Concentration of hospital care for acute sickle cell disease-related visits.

BACKGROUND: Sickle cell disease (SCD) is characterized by frequent disease-related events that require acute care. It is unknown to what extent patients utilize multiple hospitals for acute care. We examined the continuity pattern of acute care visits to the hospital or emergency department. We hypothesized that among patients with multiple SCD related acute care visits, children experience more concentrated hospital care than adults and privately insured patients experience more concentrated hospital care than publicly insured patients. PROCEDURE: We conducted a retrospective cohort study using data from the 2005 and 2006 Healthcare Cost and Utilization Project State Inpatient Databases and State Emergency Department Databases. Subjects included patients with SCD ≥ 1 year of age. The primary outcome was proportion of patients with multiple acute care visits to a single hospital. RESULTS: A total of 13,533 patients made ≥ 2 acute SCD-related visits. Of the 5,030 children, 77.3% went to the same hospital for all visits. In contrast, of the 8,503 adults, only 51.3% visited the same hospital. Adolescents were more likely than adults to go to one hospital [adjusted relative risk (ARR) 1.40, confidence interval (CI) 1.35-1.45]. Those with public insurance and the uninsured had a decreased probability of using one hospital (ARR 0.96, CI 0.94-0.99, and ARR 0.83, CI 0.79-0.88, respectively). CONCLUSIONS: Adults and patients with public insurance or no insurance are more likely to use multiple hospitals for acute care. By receiving acute care at multiple hospitals, patients with SCD experience dispersed and fragmented care potentially leading to decreased care quality.

Completeness of cause of injury coding in healthcare administrative databases in the United States, 2001.

OBJECTIVES: To determine the completeness of external cause of injury coding (E-coding) within healthcare administrative databases in the United States and to identify factors that contribute to variations in E-code reporting across states. DESIGN: Cross sectional analysis of the 2001 Healthcare Cost and Utilization Project (HCUP), including 33 State Inpatient Databases (SID), a Nationwide Inpatient Sample (NIS), and nine State Emergency Department Databases (SEDD). To assess state reporting practices, structured telephone interviews were conducted with the data organizations that participate in HCUP. RESULTS: The percent of injury records with an injury E-code was 86% in HCUP's nationally representative database, the NIS. For the 33 states represented in the SID, completeness averaged 87%, with more than half of the states reporting E-codes on at least 90% of injuries. In the nine states also represented in the SEDD, completeness averaged 93%. Twenty two states had mandates for E-code reporting, but only eight had provisions for enforcing the mandates. These eight states had the highest rates of E-code completeness. CONCLUSIONS: E-code reporting in administrative databases is relatively complete, but there is significant variation in completeness across the states. States with mandates for the collection of E-codes and with a mechanism to enforce those mandates had the highest rates of E-code reporting. Nine statewide ED data systems demonstrate consistently high E-coding completeness.

Relation between prepublication release of clinical trial results and the practice of carotid endarterectomy.

CONTEXT: Little is known about how clinical practice is affected by disseminating results of clinical trials prior to publication in peer-reviewed journals. OBJECTIVE: To determine whether prepublication release of carotid endarterectomy (CEA) trial results via National Institutes of Health Clinical Alerts was associated with prompt changes in patient care that were consistent with the new medical evidence. DESIGN, SETTING, AND PATIENTS: Longitudinal data series analysis using acute care hospital discharge data from the Healthcare Cost and Utilization Project for patients who had CEA performed in acute care hospitals in 7 states (New York, California, Pennsylvania, Florida, Colorado, Illinois, and Wisconsin). The trials were the North American Symptomatic Carotid Endarterectomy Trial (NASCET clinical alert released February 1991) and the Asymptomatic Carotid Atherosclerosis Study (ACAS clinical alert released September 1994). MAIN OUTCOME MEASURE: Carotid endarterectomy rate during each month from 1989 (2 years before the NASCET clinical alert) to 1996 (2 years after the ACAS clinical alert), adjusted for age and sex. Because both trials were limited to patients 80 years or younger in hospitals with low mortality, we also stratified CEA rates by patient age and hospital mortality rate. RESULTS: From 1989 through 1996, 272849 CEAs were performed in the acute care hospitals in these 7 states, with the annual number increasing from 22300 to 51 495. Afterthe NASCET clinical alert, the adjusted CEA rate increased 3.4% per month (95% confidence interval [CI], 1.6%-5.3%) during the following 6 months and then increased 0.5% per month (95% CI, 0.2%-0.8%; P<.04) after journal publication of the NASCET study. After the ACAS clinical alert, the CEA rate increased 7.3 % per month (95% CI, 6.0%-8.5%) during the following 7 months and then decreased by 0.44% per month (95% CI, -0.86% to -0.0002%; P<.04) after journal publication of the ACAS study. After the ACAS clinical alert, the CEA rate increased more in patients aged 80 years or older than in younger patients; whereas, after journal publication of ACAS, the CEA rate decreased more rapidly in the older population. The overall proportion of CEAs performed in low-mortality hospitals did not change substantially after release of the clinical alerts or after journal publication. CONCLUSION: In this study, prepublication dissemination of CEA trial results with clinical alerts was associated with prompt and substantial changes in medical practice, but the observed changes suggest that the results were extrapolated to patients and settings not directly supported by the trials.

A two-phase model for controlled drug release from biphasic polymer hydrogels.

A comprehensive two phase model is developed to describe the sustained release of a solute or drug from a biphasic hydrogel substrate. Such a material consists of a continuous hydrophilic phase (polymer backbone in water) and a dispersion of spherical microdomains made of the hydrophobic side chains of the polymer organised in a micelle like fashion. The solute or drug is assumed to be encapsulated within the dispersed microdomains, and to diffuse from the interior to the surface of the microdomain where it exchanges following a Langmuir isotherm. Mass transfer to the bulk phase occurs by desorption of the drug from the surface through a driving force that is proportional to the difference of surface and bulk concentration. Accordingly the drug is released to the surroundings by diffusion through the bulk. Depending on the values of the Langmuir constant and assuming well stirred behaviour in the interior of the microdomain, the present model results in either of the two asymptotic models developed in previous studies. The results of a parametric study show that the desired steady state flux of a specific drug to the surroundings may be obtained given appropriate values of structural properties of the material. This conclusion is further supported when using this model to simulate earlier experimental results. The polymer structural properties can be manipulated easily during the fabrication of dispersed-phase networks, as indicated by preliminary experiments.

Abdominal hysterectomy practice patterns in the United States.

OBJECTIVE: To describe nationwide practice trends for two principal techniques of abdominal hysterectomy in the United States, numbers and rates of total (TAH) and supracervical (SCH) hysterectomy were reviewed with charges for each operation. METHODS: Practice patterns for all inpatient TAH and SCH discharges in the US from 1991 to 1994 were studied using HCUP-3 NIS, a nationwide hospital discharge database. Hysterectomies performed for malignant disease, vaginally or with laparoscopic assistance were not sampled. For each year studied, the number and rate of TAH and SCH, average length of stay (LOS), and mean institutional charge were evaluated. RESULTS: From 1991 to 1994, the US TAH rate (cases/10000 females) decreased significantly from 25.7 to 20.5 (P = 0.02). During the same interval the SCH rate increased significantly from 0.16 to 0.41 (P = 0.04). Nevertheless, TAH accounted for > 99% of all abdominal hysterectomies for each of the 4 years evaluated. The mean institutional charges for the two operations generally depicted SCH to be more costly than TAH. CONCLUSION: The national rates of TAH and SCH rates changed significantly in the United States from 1991 to 1994, with TAH declining and SCH increasing. This mix of cases continues to reflect a strong preference for TAH. Although hospital charges for both procedures increased during this study, these data show that SCH is more expensive than TAH. The much lower utilization of SCH renders nominal its impact on national healthcare expenditures, however. Further studies are needed to assess specific causative factors for these changes in US hysterectomy technique.

[Mumps epidemic in vaccinated children in West Switzerland]. / Studien zur Mumps-Epidemie bei geimpften Kindern in der Westschweiz.

Since 1991, 6 years after the recommendation of universal childhood vaccination against measles, mumps, and rubella (MMR triple vaccine), Switzerland is confronted with a large number of mumps cases affecting both vaccinated and unvaccinated children. Up to 80% of the children suffering from mumps between 1991 and 1995 had previously been vaccinated, the majority with the Rubini vaccine strain. On the basis of a case-control study including 102 patients and 92 controls from the same pediatric population, a study of the humoral immune-response following vaccination with the Rubini vaccine in 6 young adult volunteers, and two different genetic studies, we investigated the complex problem of large scale vaccine failure in Switzerland. We conclude that the recently reported large number of Swiss mumps cases was caused by at least four interacting factors: 1. A vaccine coverage of 90-95% at the age of 2 years is necessary to interrupt mumps wild virus circulation. The nationwide vaccine coverage in Switzerland of some 80% in 27-36 month-old children is too low. 2. Primary vaccine failures (absence of seroconversion or unprotective low levels of neutralizing antibodies), as well as secondary vaccine failures due to the rapid decline of antibodies to mumps virus in our volunteers and controls, seem to be frequent after vaccination with the Rubini strain. 3. Despite its reported Swiss origin, the Rubini strain does not belong to the mumps virus lineages recently circulating in this area but is closely related to American mumps virus strains. 4. Differences in protein structure between the vaccine strain and the circulating wild type strains, and in particular a different neutralization epitope in the hemagglutinin neuraminidase protein, may additionally contribute to the lack of protection in vaccinated individuals.

Technology coverage decisions by health care plans and considerations by medical directors.

OBJECTIVES: Decisions made by private health care plans as to whether to cover new medical technology have a significant impact on access, diffusion, and costs. This study describes the variation in health plan coverage of different laser technologies and the types of considerations used in making coverage decisions for them. METHODS: In a cross-sectional national survey of medical directors at private plans, medical directors indicated current coverage of 15 different laser therapies, and then ranked the top five considerations both in favor and against recommending coverage for three of the laser therapies (angioplasty, discectomy, and photodynamic therapy). The influence of explicit clinical information and/or plan characteristics on coverage and the importance of considerations was examined through multivariate analyses (multiple logistic or linear regression analysis). RESULTS: Overall, 231 medical directors responded from plans representing 66% and 72% of persons in US health maintenance organization and indemnity plans, respectively. Current coverage for 13 of the 15 laser therapies varied between 20% and 90%. For-profit and indemnity plans covered approximately two more of the different laser technologies than nonprofit plans and health maintenance organizations. Considerations most frequently listed in favor of and against recommending coverage across the three laser technologies were clinical, economic, and regulatory. Legal, competitive, and compassionate concerns were listed less frequently. Considerations were not uniform across laser therapies; they reflected the specifics of the technology under review. Plan characteristics influenced the ranking of considerations as well. For instance, health maintenance organizations were two to three times more likely than indemnity plans to list potential for decreased cost in favor of recommending coverage. CONCLUSIONS: These findings demonstrate that there is substantial variation in coverage of new technologies, indicating that a large proportion of the population covered by private health plans are ineligible for treatments that are routinely available to others. A greater range of medical therapy may be available for persons enrolled in indemnity and for-profit plans should their physicians choose to prescribe it. Clinical and economic considerations, including cost-effectiveness, predominate in coverage decisions for new technologies. The importance of considerations appears sensitive not only to specific clinical information, however, but also to characteristics of health plans.

The review process used by US health care plans to evaluate new medical technology for coverage.

OBJECTIVE: To examine the process and information used by medical directors (MDs) of private health plans to make medical coverage determinations for new medical technologies, and to assess the influence of plan characteristics on the process. DESIGN: Cross-sectional national survey. PARTICIPANTS: Two hundred thirty-one MDs at private health plans representing 66% and 72% of the US population covered by HMOs and indemnity plans, respectively. MEASUREMENTS: Actual and optimal review process, final decision authority, sources, and evidence used for technology coverage decisions. RESULTS: In 96% of plans, MDs take part in the medical policy review process for new technology. However, MDs have final authority over coverage decisions in only 27% of plans. Indemnity plans are more likely to assert that MDs should be responsible for final decisions, odds ration (OR) = 3.3 (95% confidence interval [95% CI] 1.4, 10). Optimal sources of information of new technology were journals, medical society statements or practice guidelines, and opinions of national experts. Actual sources of information used differed from optimal ones; local experts were used more often than is considered optimal (p < .001). For-profit plans were more likely than nonprofit plans to use national experts, OR 2.5 (95% CI 1.3, 5.0), and practice guidelines, OR 5.0 (95% CI 2.5, 10). Randomized trials (94% of MDs) meta-analyses (61%), and reviews (42%) were considered the best evidence for making coverage decisions. Barriers to making optimal decisions were lack of timely evidence on effectiveness and cost-effectiveness, not legal or regulatory issues; HMO, small, and nonprofit plans were two or three times more likely to list lack of cost-effectiveness data than their counterparts (p < .05). CONCLUSIONS: Although MDs are nearly always involved in the technology evaluation process, a minority of MDs retain final authority over coverage decisions. Evidence from strong scientific research designs is the most frequently cited basis for decisions, but there is need for more timely, rigorous scientific evidence on medical interventions. How a health plan evaluates a new medical technology for coverage varies with identifiable plan characteristics.

An outbreak of mumps in a population partially vaccinated with the Rubini strain.

Since 1991, 6 years after the recommendation of universal childhood triple vaccination against measles, mumps and rubella (M + M + R), Switzerland has been confronted with an increasing number of mumps cases affecting both vaccinated and unvaccinated children. The M + M + R vaccine mainly used in the Swiss population after 1986 contains the highly attenuated Rubini strain of mumps virus. We analysed an outbreak of 102 suspected mumps cases by virus isolation, determination of IgM antibodies to mumps virus in 27 acute phase sera, and verification of vaccination histories. Mumps was confirmed by virus isolation in 88 patients, of whom 72 had previously received the Rubini vaccine strain. IgM antibodies to mumps virus were detected in 24/27 acute phase serum samples. A group of 92 subjects from the same geographic area without signs of mumps virus infection served as controls. IgG antibodies to mumps virus and vaccination status were assessed in these children. The vaccination rate in these controls was 61%, with equal seropositivity for unvaccinated and Rubini-vaccinated subjects. These data support other recent reports which indicate an insufficient protective efficacy of current mumps vaccines.

Awareness of providers' use of new medical technology among private health care plans in the United States.

In a national survey of medical directors at 231 U.S. private health care plans that cover over two thirds of the privately insured population, we studied whether medical directors are aware when a new technology, such as laser therapy, is being used in procedures for which claims are submitted, the factors alerting them to such use, and the factors prompting them to make a specific coverage decision for the technology. We also examined possible associations between health plans' characteristics (HMO versus indemnity, size, profit status, and time in operation) and their medical directors' awareness of the use of technologies, factors alerting medical directors to their use, and factors prompting specific coverage decisions. The majority of plans were generally not aware that laser technology was being used when it was billed under a general billing code, raising the possibility that less effective or less safe technologies could be introduced rapidly into the treatment of insured populations. Nonprofit and older plans were less likely to be aware that lasers were used in some procedures than for-profit and younger plans.

[A look back at 2 mumps outbreaks]. / Rückblick auf zwei Mumpsausbrüche.

Two studies are presented. The first one concerns a mumps outbreak in a kindergarten in Geneva in June 1991. Of 26 children, nine (34.6%) got mumps. Of nine children vaccinated with the Rubini vaccine strain, seven had the disease as opposed to only one of 14 children vaccinated with the Urabe strain. The vaccine efficacy of the Rubini strain was estimated at 22% with a 95% confidence interval of -10% to 45%. The second study concerns a cluster of 112 mumps patients seen by a pediatrician in the Bernese Jura region between September 1992 and May 1993. A case-control study was carried out resulting in a vaccine efficacy estimate of 50% with a 95% confidence interval of -19% to 81%. Of the cases, 51 (45.5%) had been vaccinated against mumps, 50 of them (98%) with the Rubini vaccine strain. Of the controls, 30 (61.2%) had been vaccinated, 86.7% of them with Rubini. Methodological problems of case selection and their possible effects on the estimated vaccine efficacy are discussed. The results of these two studies have been confirmed by more recent investigations. In retrospect, we therefore conclude that small studies can serve as early indicators for epidemiological evidence and that they can be finally integrated into a more complete picture.

Surgical rates and operative mortality for open and laparoscopic cholecystectomy in Maryland.

BACKGROUND: Since 1989, laparoscopic cholecystectomy has been widely adopted as a treatment for gallstone disease. We analyzed the association between the introduction of this procedure and three variables: the rate at which cholecystectomy was performed in Maryland, the characteristics of patients undergoing cholecystectomy in routine clinical practice, and operative mortality. METHODS AND RESULTS: We used 1985-1992 hospital-discharge data from all 54 acute care hospitals in Maryland, to identify open and laparoscopic cholecystectomies, characteristics of patients undergoing these procedures, and deaths occurring during hospitalizations in which these procedures were performed. The annual rate of cholecystectomy, adjusted for age, rose from 1.69 per 1000 state residents in 1987-1989 to 2.17 per 1000 residents in 1992, an increase of 28 percent (P < 0.001). As compared with patients undergoing open cholecystectomy, patients undergoing laparoscopic cholecystectomy tended to be younger, less likely to have acute cholecystitis or a common-duct stone, and more likely to be white and have private health insurance or belong to a health maintenance organization (P < 0.001). Although the operative mortality associated with laparoscopic cholecystectomy was less than that with open cholecystectomy (adjusted odds ratio, 0.22; 95 percent confidence interval, 0.13 to 0.37) and the overall mortality rate for all cholecystectomies declined from 0.84 percent in 1989 to 0.56 percent in 1992, there was no significant change in the total number of cholecystectomy-related operative deaths because of the increase in the cholecystectomy rate. CONCLUSIONS: In Maryland, although the adoption of laparoscopic cholecystectomy has been accompanied by a 33 percent decrease in overall operative mortality per procedure, the total number of cholecystectomy-related deaths has not fallen because of a 28 percent increase in the total rate of cholecystectomy.

Studies of rheologically active biological macromolecules by quasielastic light scattering.

Variables which describe the structure and rheological behavior of macromolecules in both dilute solutions and gels may be determined using methods of quasielastic laser light scattering (QELS). Such parameters include diffusion coefficients, molecular size such as hydrodynamic radius, and viscoelastic moduli. If the polymer is polydisperse, the distribution of radii may be estimated. Application of the methods is illustrated with data on the size distribution of a tracheal mucin glycoprotein solution as an example of a polydisperse polymer solution of biorheological interest. A scheme for measuring shear moduli of polymer gels using dynamic laser light scattering is illustrated with data on reconstituted fibrin clots.

Effect of Ca++ on the structure and rheology of canine tracheal mucin.

Mucin glycoproteins are known to be the principal determinants of epithelial mucus rheology and hence of mucociliary transport rates. We are studying the structure of such glycoproteins using a model mucin purified from canine tracheal pouch secretions. Of particular interest is the effect on mucin structure of increased Ca++ such as occurs in certain disease states. Quasielastic laser light scattering was used to study the effect of Ca++ on the hydrodynamic radius of the mucin molecules. Scattering data from 0.3mg/ml mucin solutions in physiological phosphate buffer containing 0, 5 X 10(-5)M, and 5 X 10(-4)M Ca++ were analyzed to obtain an average translational diffusion coefficient and the distribution of molecular radii for the dispersion. The effect of Ca++ was to decrease the average Stokes radius. The light scattering results are supported by rheologic measures of mucin gel viscoelasticity.