Comparison of risk adjusters for medicaid-enrolled children with and without chronic health conditions

OBJECTIVE

Several capitation payment systems have been developed and implemented recently by public and private insurers as well as by individual managed care organizations. Many pediatricians have expressed concern that methods for establishing capitation rates may not adequately account for the higher expected expenditures for children with chronic health conditions. In this study, we evaluate a demographic- and 4 diagnosis-based models, paying particular attention to their performance for children with chronic health conditions.

METHODS

We selected children 18 years of age and under who were enrolled in the Maryland Medicaid Program in 1995 and 1996. We defined the population of children with chronic health conditions using ICD-9 codes. Individual and group-level analyses were utilized to measure the ability of the different risk adjustment models to predict expenditures in 1996 based upon information available in 1995.

RESULTS

All 4 diagnosis-based models significantly outperformed the demographic model for children overall and for children with chronic health conditions. Differences between diagnosis-based models were small, especially as the size of test populations increased.

CONCLUSIONS

Risk adjustment methods that account directly for health status promise to reduce incentives to exclude children with chronic illnesses from managed care plans and to provide a foundation for more appropriate payments to pediatricians who care for these children.

Relation between pediatric experience and treatment recommendations for children and adolescents with kidney failure

CONTEXT

Children and adolescent patients with renal failure are frequently cared for by adult subspecialists. While peritoneal dialysis is used in less than 17% of adults with kidney failure, it is the preferred dialysis treatment for children. National data show that 45% of children receiving dialysis are treated with peritoneal dialysis and pediatric nephrologists report its use in 65% of patients receiving dialysis. Whether differences in peritoneal dialysis use among children are due to the pediatric experience of the clinician has not been examined.

OBJECTIVE

To assess whether the pediatric experience of nephrologists directly affects treatment recommendations for children with kidney failure.

DESIGN

Cross-sectional survey using 10 case vignettes per survey based on random combinations of 8 patient characteristics (age, sex, race, distance from facility, cause of renal failure, family structure, education, and compliance).

SETTING AND PARTICIPANTS

National random sample of office-, hospital-, and academic medical center-based adult and pediatric nephrologists, stratified by geographic region and conducted June to November 1999. Of 519 eligible physicians, 316 (61%) responded, including 191 adult and 125 pediatric nephrologists.

MAIN OUTCOME MEASURE

Treatment recommendations for peritoneal dialysis vs hemodialysis, compared based on nephrologists' pediatric experience.

RESULTS

After controlling for patient characteristics, pediatric nephrologists were 60% more likely than adult nephrologists to recommend peritoneal dialysis for identical patients (odds ratio, 1.61; 95% confidence interval, 1.35-1.92). This was true regardless of dialysis training, years in practice, practice setting, geography, or patient characteristics.

CONCLUSIONS

Our data indicate that pediatric specialization of clinicians influences treatment recommendations for children and adolescents with end-stage renal disease. Referring children to adult subspecialists may lead to differences in treatment choices and processes of care.

Infiltration through porous media

We study the kinetics of infiltration in which contaminant particles, which are suspended in a flowing carrier fluid, penetrate a porous medium. The progress of the "invader" particles is impeded by their trapping on active "defender" sites which are on the surfaces of the medium. As the defenders are used up, the invader penetrates further and ultimately breaks through. We study this process in the regime where the particles are much smaller than the pores so that the permeability change due to trapping is negligible. We develop a family of microscopic models of increasing realism to determine the propagation velocity of the invasion front, as well as the shapes of the invader and defender profiles. The predictions of our model agree qualitatively with experimental results on breakthrough times and the time dependence of the invader concentration at the output. Our results also provide practical guidelines for improving the design of deep bed filters in which infiltration is the primary separation mechanism.

U.S. nephrologists' attitudes towards renal transplantation: results from a national survey

BACKGROUND

Renal transplantation is the optimal treatment for persons with end-stage renal disease (ESRD). A shortage of kidneys in the U.S. has focused increasing attention on the process by which kidneys are allocated. A national survey was undertaken to determine the relative importance of both clinical and nonclinical factors in the recommendation for renal transplantation by U.S. nephrologists.

METHODS

We conducted a national random survey of 271 U.S. nephrologists using hypothetical patient scenarios to determine their recommendation for renal transplantation based on demographic, clinical, and social factors. Specifically, eight unique patient scenarios were randomly distributed to each survey respondent.

RESULTS

According to responding nephrologists (response rate 53%), females were less likely than males to be recommended for renal transplantation [adjusted odds ratio (OR)=0.41; confidence interval (CI) 0.21, 0.79; for whites]. Asian males were less likely than white males to be recommended for transplantation (OR=0.46, CI 0.24, 0.91). Black-white differences in rates of recommendation were not found. Other factors associated with low rates of recommendation for renal transplantation included history of noncompliance (OR=0.17, CI 0.13, 0.23), <25% cardiac ejection fraction (OR=0.15, CI 0.10, 0.21), HIV infection (OR=0.01, CI 0.00, 0.01), and being >200 lbs (OR=0.73, CI 0.56, 0.95).

CONCLUSIONS

Female gender, and Asian but not black race, were associated with a decreased likelihood that nephrologists would recommend renal transplantation for patients with end stage renal disease. The well-documented black-white disparities in use of renal transplantation may be due to unaccounted for factors or may arise at a subsequent step in the transplantation process.

Desmin integrates the three-dimensional mechanical properties of muscles

Striated muscle is a linear motor whose properties have been defined in terms of uniaxial structures. The question addressed here is what contribution is made to the properties of this motor by extramyofilament cytoskeletal structures that are not aligned in parallel with the myofilaments. This question arose from observations that transverse loads increase muscle force production in diaphragm but not in the hindlimb muscle, thereby indicating the presence of structures that couple longitudinal and transverse properties of diaphragmatic muscle. Furthermore, we find that the diaphragms of null mutants for the cytoskeletal protein desmin show 1) significant reductions in coupling between the longitudinal and transverse properties, indicating for the first time a role for a specific protein in integrating the three-dimensional mechanical properties of muscle, 2) significant reductions in the stiffness and viscoelasticity of muscle, and 3) significant increases in tetanic force production. Thus desmin serves a complex mechanical function in diaphragm muscle by contributing both to passive stiffness and viscoelasticity and to modulation of active force production in a three-dimensional structural network. Our finding changes the paradigm of force transmission among cells by placing our understanding of the function of the cytoskeleton in the context of the structural and mechanical complexity of muscles.

US nephrologists' recommendation of dialysis modality: results of a national survey

Selection of a dialysis modality for persons with end-stage renal disease (ESRD) has important lifestyle and occupational implications. The factors affecting modality choice remain unclear, resulting in a low rate of peritoneal dialysis (PD) in the United States compared with other countries. A national survey of 271 US nephrologists was conducted from June 1997 to June 1998 to assess the relative importance of nonclinical and clinical factors related to dialysis modality selection for patients with ESRD. Hypothetical patient scenarios were randomly assigned to nephrologists to determine their recommendation for dialytic therapy based on patient demographic, clinical, and social factors. US nephrologists were more likely to recommend PD for men with ESRD compared with women (39% versus 33%; P: < 0.05; adjusted odds ratio, 1.44; 95% confidence interval, 1.15 to 1.80), as well as for patients with good compliance (adjusted odds ratio, 11.80; 95% confidence interval, 9.29 to 15.01), weight less than 200 lb (adjusted odds ratio, 2.3; 95% confidence interval, 1.8 to 2.9), residual renal function (adjusted odds ratio, 2.14; 95% confidence interval, 1.71 to 2.70), absence of diabetes (adjusted odds ratio, 2.0; 95% confidence interval, 1.6 to 2.5), and living with family (adjusted odds ratio, 1.7; 95% confidence interval, 1.4 to 2.1). Nephrologists in practice for 11 or more years were less likely to recommend PD. The association of male sex with PD therapy suggests a potential bias or sensitivity to women's perception of body image. Race was not associated with PD recommendations after controlling for other demographic and clinical characteristics. Because the incident US ESRD population is increasingly characterized by factors associated with not selecting PD (diabetes, obesity, malnourishment, living alone, and substance abuse problems), our results suggest that PD use may decrease over time.

Racial differences in access to the kidney transplant waiting list for children and adolescents with end-stage renal disease

CONTEXT

Renal transplantation is the treatment of choice for pediatric patients with end-stage renal disease (ESRD). Black patients wait longer for kidney transplants than do white patients.

OBJECTIVE

To determine whether the increased time to transplantation for black pediatric patients is attributable not only to a shortage of suitable donor organs, but also to racial differences in the time from a child's first treatment for ESRD until activation on the cadaveric kidney transplant waitlist.

DESIGN

National longitudinal cohort study.

SETTING

US Medicare-eligible, pediatric ESRD population.

PATIENTS

Children and adolescents </=19 years old at the time of their first dialysis for ESRD between 1988 and 1993, followed through 1996. Patients who received living donor renal transplants were excluded from study.

MAIN OUTCOME MEASURES

Time from first dialysis for ESRD until activation on the kidney transplant waiting list, relative hazard of activation on the waiting list for black compared with white pediatric patients.

RESULTS

Comparisons of the time from first dialysis for ESRD to waitlisting among the 2162 white (60.7%) and 1122 black (31.5%) patients studied using survival analysis revealed that blacks were less likely to be waitlisted at any given time in follow-up. In multivariate analysis, even after controlling for patient age, gender, socioeconomic status, geographic region, incident year of renal failure, and cause of ESRD, blacks were 12% less likely to be waitlisted than were whites at any point in time (relative hazard:. 88: 95% confidence interval:.79-.97).

CONCLUSIONS

Racial disparities in access to the renal transplant waiting list exist in pediatrics. Whether these disparities are attributable to differences in time of presentation to a nephrologist, physician bias in identification of transplant candidates, or patient preferences warrants further study.

Myocardial blood flow and myocardial uptake of (201)Tl and (99m)Tc-sestamibi during coronary vasodilation induced by CGS-21680, a selective adenosine A(2A) receptor agonist

BACKGROUND

We investigated the hemodynamic and coronary vasodilatory effects of CGS-21680, a potent selective adenosine A(2A) agonist, as well as its potential use as a new stress modality in combination with perfusion scintigraphy.

METHODS AND RESULTS

A stenosis of the left anterior descending coronary artery (LAD) was produced in dogs to reduce the reactive hyperemic response to <20%. Adenosine and CGS-21680 were then separately infused to maximize left circumflex coronary artery (LCx) flow velocity. (201)Tl (0.5 mCi) and (99m)Tc-sestamibi (5 mCi) were injected at the maximal dose of CGS-21680. Heart rate decreased with adenosine but increased during CGS-21680 infusion (P<0.005). The decrease in systolic blood pressure was more prominent with adenosine than with CGS-21680 (P<0.005). In the control LCx zone, maximal myocardial blood flow (MBF) (measured by radioactive microspheres) increased 3.1-fold during adenosine infusion (P<0.005) and 3.8-fold during CGS-21680 infusion (P<0.005). In the stenotic LAD zone, MBF did not change significantly. During adenosine and CGS-21680 infusion, stenosis/control zone MBF ratios were comparable (0.32+/-0.11 versus 0.27+/-0.10, P=NS), and transmural (201)Tl and (99m)Tc-sestamibi count-activity ratios (0.48+/-0.11 and 0.51+/-0.09, respectively) were also comparable (P=NS). Myocardial scintigraphy uncovered perfusion defects in all dogs.

CONCLUSIONS

CGS-21680 elicits coronary vasodilation comparable to that of adenosine and produces profound heterogeneity of MBF and of (201)Tl and (99m)Tc-sestamibi myocardial uptake, rendering it a promising agent for pharmacological myocardial perfusion imaging.

Purification and embryotropic roles of tissue inhibitor of metalloproteinase-1 in development of "HanWoo" (Bos taurus coreanae) oocytes co-cultured with bovine oviduct epithelial cells

This study was conducted to purify a tissue inhibitor of metalloproteinase (TIMP)-1 in a serum-free medium conditioned with bovine oviduct epithelial cells (BOEC) and to evaluate its effect on development of "HanWoo" (Bos taurus coreanae) embryos to the blastocyst stage. In the first study using SDS-PAGE electrophoresis, the presence of 32 kDa proteins, which contains TIMP-1, was detected in the medium conditioned with BOEC, and TIMP-1 was then purified from the medium by gel filtration and HPLC techniques. When examined TIMP-1 secretion, fluorescent foci indicating the secretion of TIMP-1 were found after stained BOEC with fluorescein isothiocyanate. In the next experiment, two-cell embryos derived from in vitro-fertilization were cultured in a serum-free medium, to which 0, 1.25, 2.5 or 5 microg/ml of purified TIMP-1 was supplemented. More (P<0.05) embryos developed to the morula and blastocyst stages after the addition of 2.5 microg/ml to culture medium than after no addition. In conclusion, our data indicate that BOEC secrete TIMP-1 and this glycoprotein promotes the prehatched development of "HanWoo" embryos derived from in vitro-fertilization.

For-profit versus not-for-profit dialysis care for children with end stage renal disease

OBJECTIVE

Over the last 2 decades, for-profit dialysis units have become the most common providers of renal replacement therapy for adults with end stage renal disease (ESRD) and have had an increasing role in the dialysis of children. We undertook a study to determine whether dialysis facility profit status influences the choice of dialysis therapy in the pediatric population.

DESIGN

Cross-sectional study of national data from the Health Care Financing Administration.

SETTING

Free-standing and hospital-based outpatient dialysis facilities in the United States.

PATIENTS

A total of 1568 children and adolescents (</=19 years of age) eligible for US Medicare ESRD benefits in 1994.

OUTCOME MEASURES

The association between dialysis modality choice and the profit status of the facility. Crude associations were estimated by the OR of a patient being treated with peritoneal dialysis (PD) versus hemodialysis at nonprofit versus for-profit facilities. Adjusted associations were estimated using logistic regression analysis.

RESULTS

In bivariate analysis, children with ESRD dialyzed at nonprofit facilities were nearly three times as likely as those at for-profit facilities to be on PD (OR: 2.9; 95% CI: 2.3,3.6). In multivariate analysis, after controlling for patient age, sex, race, cause and duration of ESRD, free-standing versus hospital-based facility, and the pediatric expertise of the facility, patients at nonprofit facilities were more than twice as likely as those dialyzed at for-profit facilities to be on PD (OR: 2.3; 95% CI: 1.6, 3.4). After taking into account the clustering of patients within facilities, the association between nonprofit status and the use of PD persisted (OR: 2.2; 95% CI: 1.5,3.2).

CONCLUSIONS

Children with ESRD treated at nonprofit facilities are more likely to receive PD than are those treated at for-profit facilities even after controlling for other patient and facility characteristics. This finding suggests that clinical decision making for pediatrics may be influenced by the ownership of the health care facility in which the patient is treated.

Dynamic behavior of driven interfaces in models with two absorbing states

We study the dynamics of an interface (active domain) between different absorbing regions in models with two absorbing states in one dimension: probabilistic cellular automata models and interacting monomer-dimer models. These models exhibit a continuous transition from an active phase into an absorbing phase, which belongs to the directed Ising (DI) universality class. In the active phase, the interface spreads ballistically into the absorbing regions and the interface width diverges linearly in time. Approaching the critical point, the spreading velocity of the interface vanishes algebraically with a DI critical exponent. Introducing a symmetry-breaking field h that prefers one absorbing state over the other drives the interface to move asymmetrically toward the unpreferred absorbing region. In Monte Carlo simulations, we find that the spreading velocity of this driven interface shows a discontinuous jump at criticality. We explain that this unusual behavior is due to a finite relaxation time in the absorbing phase. The crossover behavior from the symmetric case (DI class) to the asymmetric case (directed percolation class) is also studied. We find the scaling dimension of the symmetry-breaking field y(h)=1.21(5).

Does greater pediatric experience influence treatment choices in chronic disease management? Dialysis modality choice for children with end-stage renal disease

OBJECTIVE

To determine whether treatment choice for children with end-stage renal disease varies with greater pediatric experience at the dialysis facility.

DESIGN

National cross-sectional study.

SETTING

Outpatient dialysis facilities throughout the United States.

PATIENTS

All children (age, < or = 19 years) undergoing dialysis in 1990, identified using the Medicare End-stage Renal Disease registry (1990 facility survey and quarterly dialysis records).

OUTCOME MEASURES

The odds of receiving peritoneal dialysis vs hemodialysis according to the pediatric experience of the facility. "Pediatric experience" for dialysis facilities was defined as the number of patients 19 years old or younger divided by the total number of patients treated at that facility. Adjustment, using multiple logistic regression, was made for differences in age, sex, cause and duration of end-stage renal disease, income, education, and facility characteristics.

RESULTS

In 1990, there were 1256 patients 19 years old or younger who underwent a single-treatment modality at a single facility for most of the year. Sixty-three percent (790/ 1256) were treated at facilities with fewer than 5% of patients younger than 19 years. Thirty-six percent were treated at centers with less than 1% of pediatric patients. In a multivariate analysis, pediatric experience in a facility was independently associated with the use of peritoneal dialysis in children. Children treated at facilities with more than 10% pediatric patients were 60% more likely to be treated with peritoneal dialysis rather than hemodialysis compared with children treated at facilities with fewer than 1% of pediatric patients, even after controlling for patient age, race, income, education, cause and duration of end-stage renal disease, and facility characteristics such as hospital-based vs independent unit and for-profit vs not-for-profit status (odds ratio, 1.6; 95% confidence interval, 1.1-2.3).

CONCLUSIONS

Children receiving care at dialysis facilities that have greater experience with pediatric patients are more likely to receive peritoneal dialysis than hemodialysis, a therapy with recognized clinical benefits for children that is inherently less resource intensive than is hemodialysis.

Racial differences in choice of dialysis modality for children with end-stage renal disease

OBJECTIVE

Black-white disparities in the use of specific medical and surgical services have been reported in adult populations. Such disparities are not well documented in children. We sought to determine whether racial disparities in the use of medical services exist among children with chronic illness who have similar health insurance, specifically the choice of dialysis modality for individuals with end-stage renal disease.

DESIGN

National cross-sectional study.

SETTING

Outpatient dialysis facilities throughout the United States.

PATIENTS AND PARTICIPANTS

All Medicare-eligible children (age, </=19 years) undergoing renal replacement therapy in 1990 in the United States, using data from the Medicare ESRD registry.

OUTCOME MEASURES

The odds of receiving hemodialysis versus peritoneal dialysis according to race. Adjustment was made for differences in age, gender, cause, and duration of end-stage renal disease, income, education, and facility characteristics using multiple logistic regression.

RESULTS

In 1990, 870 white and 368 black children received chronic (>1 year) renal replacement therapy in the United States. In bivariate analysis, blacks were two times (odds ratio [OR], 2.2; 95% confidence interval [CI], 1.7, 2.8) more likely than whites to receive hemodialysis versus peritoneal dialysis. After controlling for other patient and facility characteristics in multivariate analysis, black children were still significantly more likely than white children to receive hemodialysis (OR, 2.4; 95% CI, 1.7, 3.5).

CONCLUSIONS

Black race is strongly associated with the use of hemodialysis in children. Family, patient, or provider preferences could account for the difference in choice of therapy by race.

Cyclic AMP-dependent expression of the Escherichia coli serC-aroA operon

The Escherichia coli serC-aroA operon encodes biosynthetic enzymes for unrelated amino acid biosynthetic pathways leading to the synthesis of serine and the aromatic amino acids. A serC-aroA-lac translational fusion was constructed in the vector pMC1403. Synthesis of beta-galactosidase from the serC-aroA-lac fusion was found to be enhanced in the presence of lactose as the sole carbon source. This enhancement was not observed in strains containing a cya or crp mutant. However, the exogenous addition of cAMP greatly increased the beta-galactosidase synthesis in the cya mutant strain. The serC-aroA mRNA content, analyzed by a dot blot assay, also appeared to increase in the serC+ aroA+ cells after the exogenous addition of cAMP. These findings unambiguously indicate that the expression of the serC-aroA operon is positively controlled by cAMP.

A relationship between the activities of hepatic lanosterol 14 alpha-demethylase and 3-hydroxy-3-methylglutaryl-CoA reductase

At 1-2 h after intragastric administration of ketoconazole, a cytochrome P-450 inhibitor, to rats, there was a 50-60% decrease in the activity of hepatic 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase. Inhibition reached a maximum at 6-12 h after the drug was given, but after 24 h enzyme activity was stimulated by 60%. The rates of synthesis of hepatic non-saponifiable lipids in vivo showed a similar time-dependent pattern of change. During the first few hours after drug administration, the hepatic cytochrome P-450-dependent metabolism of lanosterol was suppressed in vivo. However, 24 h after treatment, this activity was stimulated, an effect which was also observed by pre-treatment of the rats with the drug for several days. Suppression of hepatic HMG-CoA reductase and lanosterol 14 alpha-demethylase activities was accompanied by a relative increase in the accumulation of labelled polar sterols in the liver in vivo. In the intestine, ketoconazole also resulted in a rapid decline in the rate of synthesis of non-saponifiable lipids and an inhibition of lanosterol 14 alpha-demethylation in vivo. However, in contrast with the liver, there was no stimulation of non-saponifiable lipid synthesis after 24 h.