Biomedical subjects

R A Wolfe

Publications and source records attributed to R A Wolfe.

At least 109 records · Page 6Linked to original sources

PubMed1990

Micro-area variation in hospital use.

Many recent studies have demonstrated that hospital utilization rates vary widely across small geographic areas. The variation is often attributed to the style of practice of the provider. This study demonstrates that hospital utilization varies widely between "micro" areas within individual hospital market areas. Further, the study demonstrates that hospital utilization rates within a hospital market area are more similar to each other than to rates in "micro" areas within other hospital market areas. After adjustment for available demographic, socioeconomic, and epidemiological factors, the utilization rates within "micro" areas are highly related to the group of hospitals that dominates the market area. After simultaneously adjusting for age and poverty, the market share-dominant group explains 35 percent of the variance in surgical use rates of "micro" areas and 39 percent of the variance in medical use rates.

Adolescent↗

PubMed1989

Disparities in incidence of diabetic end-stage renal disease according to race and type of diabetes.

The incidence of end-stage renal disease in patients with diabetes mellitus is reportedly higher among blacks than among whites. This finding may be explained by the greater prevalence of diabetes among blacks. The relation of the type of diabetes to the risk of diabetic end-stage renal disease is largely unstudied. We addressed these issues in a study of all the black and white diabetic patients with end-stage renal disease (470 blacks and 861 whites) reported to the Michigan Kidney Registry who began treatment during 1974 through 1983. We also reviewed the medical records of a subpopulation of such patients (284 blacks and 310 whites) who were less than 65 years of age at the start of treatment for end-stage renal disease to determine what type of diabetes they had. In this study, we made use of national data on the prevalence of diabetes. We found that the incidence of diabetic end-stage renal disease was 2.6-fold higher (P less than or equal to 0.0001) among blacks after we adjusted for the higher prevalence of diabetes among blacks, with the excess risk occurring predominantly among blacks with non-insulin-dependent diabetes mellitus (NIDDM). Most black patients with diabetic end-stage renal disease had NIDDM (77 percent), whereas most white patients with diabetic end-stage renal disease had insulin-dependent diabetes mellitus (IDDM) (58 percent) (P less than or equal to 0.0005 for the difference between the races). For both races combined, the risk of diabetic end-stage renal disease during the 10-year period we studied was markedly greater for patients with IDDM (5.8 percent) than for those with NIDDM (0.5 percent). Our results indicate an increased risk of diabetic end-stage renal disease among blacks as compared with whites, particularly blacks with NIDDM. Although the risk of diabetic end-stage renal disease is higher in patients with IDDM, the majority of patients with diabetic end-stage renal disease in the population we studied had NIDDM.

Adolescent↗

PubMed1989

Occupational mercury exposure and male reproductive health.

This retrospective cohort study was designed to investigate the relationship of male occupational exposure to elemental mercury and several reproductive outcomes. All subjects worked at least 4 months between 1953 and 1966 at a plant that used elemental mercury; 247 white male employees who had the highest exposures were compared to 255 matched nonexposed employees. Individual exposure to mercury was estimated from urinary mercury measurement records. Information on reproductive history and potential confounding variables was obtained through personal interview with each of the employees and with a subset of their wives. No associations were demonstrated between mercury exposure and decreased fertility or increased rates of major malformations or serious childhood illnesses. After controlling for previous miscarriage history, mercury exposure was not a significant risk factor for miscarriage. Because of this study's potential problems with long-term recall, further studies of the effect of mercury on pregnancy outcome are warranted in other populations.

Abortion, Spontaneous↗

PubMed1989

Independence in activities of daily living for end-stage renal disease patients: biomedical and demographic correlates.

Factors associated with physical well-being were examined in a population-based sample of adult end-stage renal disease (ESRD) patients in Michigan (n = 459). The dependent variables were two measures of physical functioning: (1) a ten-item measure of activities of daily living (ADL), and (2) the 45-item physical dysfunction dimension of the Sickness Impact Profile (SIP). Independent variables included four modalities of treatment (in-center hemodialysis, continuous ambulatory peritoneal dialysis [CAPD], related transplant, and cadaver transplant); primary cause of ESRD (eg, diabetes, glomerulonephritis); comorbidity (other illnesses besides primary cause of ESRD); and demographic characteristics (sex, race, age, marital status, education). ADL and SIP unadjusted mean scores differed significantly by category for each of the eight study factors (analysis of variance [ANOVA], P less than 0.0001), with the exception of sex for SIP means. The highest levels of dependency in ADL were reported by patients who were older, female, black, widowed, less educated, treated with in-center hemodialysis, had diabetes as the primary cause of ESRD, and/or reported more comorbidity. The partial effect of each factor on the dependent measures with adjustment for the seven other factors was assessed using analysis of covariance (ANCOVA). In the ADL analysis, sex, race, age, primary cause of kidney failure, and comorbidity were significant factors (probability values ranging from 0.05 for race to 0.0001 for sex, primary cause of ESRD, and comorbidity). The SIP physical dysfunction measure gave slightly different results. Race, age, primary cause of ESRD, comorbid status, and modality of treatment were significantly related to physical dysfunction (P less than 0.05 to P less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗

PubMed1989

Small-area variation in hospital discharge rates. Do socioeconomic variables matter?

Although numerous studies have been made of the determinants of small-area variation in hospital discharge rates, there is still disagreement about the role of socioeconomic factors. The lack of consensus stems, in part, from the difficulty in comparing results across studies that use different units and methods of analysis. Many of the studies using well-defined hospital service areas did not have the data needed to conduct a controlled analysis of the determinants of hospital utilization. Most of the studies that have performed controlled analyses have relied on larger geopolitical areas, which are not believed to capture self-contained health care systems. The study described here used a consistent set of data, three methods of analysis, and two units of analysis to test the importance of socioeconomic characteristics in explaining the variation in medical and surgical discharge rates in Michigan. Socioeconomic factors are found to be statistically significant determinants of the variation in both medical and surgical discharge rates, whether the method of analysis is simple correlations or multiple regressions, and whether the unit of analysis is the county or a well-designed hospital service area. These results suggest that previous small-area variation studies may have incorrectly concluded that socioeconomic characteristics do not explain differences in utilization rates.

Hospitals↗

PubMed1989

Variation in hospital admissions among small areas. A comparison of Maine and Michigan.

Analysis of age-adjusted hospital admission profiles among small geographic areas has shown marked variation in hospital admissions for both surgical and medical cases in areas ranging from Maine to Manitoba. Much of the work has been led by John Wennberg and has focused on rural areas. This study examines the degree of variation in hospital admissions in small areas in the state of Michigan to determine whether those diseases that demonstrated high variation in Maine also demonstrated the same degree of variation in Michigan. The data on the degree of variation in 111 modified diagnosis-related groups (M-DRGs) from the state of Maine were supplied by Dr. Wennberg. Using the same M-DRGs, we defined age-adjusted, population-based hospital admission rates for the lower peninsula of Michigan for 1980 among 60 previously defined hospital marked communities. The observed hospital discharge counts in each of the M-DRGs were compared to the expected counts in each of the 60 communities, where the expected count was based on an indirect age adjustment. Both the Maine and Michigan small area data were expressed by the M-DRG's systematic standard deviation in which random variation has been accounted for via a Poisson probability model. It was found that the systematic standard deviations of the M-DRGs in Maine and the M-DRGs in Michigan strongly correlated with a Spearman correlation coefficient of 0.71 (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Diagnosis-Related Groups↗

PubMed1989

Discontinuation of dialysis therapy as a cause of death.

Discontinuation of life-sustaining dialysis therapy led to death in 282 of 5,208 patients who started therapy for end-stage renal disease (ESRD) in Michigan during 1980-1985 with a follow-up through 1986. Based on life table estimates at 60 months after initiation of therapy, 9.4% of patients overall died due to termination of dialysis, 11% of females versus 8% of males (p = 0.02), 0.1-3.4% for ages less than or equal to 49 years versus 56% for greater than 80 years, 12% for white versus 4% for black patients (p less than 0.001) and 16% for diabetic ESRD patients (higher than any other group, p less than 0.05). The Cox regression model confirms these significant findings for race, diabetes and age, and reveals a significant 60% increase in overall withdrawals for the years 1980-1985 (1.10/year, p less than 0.02). A separate analysis of discontinuation of dialysis as the percentage of all 2,564 dialysis deaths in prevalence cases for 1980-1984 revealed an overall ratio of 8.9% with a significant difference for ages less than or equal to 64 versus greater than or equal to 65 (p less than 0.001), race (p less than 0.001) but not for prior transplant failure or continuous ambulatory peritoneal dialysis therapy. Whereas the results for age and diabetes were expected, the significant increase of dialysis withdrawal over time and the racial difference are unexplained by information available at the Michigan Kidney Registry and indicate the need for exploration by further studies.

Actuarial Analysis↗

PubMed1989

The role of pretransplant time and therapy on kidney graft survival.

1. The delay time between onset of ESRD and first cadaver kidney transplant varies considerably across patient subgroups. It is shortest for Whites and Asian Americans and longest for Blacks. Patients with blood type O and those highly sensitized have longer delays. 2. The effect of delay time on graft survival, while real and statistically significant, is quantitatively small. 3. Based on an analysis of a large national United States sample, CAPD therapy, compared to other forms of dialysis, does not have an adverse effect on 2-year graft survival.

Databases, Bibliographic↗

PubMed1989

Monoclonal antibody production in hollow fiber bioreactors using serum-free medium.

Murine hybridoma cells that produce monoclonal antibody directed against human fibronectin have been cultured in VITAFIBER II and VITAFIBER V hollow fiber bioreactors using defined, serum-free WRC 935 medium. During a two-week growth period, following inoculation of the bioreactors, the cells proliferated to an extent where the bioreactor was filled with cultured cells. Using a 5 sq. ft. VITAFIBER V bioreactor, over 15 grams of antibody were produced during the 40 days of the experiment. This antibody was greater than 95% IgG. During the production period, this packed mass of cells produced 579 +/- 15 mg IgG per day. Because the medium is formulated for air equilibration and high cell densities, WRC 935 medium is especially useful for production of gram quantities of monoclonal antibodies using continuous feed hollow fiber bioreactor cell culture systems.

Animals↗

PubMed1989

A comparison of employment rates of patients treated with continuous ambulatory peritoneal dialysis vs in-center hemodialysis (Michigan End-Stage Renal Disease Study).

This study examines factors associated with employment status in a stratified subsample of the Michigan End-Stage Renal Disease Study population. To reduce the variation in employment potential, the subsample consisted of nondiabetic patients aged 20 to 64 years. The patients were stratified on the basis of their treatment histories as follows: (1) treated by in-center hemodialysis only; (2) primarily treated by continuous ambulatory peritoneal dialysis; and (3) failed continuous ambulatory peritoneal dialysis, substituted by another form of dialysis. A significantly higher percentage of the patients undergoing stable continuous ambulatory peritoneal dialysis were in the labor force than were those undergoing in-center hemodialysis (27.4% vs 9.6%). Using logistic regression, even when adjusted for sex, race, age, education, marital status, primary diagnosis, and duration of end-stage renal disease, the stable continuous ambulatory peritoneal dialysis group was significantly more likely to be employed than the group undergoing either in-center hemodialysis only or the group that failed continuous ambulatory peritoneal dialysis.

Adult↗

PubMed1989

Patterns of surgical and nonsurgical hospital use in Michigan communities from 1980 through 1984.

Hospital discharge rates vary substantially among 60 communities in Michigan. (R2 = 90 percent and R2 = 85 percent of the systematic variance is explained by community effects for nonsurgical and surgical discharges, respectively.) The ranking of communities by discharge rates is stable over a five-year period (Spearman rho = 0.78 for nonsurgical discharges and 0.72 for surgical discharges). Surgical discharge rates decreased substantially (4 percent per year) over this time period, while nonsurgical rates showed no consistent pattern. Communities with exceptional discharge rates showed no substantial or significant regression toward the mean through the five-year study.

Adolescent↗

PubMed1988

Neurological abnormalities associated with remote occupational elemental mercury exposure.

We examined 502 subjects, 247 of whom had occupational elemental mercury exposures 20 to 35 years previously, to identify potential exposure-related neurological abnormalities. Few significant (p less than 0.05) differences existed between exposed and unexposed subjects. However, multiple linear regression analysis demonstrated several significant correlations between declining neurological function and increasing exposure as determined by urine mercury measurements from the exposure interval. Subjects with urine mercury peak levels above 0.6 mg/L demonstrated significantly decreased strength, decreased coordination, increased tremor, decreased sensation, and increased prevalence of Babinski and snout reflexes when compared with the remaining subjects. Furthermore, subjects with clinical polyneuropathy had significantly higher peak levels than normal subjects (0.85 vs 0.61 mg/L; p = 0.04), but not increased exposure duration (20.1 vs 20.8 quarters; p = 0.34), and 28% of subjects with peak levels above 0.85 mg/L had clinical evidence of polyneuropathy, compared with 10% of remaining subjects (p = 0.005). Although exposure was not age dependent, several neurological measures showed significant age-mercury interaction, suggesting that natural neuronal attrition may unmask prior exposure-related subclinical abnormalities.

Aging↗

PubMed1988

Predictive value of ventricular arrhythmias in resuscitated out-of-hospital cardiac arrest victims.

Twenty-four hour ambulatory electrocardiograms recorded in 103 survivors of out-of-hospital cardiac arrest were analyzed to find those characteristics of the ventricular premature complex (VPC) which provide the best combination of sensitivity, specificity, and predictive accuracy for subsequent mortality. VPC characteristics were grouped as: (1) frequent (greater than or equal to 25 h-1), (2)bigeminal, (3) multiform, (4) early coupled, (5) pairing, (6) repetitive greater than or equal to 2, (7) repetitive greater than or equal to 3, (8) repetitive greater than or equal to 6, (9) the combination of frequent and repetitive, or (10) complex defined as any multiform, early, bigeminal or repetitive VPC. In an average follow-up period of 43 months, 42 deaths occurred, 17 of which were classified as sudden. Each characteristic was a significant predictor for all causes of subsequent death except early coupled VPCs and repetitive VPCs greater than 6. None of the characteristics reached significance as predictors for sudden death. The number of repetitive VPCs when stratified to none, greater than or equal to 2 and greater than or equal to 3 successive VPCs correlated with mortality in an incremental fashion. The combination of frequent VPCs and repetitive VPCs provided the best combination of sensitivity, specificity and predictive accuracy for death from all causes within five years.

Arrhythmias, Cardiac↗

PubMed1988

Clinical characteristics and survival experience of out-of-hospital cardiac arrest victims without coronary heart disease.

Of 270 patients successfully resuscitated from out-of-hospital cardiac arrest, 16% had no evidence of coronary heart disease. In these 43 patients, other forms of heart disease were found in 81% (35/43): cardiomyopathy in 18 patients, valvular disease in six, congenital heart disease in two, and primary arrhythmia in nine. Seven patients had evidence of only pulmonary disease and one had pancreatitis as his precipitating event. Nineteen of the 43 patients (44%) had serum potassium less than 3.6 mEq l-1 in the initial blood sample after cardiac arrest. One- and two-year mortalities were 30% and 43%, respectively, for the group, which is similar to one-year (20%) and two-year (35%) mortalities of the 227 resuscitated patients with coronary heart disease. Patients who survive a sudden death experience and who have no evidence of coronary artery disease are a unique but heterogeneous group who usually have identifiable cardiac or pulmonary disease.

Cardiac Complexes, Premature↗

PubMed1988

Economic implications of workplace health promotion programs: review of the literature.

The conventional wisdom holds that workplace health promotion (HP) programs yield financial dividends, often generating cost savings. To examine the intellectual and empirical basis for this belief, we reviewed the literature on the economics of workplace HP programs. In general, in the literature published through early 1986, the claims of HP programs' profitability are based on anecdotal evidence or analyses seriously flawed in terms of assumptions, data, or methodology. Furthermore, certain aspects of the economics of HP programs have been virtually ignored. The dearth of sound evidence on the economic merits of workplace HP should not be interpreted as a negative assessment of the potential of such programs, however. Rather, it recommends a healthy skepticism in reading the literature and development of a new research-based body of understanding.

Back Injuries↗

PubMed1988

A new serum-free medium for monoclonal antibody production.

A new serum-free, defined-protein, medium for the growth of murine hybridoma cells and the production of monoclonal antibodies has been developed. Designated WRC 935 medium, this formulation supports the growth of hybridoma cells in higher numbers, and promotes better cell viabilities and increased monoclonal antibody levels compared to growth in DMEM supplemented with 10% fetal bovine serum or in a DMEM/F-12 serum-free mixture. In suspension cultures, WRC 935 medium typically promoted cell growth to densities over two million cells per milliliter. This medium also promoted the rapid growth of cells following their transfer from liquid nitrogen storage. WRC 935 medium is especially useful for high density cell culture production methods using hollow-fiber bioreactors. Hollow-fiber bioreactors using this medium produced antibody at an average rate of 11 mg/day, and the antibody concentration ranged from 10 to 40 mg/ml.

Animals↗

PubMed1987

Circadian incidence of premature rupture of the membranes in term and preterm births.

A highly circadian incidence of premature rupture of the fetal membranes was found in the Collaborative Perinatal Project data base. Among term deliveries without membranitis, the peak incidence of premature rupture of the membranes occurred at 3:00 AM, and the amplitude of a fitted sinusoid was 45%. Rupture hour was markedly influenced by latent interval and by membranitis. In the absence of membranitis, in term cases with a latent interval of less than three hours, rupture hour peaked at 2:00 AM, with an amplitude of 64%. Those with a latent interval of three to 35 hours peaked at 4:15 AM, with an amplitude of 37%. Those with 36 or more hours' latent interval showed little circadian variation. Preterm premature rupture of the membranes was also segregated into subgroups by latent interval. Preterm premature rupture of the membranes with a three- to 35-hour latent interval peaked at 4:00 AM, with an amplitude of 31%, similar to the corresponding term group. A circadian factor thus appears to cause most cases of premature rupture of the membranes in term and preterm births when membranitis is absent. The observed stratification by latent interval indicates that the mechanisms of premature rupture of the membranes may differ between the subgroups. With membranitis, the early-morning peak in premature rupture of the membranes was not statistically demonstrable in any of the term or preterm latent interval subgroups. This indicates that there may be unique rupture mechanisms associated with membranitis. The data in this study should assist efforts to classify premature rupture of the membranes and study its mechanisms.

Chorioamnionitis↗

PubMed1987

Circadian incidence of labor onset hour in preterm birth and chorioamnionitis.

Normal labor begins most frequently between midnight and 2 AM, presumably because of an unidentified circadian labor-activating mechanism. We used records of the Collaborative Perinatal Project to determine whether such a circadian mechanism is present with intrauterine growth retardation (IUGR) or preterm birth, and whether chorioamnionitis is associated with alternative patterns. In the absence of chorioamnionitis, both preterm births and term births with IUGR demonstrated nocturnal labor onset distributions like those of control term deliveries, which had a peak incidence at 1:45 AM and an amplitude of 35%. With chorioamnionitis, in contrast, there was a different circadian distribution of term labor onset hour, with a peak at 7:45 PM and a 32% amplitude. A similar trend was found among preterm births. These data suggest the presence of the normal nocturnal labor-activating mechanism in both growth-retarded term deliveries and a defined subset of preterm deliveries. Chorioamnionitis appears to be associated with a prominent, unidentified alternative labor-activating mechanism that is maximal in the evening.

Chorioamnionitis↗