Biomedical subjects

N J Petersen

Publications and source records attributed to N J Petersen.

At least 19 recordsLinked to original sources

PubMed2001

Cytokines and cytokine receptors in advanced heart failure: an analysis of the cytokine database from the Vesnarinone trial (VEST).

BACKGROUND: Previous reports have shown that elevated circulating levels of cytokines and/or cytokine receptors predict adverse outcomes in patients with heart failure. However, these studies were limited by small numbers of patients and/or they were performed in a single center. In addition, these studies did not have sufficient size to address the influence of age, race, sex, and cause of heart failure on the circulating levels of these inflammatory mediators in patients with heart failure. METHODS AND RESULTS: We analyzed circulating levels of cytokines (tumor necrosis factor [TNF] and interleukin-6) and their cognate receptors in 1200 consecutive patients who were enrolled in a multicenter clinical trial of patients with advanced heart failure. This analysis constitutes the largest analysis of cytokines and cytokine receptors to date. Analysis of the patients receiving placebo showed that increasing circulating levels of TNF, interleukin-6, and the soluble TNF receptors were associated with increased mortality. In men, there was a linear increase in circulating levels of TNF with advancing age. Women < or = 50 years of age had relatively low levels of TNF, but TNF levels were disproportionately higher in women >50 years of age. No differences existed in cytokines and/or cytokine receptors in whites versus nonwhites, and circulating levels of cytokines and cytokine receptors were significantly greater in patients with ischemic heart disease. CONCLUSIONS: Cytokines and cytokine receptors are independent predictors of mortality in patients with advanced heart failure. Moreover, circulating levels of cytokines are modified by age, sex, and cause of heart failure.

Adult↗

PubMed2001

Monolithic integration of optical waveguides for absorbance detection in microfabricated electrophoresis devices.

The fabrication and performance of an electrophoretic separation chip with integrated optical waveguides for absorption detection is presented. The device was fabricated on a silicon substrate by standard microfabrication techniques with the use of two photolithographic mask steps. The waveguides on the device were connected to optical fibers, which enabled alignment free operation due to the absence of free-space optics. A 750 microm long U-shaped detection cell was used to facilitate longitudinal absorption detection. To minimize geometrically induced band broadening at the turn in the U-cell, tapering of the separation channel from a width of 120 down to 30 microm was employed. Electrical insulation was achieved by a 13 microm thermally grown silicon dioxide between the silicon substrate and the channels. The breakdown voltage during operation of the chip was measured to 10.6 kV. A separation of 3.2 microM rhodamine 110, 8 microM 2,7-dichlorofluorescein, 10 microM fluorescein and 18 microM 5-carboxyfluorescein was demonstrated on the device using the detection cell for absorption measurements at 488 nm.

Electrophoresis, Capillary↗

PubMed2001

Effects of vesnarinone on peripheral circulating levels of cytokines and cytokine receptors in patients with heart failure: a report from the Vesnarinone Trial.

STUDY OBJECTIVES: Proinflammatory cytokines may contribute to disease progression in heart failure by virtue of the direct toxic effects that these molecules exert on the heart and the circulation. Accordingly, there is interest in developing therapeutic agents with anticytokine properties that might be used as adjunctive therapy to modulate proinflammatory cytokine levels in patients with heart failure. Previous experimental studies suggested that vesnarinone has potent anticytokine properties in vitro. Therefore, we examined the effects of vesnarinone on circulating levels of cytokines and cytokine receptors in a large-scale, multicenter, clinical trial of patients with moderate-to-advanced heart failure: the Vesnarinone Trial (VEST). METHODS: Circulating levels of tumor necrosis factor (TNF)-alpha, soluble TNF-receptor type 1, soluble TNF-receptor type 2, as well as interleukin (IL)-6 and soluble IL-6 receptor (sIL-6R) were measured on plasma samples by enzyme-linked immunosorbent assay at baseline and at 24 weeks in patients who were receiving placebo (n = 352), 30 mg of vesnarinone (n = 367), and 60 mg of vesnarinone (n = 327). RESULTS: Treatment with 30 mg and 60 mg of vesnarinone had no effect on circulating levels of cytokines or cytokine receptors in patients with advanced heart failure over a 24-week period. CONCLUSIONS: In contrast to the potent anticytokine effects observed with vesnarinone in experimental studies in vitro, the results of this clinical study suggest that vesnarinone does not have any measurable anticytokine effects in vivo in patients with moderate-to-advanced heart failure.

Cardiotonic Agents↗

PubMed2001

What's being used at home: a household pesticide survey.

OBJECTIVE: Since very little is known about the health effects that household pesticides have on children, we conducted this survey to identify what pesticides are being used in the home, where they are being used and stored, and what methods are used for their disposal. METHODS: In the spring of 1999 we conducted a survey in a community in the state of Arizona, in the United States of America, on the border with Mexico. To be eligible to participate in the survey, households had to have used a pesticide in the 6 mo prior to the survey and to have at least one child under the age of 10 years. We gathered general information on pesticide usage, storage, and disposal, in addition to specific information about each of the pesticides currently being used and/or stored in the home. RESULTS: In the 107 households surveyed, we found 148 pesticide products, for a mean of 1.4 per household. Half of the pesticides were stored less than 4 feet (1.22 m) from the ground, at a level a child could reach. Seventy percent of all the pesticides were stored inside the home, with the kitchen being the storage room most often mentioned. The kitchen was also the room where most of the pesticides were used, with 69% of the respondents saying they had used at least one pesticide there. CONCLUSIONS: From our research we conclude that it will be important to continue to investigate all avenues of pesticide exposure in order to fully evaluate childhood exposures. Understanding household pesticide use and developing a model of exposure will help in this process. Profiles of the use, storage, and disposal of products will also guide the development of effective education and poison prevention programs in the community.

Child↗

PubMed1999

Geographic variations in utilization rates in Veterans Affairs hospitals and clinics.

BACKGROUND: In the United States, geographic variation in hospital use is common. It is uncertain whether there are similar geographic variations in the health care system of the Department of Veterans Affairs (VA), which differs from the private sector because it predominantly serves men with annual incomes below $20,000, has a central system of administration, and uses salaried physicians. Thus, it might be less likely to have geographic variations. METHODS: We used VA data bases to obtain information on patients treated for eight diseases (chronic obstructive pulmonary disease, pneumonia, congestive heart failure, angina, diabetes, chronic renal failure, bipolar disorder, and major depression). We analyzed their use of hospital and outpatient services by assessing the risk-adjusted numbers of hospital days (the average number of days a patient spent in the hospital per 12 months of follow-up, regardless of the number of hospital stays), hospital-discharge rates, and clinic-visit rates from 1991 through 1995 for the entire system and within the 22 geographically based health care networks. RESULTS: We found substantial geographic variation in hospital use for all eight cohorts of patients and all the years studied. Variations in the numbers of hospital days per person-year among the networks were greatest among patients with chronic obstructive pulmonary disease (ranging from a factor of 2.7 to a factor of 3.1) during a given year and smallest among patients with angina (ranging from a factor of 1.5 to a factor of 2.1). Levels of hospital use were highest in the Northeast and lowest in the West. The variation in the rates of clinic visits for principal medical care among the networks ranged from a factor of approximately 1.6 to a factor of 4.0; variations in the rates were greatest among patients with chronic renal failure and smallest among patients with chronic obstructive pulmonary disease. There was no clear geographic pattern in the rates of outpatient-clinic use. CONCLUSIONS: There are significant geographic variations in the use of hospital and outpatient services in the VA health care system. Because VA physicians are unable to increase their income by changing their patterns of practice, our findings suggest that their practice styles are similar to those of other physicians in their geographic regions.

Chronic Disease↗

PubMed1999

The hospital multistay rate as an indicator of quality of care.

OBJECTIVES: To evaluate the hospital multistay rate to determine if it has the attributes necessary for a performance indicator that can be applied to administrative databases. DATA SOURCES/STUDY SETTING: The fiscal year 1994 Veterans Affairs Patient Treatment File (PTF), which contains discharge data on all VA inpatients. STUDY DESIGN: Using a retrospective study design, we assessed cross-hospital variation in (a) the multistay rate and (b) the standardized multistay ratio. A hospital's multistay rate is the observed average number of hospitalizations for patients with one or more hospital stays. A hospital's standardized multistay ratio is the ratio of the geometric mean of the observed number of hospitalizations per patient to the geometric mean of the expected number of hospitalizations per patient, conditional on the types of patients admitted to that hospital. DATA COLLECTION/EXTRACTION METHODS: Discharge data were extracted for the 135,434 VA patients who had one or more admissions in one of seven disease groups. PRINCIPAL FINDINGS: We found that 17.3 percent (28,300) of the admissions in the seven disease categories were readmissions. The average number of stays per person (multistay rate) for an average of seven months of follow-up ranged from 1.15 to 1.45 across the disease categories. The maximum standardized multistay ratio ranged from 1.12 to 1.39. CONCLUSIONS: This study has shown that the hospital multistay rate offers sufficient ease of measurement, frequency, and variation to potentially serve as a performance indicator.

Algorithms↗

PubMed1998

The Veterans Affairs medical care system: hospital and clinic utilization statistics for 1994.

OBJECTIVES: The authors describe the role the Veterans Affairs (VA) medical system plays as a provider of clinic and hospital services by examining utilization levels and users' characteristics. METHODS: The Veterans Affairs hospital discharge database, the Veterans Affairs outpatient clinic files, and the veteran population files were used to estimate the number of persons using the Veterans Affairs medical care system in 1994 and the intensity of their clinic and hospital use. Demographic and clinical characteristics of users were tabulated. RESULTS: In 1994, 2.7 million veterans, 10.3% of all US veterans, and approximately 23% of veterans who would have met the statutory eligibility requirements for Veterans Affairs care, used the hospital and/or clinic components of the Veterans Affairs medical system. Sixty-three percent of the system's users were younger than age 65, and 10.5% were women. These 2.7 million veterans had 901,665 Veterans Affairs hospital stays, 15.5 million bed-days, and 31.2 million outpatient visits in fiscal year 1994. The average number of hospitalizations per hospital user was 1.71; the average number of visits per clinic user was 11.7. Medical, surgical, and psychiatric diagnosis-related groups (DRGs) accounted for 56%, 21%, and 23%, respectively, of hospitalizations, but psychiatric diagnosis-related groups accounted for 43% of all inpatient days. Principal medicine clinic visits and psychiatry clinic visits accounted for 21% and 16% of Veterans Affairs ambulatory care. CONCLUSIONS: Because the patient population served by the Veterans Affairs system is skewed in a number of ways, its contribution as a provider of health services in the United States varies by gender, age, socioeconomic status, and diagnosis.

Adult↗

PubMed1998

Impact of an all-inclusive diagnosis-related group payment system on inpatient utilization.

OBJECTIVES: Although case-based payment is one of the main reimbursement mechanisms for hospitals, little is known about its effects in the general population. Prior studies have focused on Medicare or on all-payer systems in particular states. This study estimates the effect of a prospective payment system based on diagnosis-related groups (DRGs) nationwide in the Department of Veterans Affairs. METHODS: Multiple regression analysis was used to estimate the effect of Department of Veterans Affairs's diagnosis-related group system separately for 22 diagnoses. The dependent variables were length of stay, inpatient days per patient, and discharges per patient. Covariates included patient, hospital, and area characteristics. RESULTS: Department of Veterans Affairs's diagnosis-related group system reduced lengths of stay and inpatient days per patient. The largest impacts were for the psychiatric diagnoses and several surgical procedures. The magnitudes of the effects were generally moderate. Department of Veterans Affairs's case-based system had a negligible effect on discharges per patient. CONCLUSIONS: Per case reimbursement is a potentially useful tool for improving the efficiency of inpatient care for all types of diagnoses and age groups. The effect may be larger than estimated here because of institutional barriers and caps on financial impact.

Aged↗

PubMed1997

A case-control study of lung cancer mortality in six Gila Basin, Arizona smelter towns.

To investigate factors related to lung cancer mortality in six Arizona copper smelter towns, we identified 185 lung cancer cases and two matched controls per case from decedent residents during 1979-1990. Detailed information on lifetime residential, occupational, and smoking history was obtained by structured telephone interviews with knowledgeable informants. Interviews were completed for 82% of 183 eligible cases and 88% of the targeted number (366) of controls. Estimated historical environmental exposures to smelter emissions, based on atmospheric diffusion modeling of measured SO2 concentrations, were linked with residential histories to derive individual profiles of residential exposure. Occupational histories were characterized by potential exposure to smelter emissions, asbestos, and ionizing radiation. Conditional logistic regression was used to compare study factors in cases and controls with adjustment for potential confounding factors: gender, Hispanic ethnicity, and smoking. In overall and gender-specific analyses, no statistically significant associations were observed between lung cancer risk and any of the measures of residential exposure to smelter emissions considered (town of residence at time of death, highest level of exposure, and duration or cumulative exposure above background levels), or any of the estimated occupational exposures (definite or potential asbestos, potential ionizing radiation, definite or potential smelter). Among male residents of some, but not all, towns, there was some evidence of a positive association between lung cancer risk and reported copper smelter-related employment (reported as definite), with the highest risk observed for Miami, Arizona. This study provided little evidence of a positive association between lung cancer mortality and residential exposure to smelter emissions. Specific factors associated with the apparent heterogeneity in lung cancer risk across study towns cannot be identified in this community-based study.

Arizona↗

PubMed1996

Long-term outcomes of patients receiving percutaneous endoscopic gastrostomy tubes.

OBJECTIVE: Percutaneous endoscopic gastrostomy (PEG) tube placement is the preferred method for long-term enteral feeding of patients who are unable to take food by mouth. Despite the widespread acceptance of the procedure, no large-scale study of the long-term outcomes of patients receiving PEG tubes has been reported. The objective of this study was to determine the survival of patients in whom PEG tubes are placed. DESIGN: Retrospective cohort study using data obtained from two computerized databases. SETTING: Department of Veterans Affairs hospitals. PATIENTS: Seven thousand three hundred sixty-nine patients who received a PEG tube in fiscal years 1990 through 1992. RESULTS: For the 7,369 patients, the mean age was 68.1 years and 98.6% were men. PEG tubes were most commonly places in patients with cerebrovascular disease (18.9%), other organic neurologic disease (28.6%), or head and neck cancer (15.7%). Although the complication rate of the procedure itself was low (4%), because of the severity of their underlying disease, 1,732 patients (23.5%) died during the hospitalization in which the PEG tube was placed. The median survival of the full cohort was 7.5 months. CONCLUSIONS: This study documents the widespread placement of PEG tubes in severely ill patients, half of whom are in the terminal phase of their illness. Further study is needed to determine whether these patients benefit from PEG tube placement in terms of their quality of life and survival.

Adolescent↗

PubMed1995

Selecting disease-outcome pairs for monitoring the quality of hospital care.

Health care payors and providers are increasingly monitoring hospital discharge data bases for adverse events as markers for quality of care. The principal criticisms of these analyses have focused on the impediments to risk adjustment posed by the incompleteness and inaccuracy of the data bases. However, efforts to address the inadequacies of the data bases will not correct deficiencies of the analytic process. These deficiencies arise from the application of one adverse outcome to all disease states. Instead, analysis should be restricted to comparisons of subgroups of patients in which a close fit exists between the quality of care for the disease state and the expected outcome. Furthermore, these disease-outcome pairs should be minimally subject to measurement error. The authors present a conceptual framework for developing such meaningful disease-outcome pairs, and using the hospital discharge data base of the Department of Veterans Affairs, show how the framework can be used to devise a monitoring strategy for re-admission.

Data Collection↗

PubMed1994

Changes in VA hospital use 1980-1990.

During the 1980s several changes occurred within and outside the Veterans Affairs medical system which may have affected levels of Veterans Affairs (VA) hospital use. We performed a secondary analysis of the 1980-1990 national VA hospital discharge database and Veteran Population Files to examine trends in VA hospital use and to assess effects of the aging of the veteran population. Between 1980 and 1990 discharges increased by 7% despite a 6% drop in the number of veterans. Overall the crude discharge rate increased by 13% and the user rate by 1%. Most of the change was attributable to the fact that as the decade progressed, the veteran population was comprised of proportionately older veterans, who are higher users of hospital care than younger veterans. The 11% increase in the multiple stay ratio was not attributable to aging. Examination of age-specific utilization rates showed that veterans younger than age 45 had consistent increases in use, whereas use by older veterans declined. Our findings indicate that change in the age composition of the veteran population is responsible for some but not all of the increase in VA hospital use in the last decade. The increase in use by young veterans may reflect increasing barriers to access to non-VA care. Declines in use by older veterans may indicate that VA has been successful in shifting the locus of care from the hospital to the ambulatory and long-term care settings.

Age Distribution↗

PubMed1993

The incidence of perioperative myocardial infarction in men undergoing noncardiac surgery.

OBJECTIVES: To determine the incidence of and risk factors for perioperative myocardial infarction with noncardiac surgery and to test the accuracy of a risk stratification system. DESIGN: Prospective cohort study. SETTING: A large urban Veterans Affairs hospital. PARTICIPANTS: A total of 1487 men older than 40 years undergoing major, nonemergent, noncardiac operations. MEASUREMENTS: Infarction was established by at least two of the following: development of new Q waves, typical change in creatine kinase MB, and positive technetium pyrophosphate scintigraphy. Patients were stratified preoperatively into high-, intermediate-, low-, and negligible-risk strata based on clinical markers corresponding to different levels of coronary artery disease prevalence. MAIN RESULTS: Patients with coronary disease (high-risk stratum) had a 4.1% incidence of infarction (13 of 319; 95% CI, 1.8% to 6.4%); patients with peripheral vascular disease but no evidence of coronary disease (intermediate-risk stratum) had a 0.8% incidence (2 of 260, upper bound of CI, 2.0%); patients with high atherogenic risk factor profiles but no clinical atherosclerosis (low-risk stratum) had a 0% incidence (0 of 256, upper bound of CI, 1.2%). No cardiac deaths occurred in 652 men who had no atherosclerosis and low atherogenic risk factor profiles (the negligible-risk stratum). Factors independently associated with infarction included age more than 75 years (adjusted odds ratio, 4.77; CI, 1.17 to 19.41), signs of heart failure on the preoperative examination (adjusted odds ratio, 3.31; CI, 0.96 to 11.38), coronary disease (adjusted odds ratio, 10.39; CI, 2.27 to 47.46), and a planned vascular operation (adjusted odds ratio, 3.72; CI, 1.12 to 12.37). CONCLUSIONS: Coronary artery disease is the major risk factor for perioperative infarction. The stratification scheme identifies subsets of patients with different risks, and finer within-stratum distinctions can be made using additional variables.

Adult↗

PubMed1985

Infections with Mycobacterium chelonei in patients receiving dialysis and using processed hemodialyzers.

Between April and November 1982, 27 of 140 patients in a hemodialysis center in Louisiana were infected with rapidly growing mycobacteria; 14 had bacteremia alone, 3 had soft-tissue infections, 1 had an access-graft infection, and 9 had widely disseminated disease. Of 26 identified isolates, 25 were Mycobacterium chelonei ssp. abscessus, and one was an M. chelonei-like organism. One factor common to all patients was exposure to processed hemodialyzers (artificial kidneys). Environmental sampling of the water-treatment system showed widespread contamination with nontuberculous mycobacteria, which were also recovered from the patient's side (blood compartment) of five of 31 hemodialyzers that had been processed and were ready for use. The formaldehyde concentration was less than 2% in two of three such contaminated dialyzers tested. We hypothesize that patients became infected when their blood circulated through processed dialyzers that contained viable rapidly growing mycobacteria. This outbreak demonstrates that hemodialysis patients may be at risk for developing infections with rapidly growing mycobacteria and that such infections may go unrecognized when routine culture methods are used. It also emphasizes the importance of using effective procedures to disinfect dialyzers in hemodialysis centers.

Adult↗

PubMed1984

Recommendations for the care of automated peritoneal dialysis machines: can the risk of peritonitis be reduced?

Automated peritoneal dialysis systems have helped make intermittent peritoneal dialysis an alternative to hemodialysis for long-term management of patients with end-stage renal disease. However, if not cleaned and maintained properly, these machines provide a reservoir for pathogens. The microbiologic barriers in these machines are not impenetrable, but sterile dialysate fluid can be produced if the machines are adequately cleaned and disinfected. Potential shortcomings of the microbiologic barriers are discussed, and guidelines to prevent contamination of the internal parts of a machine are suggested.

Bacterial Infections↗

PubMed1984

Intrinsic bacterial contamination of a commercial iodophor solution: investigation of the implicated manufacturing plant.

After an outbreak of peritoneal infections attributed to intrinsic contamination of a poloxamer-iodine solution with Pseudomonas aeruginosa, the manufacturer of the contaminated solution permitted investigation and sampling of materials within the plant. Pseudomonas spp. were recovered from two different unopened lots of solution and from numerous water samples obtained at the plant. The isolates from water identical to those of an isolate recovered from Prepodyne solution (West-Agro Chemical Co., Inc., Westwood, Kans., manufactured for AMSCO Medical Products Div., Erie, Pa.) manufactured 1 month earlier at the same plant. P. aeruginosa was not recovered from incoming city water. P. aeruginosa was recovered from sterile water and poloxamer-iodine after 48 h of incubation in a plant polyvinyl chloride pipe. Scanning electron micrographs of polyvinyl chloride pipe used in the plant showed massive concentrations of rod-shaped and coccobacillary cells apparently embedded in interior deposits of the pipe. Manufacturers of iodophors should be aware that pipes or other surfaces colonized with bacteria may be a source of contamination of their products.

Journal Article↗

PubMed1983

Outbreak of pyrogenic reactions at a dialysis center. Association with infusion of heparinized saline solution.

Twenty-three pyrogenic reactions occurred in 16 patients undergoing hemodialysis at a private dialysis center in the south central United States between November 23 and December 2, 1978. No deaths were attributed to reactions; however, 10 patients were hospitalized for observation after experiencing a reaction. Cultures of all blood specimens obtained from the patients gave negative results. Chills (75 percent), nausea and/or vomiting (30 percent), and fever (90 percent) were the most common signs and symptoms, with mean times of onset after starting dialysis of 1.1, 1.6, and 3.6 hours, respectively. An epidemiologic and laboratory investigation documented that reactions occurred only in patients who had anticoagulation with a dilute solution of heparin. Analyses of heparinized saline solution used during the outbreak revealed a bacterial count of 7.4 X 10(5)/ml and a bacterial endotoxin level of 1,300 ng/ml. Acinetobacter calcoaceticus var. Iwoffi was isolated from the solution. Diluted heparin solution was prepared at the dialysis center by adding commercially supplied sodium heparin to 0.9 percent sodium chloride infusion fluid. Bacteria and endotoxin were not detected in vials of stock heparin and bags of unopened 0.9 percent sodium chloride infusion fluid. We concluded that contamination of the solution occurred at the dialysis center. After changes in the preparation and use of heparin were instituted on December 4, 1978, no pyrogenic reactions occurred in more than 400 subsequent dialyses.

Acinetobacter↗

PubMed1983

Dialysis encephalopathy and aluminum exposure: an epidemiologic analysis.

We identified 55 patients with dialysis encephalopathy in six dialysis centers studied by means of a uniform clinical classification. Dialysis encephalopathy was the direct cause of death in most cases, and the disease appeared to significantly shorten survival. The overall attack rate of dialysis encephalopathy was 4% and varied among dialysis centers from 2.2% to 14.7%. In two centers with adequate data, the attack rate for dialysis encephalopathy rose significantly with increasing cumulative aluminum exposure via dialysate, and the mean cumulative aluminum exposure for patients with the disease was significantly higher than that for all other patients at risk. We further demonstrated that the cumulative level of aluminum tolerated by the patient before onset of symptoms was inversely related to the average aluminum concentration of dialysate water.

Aluminum↗