DES as a treatment option. The availability of DES as a treatment option in Canada may change the threshold at which revascularization procedures are considered.

Adult↗
PubMed2005

Surgical technique of lumbar artificial disc replacement with the Charité artificial disc.

Lumbar artificial disc technology has been commercially available outside the United States for nearly 2 decades. With the Food and Drug Administration approval of the Charité Artificial Disc in October 2004, an entirely new spinal surgeon population will be able to offer this technology to their patients as a treatment option. As with other techniques in spinal surgery, indications for lumbar total disc replacement are paramount to the success of the procedure. The correct surgical technique is also important to a successful outcome. This article describes the technique for placement of the Charité Artificial Disc in indicated patients. The technique is similar to that of an anterior lumbar interbody fusion procedure, but many differences between the techniques make lumbar total disc replacement a unique procedure in the spinal surgeon's armamentarium. Although this article is thorough in its description of the surgical technique for total disc replacement with the Charité Artificial Disc, it should not be used as a substitute for company-sponsored training.

Device Approval↗
PubMed2003

Device therapy for heart failure.

Although pharmacologic therapy has made impressive advances in the past decade and is the mainstay of therapy for heart failure (HF), there is still a large unmet need, because morbidity and mortality remain unacceptably high. Implanted medical devices are gaining increasing utility in this group of patients and have the potential to revolutionize the treatment of HF. The majority of devices in clinical use or under active investigation in HF can be grouped into 1 of 4 categories: devices to monitor the HF condition, devices to treat rhythm disturbances, devices to improve the mechanical efficiency of the heart, and devices to replace part or all of the heart's function. There are several devices either approved or under development to monitor the HF condition, ranging from interactive weight scales to implantable continuous pressure monitors. The challenge is to demonstrate that this technology can improve patient outcomes. Pacemakers and implantable cardioverter defibrillators (ICDs) are used to treat heart rhythms in a broad range of patients with heart disease, but they now have a special place in HF management with the prophylactic use of ICDs in patients who have advanced systolic dysfunction. The Multicenter Automatic Defibrillator Implantation Trial (MADIT) II study demonstrated a 29% reduction in all-cause mortality with ICDs in patients with a history of a myocardial infarction and a left ventricular (LV) ejection fraction <0.30. LV and multisite pacing are means of improving the mechanical efficiency of the heart. The concept is to create a more coordinated contraction of the ventricles to overcome the inefficiency associated with conduction system delays, which are common in HF. The acute hemodynamic effect can be impressive and is immediate. Several studies of intermediate duration (3 to 6 months) have consistently demonstrated that biventricular pacing improves symptoms and exercise capacity. Mechanical methods of remodeling the heart into a more efficient shape have been under scrutiny for several years. New methods of restraining the heart with prosthetic material are under investigation in humans, with encouraging pilot results. Heart replacement has been evaluated clinically with LV assist devices for several decades. The Randomized Evaluation of Mechanical Assistance Therapy as an Alternative in Congestive Heart Failure (REMATCH) study has demonstrated a proof of concept for the use of mechanical blood pumps to improve survival, functional capacity, and symptoms. Several assist devices with such features as total implantability, improved durability, and smaller size are now under study; these may further improve the outcomes of patients. One year ago, the world witnessed the first clinical use of a totally implantable total artificial heart. Although the long-term outcomes were limited, the device demonstrated an impressive ability to improve organ function and extend survival in the population facing imminent death. Further development in this field is expected. The use of devices in HF now has a strong foothold, and the potential exists for substantially greater use of a broad range of devices in the near future.

Clinical Trials as Topic↗
PubMed2004

Exploring options for improving healthcare.

New medical technologies generally must receive clearance or approval for marketing by the US Food and Drug Administration and be covered by an insurer, such as the Centers for Medicare and Medicaid Services, before becoming available for widespread clinical use. These 2 approval processes are discrete and usually occur sequentially rather than collaboratively and simultaneously. To explore potential mechanisms for increasing regulatory collaboration between these 2 key health care agencies, the Duke Clinical Research Institute and Health Strategies Consultancy convened an informal meeting of agency, academic, and industry leaders on December 8 and 9, 2002, titled "Registration/Approval and Coverage/Payment: Exploring Options for Improving Healthcare." This article arises from the discussion at this conference; it does not represent the official views of any person or institution involved. Although the group did not attempt to reach a consensus, it examined several important issues surrounding this regulatory debate. Herein are proposed options for enhancing regulatory efficiency through greater coordination between the FDA and CMS, and discussion of these proposals from the perspectives of members of both agencies, members of stakeholder organizations, and academic observers.

Biomedical Technology↗
PubMed2003

Considerations for the planning and conduct of reproducibility studies of in vitro diagnostic tests for infectious agents.

The US Food and Drug Administration (FDA) requires reproducibility studies for premarket approval of in vitro diagnostic (IVD) tests. Results of reproducibility studies provide an estimate of the variability of the IVD test among study sites, reagent lots, site operators, within a single test run, and over multiple test days. In planning the study, discuss the product registration strategy, including the intended use of the product and desired label claims, and define the study team. Design the sample panel according to the limit of detection or quantitation of the test, dynamic range of the test, FDA guidelines, sample matrix, and genotype. Consider legal and ethical issues for obtaining the panel parent specimen, such as minimizing the privacy risk and keeping promises to donors. During the study, review data promptly to determine invalid runs, discover trends in the data that may require additional operator training, ensure correct completion of case report forms, and resolve queries quickly. At the end of the study, gather the study team to review and improve processes. Use the outcome to set expectations of other functional areas and to provide product feedback.

Benchmarking↗
PubMed2005

New intraocular lens technology.

PURPOSE: To review the current status of phakic intraocular lenses (IOLs), intraocular treatment of presbyopia, and IOLs that filter some blue light. DESIGN: Review of current information on the subject from numerous sources. METHODS: Medline search and Internet search engines on the topics of phakic IOLs, presbyopia or multifocal IOLs, and blue light and macular degeneration. RESULTS: An iris fixated phakic IOLs is now approved in the United States (US). There are concerns for corneal endothelial stability and late dislocation. Other approaches include anterior chamber fixation with concerns of corneal endothelial stability and pupil elongation, and posterior chamber fixation with concerns of cataract formation, IOL dislocation, and pigment dispersion. Intraocular treatment of presbyopia includes monovision, multifocal, and accommodative IOLs. Which approach is superior today is still not clear. There are IOLs designed to block some blue light to potentially lessen the risk of age-related macular degeneration (ARMD). While there is presumptive evidence of this, no definitive study shows such a correlation. Color perception issues are unlikely to be a problem. While decreased scotopic vision has been proposed, there is no study that proves this is an issue of clinical significance. CONCLUSIONS: The IOL field is dynamic with many new choices. Phakic IOLs and treatment of presbyopia will be an increasingly important part of ophthalmology; however, there are important unresolved issues. With better evidence that blue light is an important variable in ARMD, such an approach could rapidly become the standard.

Biomedical Technology↗
PubMed1999

[Vena cava filter for prevention of pulmonary embolism].

Vena caval filters in the prevention of pulmonary embolism All currently available caval filters can be implanted percutaneously in local anaesthesia. In the USA the FDA has approved the stainless steel Greenfield filter, the Titanium Greenfield filter, the Bird's Nest filter, the LGM or VenaTech filter and the Simon Nitinol filter. Some other caval filters are commercially available in Europe, but there exist only few clinical trials about them. The Greenfield filter is implanted since the early seventies and the greatest amount of data has been published about it. Standard indications for filter placement are recurrent pulmonary embolism despite adequate anticoagulation, in patients after pulmonary embolectomy, when there is a contraindication to anticoagulation (e.g. fresh surgical wound, active gastrointestinal bleeding, recent haemorrhagic stroke, major trauma,...) and when serious complications occur after thrombolysis or anticoagulation. In patients who suffer from severe cardiopulmonary disease both a caval filter and anticoagulation may be required. Follow-up investigations include plain abdominal radiography and duplex ultrasound, in special cases computed tomography, cavography, magnetic resonance imaging in newer filter types, and intravascular ultrasound. Complications include recurrent pulmonary embolism, caval obstruction, migration, fracture and perforation of filter struts. As clinically relevant complications are rare, in diligently selected cases the patient will benefit from implantation of a caval filter.

Device Approval↗
PubMed1994

Peripheral atherectomy with the rotablator: a multicenter report. The Collaborative Rotablator Atherectomy Group (CRAG).

PURPOSE: Our purpose was to evaluate the efficacy and limitations of the Auth Rotablator, an atherectomy device recently approved by the U.S. Food and Drug Administration for general use in treating peripheral arterial occlusive lesions. METHODS: Between August 1987 and December 1990, 72 patients from three medical centers (University of California, Los Angeles, Montefiore, and Stanford) underwent atherectomy with the Auth Rotablator in 79 limbs and 107 arteries: 2 iliac, 45 femoral, 29 popliteal, and 31 tibial. The average age among the 72 patients was 69 years (43 to 91 years), and 67% were men. Indications for atherectomy were claudication in 34 (43%), limb threat in 44 (56%), and asymptomatic in 1 (1%) case. Average ankle-brachial index was 0.47 (0 to 0.81). Average length of lesions was 9 cm (1 to 40 cm); 70 treated arterial segments were less than 10 cm and 37 were greater than 10 cm. All patients underwent arterial pulse examination, vascular laboratory Doppler measurement of ankle-brachial indexes, and arteriography before and after surgery and at follow-up intervals during a period of 15 to 41 months (mean 27 months). RESULTS: Angiographic success (residual lumen < 25% stenosis) was achieved in 70 (89%) of 79 limbs and 82 (77%) of 107 arteries: iliac 1 (50%) of 2, femoral 38 (84%) of 45, popliteal 24 (83%) of 29, and tibial 19 (61%) of 31. In-hospital clinical and hemodynamic success was achieved in 61 (77%) of 79 limbs. The cumulative primary patency rate was 47% at 6 months, 31% at 12 months, and 18.6% at 24 months. Complications included hemoglobinuria in 10 cases (13%), emboli in eight cases (10%), dissection in five cases (6%), perforation in three cases (4%), hematoma in four cases (5%), and infection in one case (1%). There were nine early thromboses (11%) and two device-related amputations (2.5%). CONCLUSION: Peripheral atherectomy with the Auth Rotablator currently has limited application because of frequent early thromboembolic complications and poor late patency rates. Atherectomy is not generally recommended for treating peripheral arterial occlusive lesions until these problems with early thromboemboli, occlusions, and late restenoses are solved.

Adult↗
PubMedDate not supplied

[Drug distribution systems in hospitals].

Any drug generally made and marketed by drug companies must respect the quality standards conferred by New Drug Approval regarding both safety and efficacy. Once prescribed by a doctor, inside a hospital, the drug, or more precisely the decision of its prescription will follow a complex circuit, involving numerous intermediates (human and technical) leading to drug dispensation and follow-up. Regulatory guidelines and rules harmonise and standardise this drug pathway in hospitals. Any weakness in this distribution system will be the source of nosocomial drug iatrogeny. The present review aims at describing the different steps and stages from the prescription to an individual patient to drug administration and follow-up. The evaluation of this system will be mentioned in the perspective of optimisation. The computerised system is essential allowing tracking of a drug, and providing help for decision-making (by confrontation with data bases) and a research tool (i.e, pharmacoepidemiology). Different experiences of assessment of the performance of such a drug distribution system inside hospitals will be presented, trying to check the quality reference: the right drug, the right patient, the right moment, in good conditions. The challenge is to optimise and secure all steps of the process. This goal needs assessment and quality control of the different phases, opening the discussion between hospital policy and regulatory and technical considerations.

Device Approval↗
PubMed2002

Hemodynamic stability during 17 years of the Carpentier-Edwards aortic pericardial bioprosthesis.

BACKGROUND: Long-term stability of the hemodynamic performance of commercially available Carpentier-Edwards stented bovine pericardial aortic bioprostheses (Perimount RSR) is unknown. To anticipate the fate of this bioprosthesis, we examined its hemodynamic performance up to 17 years using echocardiographic studies in a Premarket Approval cohort. METHODS: Of 267 patients at four institutions in the Premarket Approval cohort, 85 had a total of 168 echocardiographic studies during a 17-year period of yearly follow-up examinations. These were reviewed and quantified in a core echocardiographic facility. Longitudinal data analysis was used to account for repeated, censored data. RESULTS: Mean transvalvular gradient was inversely related to prosthesis size (p = 0.01), and possibly (p = 0.06) increased somewhat during the first 10 years of follow-up, then stabilized. Effective orifice area was larger in larger valve sizes (p = 0.01), declined somewhat during the first 10 years, and then began to increase again. Ejection fraction declined minimally (p = 0.2). In contrast to the rather stable hemodynamics, aortic regurgitation steadily increased from none to 1 to 2+ (p = 0.005), but rarely (< 10% at 17 years) progressed to 3+ or 4+. CONCLUSIONS: The Carpentier-Edwards aortic pericardial bioprosthesis can be anticipated to have an acceptable long-term transvalvular gradient and effective orifice size that will change trivially up to 17 years after implantation. Mild aortic regurgitation will develop progressively. This anticipated hemodynamic resilience supports continued clinical use of the Perimount Carpentier-Edwards bovine pericardial stented bioprosthesis.

Adult↗
PubMed2006

Rapid HIV testing at home: does it solve a problem or create one?

The U.S. Food and Drug Administration (FDA) is considering approval of an over-the-counter, rapid HIV test for home use. To date, testimony presented before the FDA has been overwhelmingly supportive. Advocates have argued enthusiastically that there is value in empowering individuals to manage their HIV risks and have suggested that the availability of a rapid home HIV test will dramatically increase rates of disease detection in communities that have proven difficult to reach and to link to appropriate care. The authors offer a more cautious perspective. According to what is already known about the market demand for over-the-counter HIV testing kits, their costs, and the performance of rapid HIV tests in that market, the authors do not anticipate that the rapid home test will have a profound impact either on the HIV public health crisis or on the populations in greatest need. Home HIV testing will attract a predominantly affluent clientele, composed disproportionately of HIV-uninfected new couples and "worried well" persons, as well as very recently infected persons with undetectable disease. The authors illustrate how testing in these populations may have the perverse effect of increasing both false-positive and false-negative results. A poorly functioning home HIV test may thereby undermine confidence in the reliability of HIV testing more generally and weaken critical efforts to expand HIV detection and linkage to lifesaving care for the estimated 300,000 U.S. citizens with unidentified HIV infection.

Costs and Cost Analysis↗
PubMed2001

A comparative meta-analysis on the variability in test performance among FDA-licensed enzyme immunosorbent assays for HIV antibody testing.

BACKGROUND: Although independently published studies have compared diagnostic test performance among various manufactured enzyme immunosorbent assays (EIAs) used in HIV antibody testing, none have attempted to formally synthesize such results through a comparative meta-analysis. In particular, no estimates of post-FDA approval test performance, in terms of sensitivity and specificity, and their associated variability within each manufacturer, has been reported in the literature, along with an analysis of the relative differences in manufacturer test performance in practice (after FDA approval). METHODS: Retrieval of studies was done using several searching strategies, while retrieval of manufacturer information was done through package inserts and direct contacts. Comparisons of HIV antibody test performance across manufacturers and within a single manufacturer were made based on 16 estimates (from 11 articles) and 33 estimates (from 19 articles), respectively. A generalized linear model, based upon Bayes estimates of sensitivity and specificity, was used to assess the impact of several study-level covariates on the performance of these EIAs, with overall estimates of manufacturer test performance and associated variability obtained based on generalized estimating equations. RESULTS: Estimates of test performance were obtained across studies, with a significant (P < 0.01) difference between manufacturers. The test performance of each manufacturer significantly interacted (P < 0.05) with the following study-level covariates: type of population screened, year of diagnostic testing and study quality. Among a single manufacturer, Abbott, significant improvement in estimates of test sensitivity (P < 0.01) and specificity (P < 0.01) was observed with each newly produced antibody kit. CONCLUSION: Estimates on the relative differences in test performance within each manufacturer may be used for guiding decisions on the choice of EIA test kit for HIV antibodies, given the type of population screened, as well as cost and time considerations. In addition, the results of this meta-analysis may be used in modeling HIV prevalence when used as prior information within a Bayesian framework or for standardizing test results among various manufacturers.

Bayes Theorem↗
PubMed2005

Towards a medically approved technology for alginate-based microcapsules allowing long-term immunoisolated transplantation.

The concept of encapsulated-cell therapy is very appealing, but in practice a great deal of technology and know-how is needed for the production of long-term functional transplants. Alginate is one of the most promising biomaterials for immunoisolation of allogeneic and xenogeneic cells and tissues (such as Langerhans islets). Although great advances in alginate-based cell encapsulation have been reported, several improvements need to be made before routine clinical applications can be considered. Among these is the production of purified alginates with consistently high transplantation-grade quality. This depends to a great extent on the purity of the input algal source as well as on the development of alginate extraction and purification processes that can be validated. A key engineering challenge in designing immunoisolating alginate-based microcapsules is that of maintaining unimpeded exchange of nutrients, oxygen and therapeutic factors (released by the encapsulated cells), while simultaneously avoiding swelling and subsequent rupture of the microcapsules. This requires the development of efficient, validated and well-documented technology for cross-linking alginates with divalent cations. Clinical applications also require validated technology for long-term cryopreservation of encapsulated cells to maintaining a product inventory in order to meet end-user demands. As shown here these demands could be met by the development of novel, validated technologies for production of transplantation-grade alginate and microcapsule engineering and storage. The advances in alginate-based therapy are demonstrated by transplantation of encapsulated rat and human islet grafts that functioned properly for about 1 year in diabetic mice.

Alginates↗
PubMed2000

Study design in the evaluation of breast cancer imaging technologies.

RATIONALE AND OBJECTIVES: Bringing a new imaging technology to market is a complex process. Beyond conceptualization and proof of concept, obtaining U.S. Food and Drug Administration (FDA) approval for clinical use depends on the documented experimental establishment of safety and efficacy. In turn, safety and efficacy are evaluated in the context of the intended use of the technology. The purpose of this study was to examine a conceptual framework for technology development and evaluation, focusing on new breast imaging technologies as a highly visible and current case in point. MATERIALS AND METHODS: The FDA views technology development in terms of a preclinical and four clinical phases of assessment. With a concept of research and development as a learning model, this phased-assessment concept of regulatory review against intended use was integrated with a five-level version of a hierarchy-of-efficacy framework for evaluating imaging technologies. Study design and analysis issues are presented in this context, as are approaches to supporting expanded clinical indications and new intended uses after a new technology is marketed. CONCLUSION: Breast imaging technologies may be intended for use as replacements for standard-of-care technologies, as adjuncts, or as complementary technologies. Study designs must be appropriate to establish claims of superiority or equivalence to the standard for the intended use. Screening technologies are ultimately judged on their demonstrated effectiveness in decreasing cause-specific mortality through early detection, but they may be brought to market for other uses on the basis of lesser standards of efficacy (eg, sensitivity, specificity, positive and negative predictive value, and stage of disease detected).

Breast Neoplasms↗
PubMed2005

The incidence of microbial keratitis among wearers of a 30-day silicone hydrogel extended-wear contact lens.

PURPOSE: To estimate the incidence of presumed microbial keratitis with and without loss of visual acuity among wearers of a silicone hydrogel contact lens (Lotrafilcon A, Night & Day, CIBA Vision, Inc., Duluth, GA), recently approved for up to 30 days of continuous wear. DESIGN: Prospective cohort postmarket surveillance study. PARTICIPANTS: Contact lens wearers (recruited from 131 practices) who had been prescribed the lens for intended continuous wear of as many as 30 nights. METHODS: The occurrence of a corneal infiltrate was ascertained through a combination of center report and direct contact with participants at 3 and 12 months. Whenever a corneal infiltrate was suspected, study and treatment medical records were systematically reviewed by an Endpoints Committee using a predetermined classification scheme for corneal infiltration. Cases of presumed microbial keratitis were determined based on the constellation of presenting signs and symptoms and clinical course. MAIN OUTCOME MEASURES: The incidence of presumed microbial keratitis with and without loss of visual acuity. RESULTS: A total of 6245 participants were recruited between August 13, 2002 and July 2, 2003. Of these, 4999 subjects (80%) completed 12 months of follow-up, and these participants contributed a total of 5561 person years of lens wearing experience. Approximately 80% of participants routinely wore their lenses continuously for 3 or more weeks. The overall annual rate of presumed microbial keratitis was 18 per 10,000 (95% confidence interval (CI): 8.5-33.1). There were 2 cases of presumed microbial keratitis with loss of visual acuity, an annual rate of 3.6 per 10,000 (95% CI: 0.4-12.9), and an additional 8 cases without loss of visual acuity, an annual rate of 14.4 per 10000 (95% CI: 6.1-28.4). The rate of presumed microbial keratitis was lower for users reporting typical wear of 3 or more weeks than for those wearing the lens for less than a 3-week continuous period (P = 0.02). CONCLUSIONS: The incidence of loss of visual acuity due to microbial keratitis among users of the silicone hydrogel contact lens was low. The overall rate of presumed microbial keratitis with the wearing schedule of as many as 30 nights was similar to that previously reported for conventional extended-wear soft lenses worn for fewer consecutive nights.

Adolescent↗