Search PubMed⌕ Search

Biomedical subjects

D J Ballard

Publications and source records attributed to D J Ballard.

At least 55 records · Page 3Linked to original sources
PubMed1995

Variability in measurement of abdominal aortic aneurysms. Abdominal Aortic Aneurysm Detection and Management Veterans Administration Cooperative Study Group.

PURPOSE: The purpose of this study was to report interobserver and intraobserver variability of computed tomography (CT) measurements of abdominal aortic aneurysm (AAA) diameter and agreement between CT and ultrasonography observed in the course of a large, multicenter, randomized trial on the management of small AAAs. METHODS: CT measurements of AAA diameter from participating centers were compared with measurements made from the same scan by a central laboratory. Blinded central remeasurement of a randomly selected subset of these CT scans was used to assess intraobserver variability. Agreement between AAA measurements by CT and ultrasonography done within 30 days of each other was also assessed. RESULTS: For interobserver pairs of local and central CT measurements of AAA diameter (n = 806), the difference was 0.2 cm or less in 65% of pairs, but 17% differed by at least 0.5 cm. For intraobserver pairs of central CT remeasurements (n = 70), 90% differed by 0.2 cm or less, 70% were within 0.1 cm, and only one differed by 0.5 cm. Of 258 ultrasound-measured and central CT pairs, the difference was 0.2 cm or less in 44% and at least 0.5 cm in 33%. Ultrasound measurements were smaller than central CT measurements by an average of 0.27 cm (p < 0.0001). Local CT and ultrasound measurements showed a marked preference for recording by half centimeter. CONCLUSIONS: A high degree of precision is possible in CT measurement of AAA diameter, but this precision may not be obtained in practice because of differences in measurement techniques. Differences between imaging modalities increase variability further. Variations in AAA measurement of 0.5 cm or more are not uncommon, and this should be taken into account in management decisions. Efforts to reduce variation in measurement are warranted and might include (1) seeking agreement between surgeons and radiologists on a precise definition of AAA diameter, (2) limiting the number of radiologists who measure AAAs, and (3) use of calipers and magnifying glass for CT measurements.

Aged↗
PubMed1995

Ownership and utilization of MR imagers in the Commonwealth of Virginia.

PURPOSE: To assess distribution, operation, and ownership of magnetic resonance (MR) imagers in Virginia in 1991. MATERIALS AND METHODS: Questionnaires regarding ownership, location, hours of operation, annual throughput, sources and amounts of revenue, and expenses were mailed to identified providers. Data, specifically regarding ownership and location, were analyzed. RESULTS: Staff from 95% of MR facilities responded. Most facilities were located in and around major metropolitan areas. Population density per imager ranged from one per 76,000 to one per 222,000 persons. Imagers in larger metropolitan areas were operated for longer hours with higher revenues and greater expenses than were those in lower-population-density areas. Imagers owned by physicians in a position to self-refer had the highest patient throughput, the most revenue, and a much lower percentage of revenues from Medicare and Medicaid than did other ownership types. CONCLUSION: Patient access to MR services in Virginia is inhomogeneous. Important aspects of utilization are location and ownership. Ownership by physicians who can self-refer is associated with higher use, greater overall revenues, and less service to the poor and elderly.

Costs and Cost Analysis↗
PubMed1995

Risk of stroke with mitral valve prolapse in population-based cohort study.

BACKGROUND AND PURPOSE: The purpose of this study was to clarify whether mitral valve prolapse increases the subsequent risk of stroke. METHODS: A historical cohort study was conducted on 1079 residents of Olmsted County, Minnesota, who had an initial echocardiographic diagnosis of mitral valve prolapse between 1975 and 1989 without prior stroke or transient ischemic attack and who were followed up for first stroke occurrence. RESULTS: There was an overall twofold increase in the incidence of stroke among individuals with mitral valve prolapse relative to the reference population (standardized morbidity ratio, 2.1; 95% confidence interval, 1.3 to 3.2). Sex, duration of follow-up from the diagnosis of mitral valve prolapse, or calendar year of initial diagnosis did not modify the association. Within the cohort of patients who were at least 35 years old at diagnosis of mitral valve prolapse, a time-dependent proportional-hazards multivariate model and a person-years analysis revealed that age, ischemic heart disease, congestive heart failure, and diabetes mellitus were important determinants for stroke when person-years of observation after mitral valve replacement were excluded. Among seven persons with mitral valve replacement, three strokes occurred in 24 person-years of follow-up. For those with an auscultatory diagnosis of mitral valve prolapse only as the indication for echocardiography (44%), the risk of stroke relative to the population was 1.0 (95% confidence interval, 0.2 to 2.9); for those with another cardiac diagnosis, the standardized morbidity ratio was 2.5 (95% confidence interval, 1.5 to 4.0). CONCLUSIONS: Individuals with uncomplicated mitral valve prolapse did not have an increased risk of stroke, although a small increase in the risk may not have been detected.

Adult↗
PubMed1995

A data-driven approach to improving the care of in-center hemodialysis patients.

Health care providers, patients, the end stage renal disease (ESRD) networks, and HCFA have developed the ESRD Health Care Quality Improvement Program (HCQIP) in an effort to assess and improve care provided to ESRD patients. Currently, the ESRD HCQIP focuses on collecting information on quality indicators (QIs) for treatment of anemia, delivery of adequate dialysis, nutritional status, and blood pressure control for adult in-center hemodialysis patients. QIs were measured in a national probability sample of ESRD patients, and interventions and evaluations of the interventions are beginning. The ESRD HCQIP illustrates a way to mobilize the strengths of the public and private sectors to achieve improved care for special populations.

Adult↗
PubMed1994

Influence of coronary heart disease on morbidity and mortality after lower extremity revascularization surgery: a population-based study in Olmsted County, Minnesota (1970-1987).

OBJECTIVES: The aim of this study was to evaluate the short- and long-term postoperative cardiac outcome of patients undergoing lower extremity revascularization surgery in a geographically defined patient group. BACKGROUND: Among patients with peripheral vascular disease, cardiac events have an important effect on long-term outcome after peripheral vascular surgery. However, long-term outcome is poorly documented. METHODS: We examined the entire community medical records of 173 residents of Olmsted County, Minnesota, who underwent peripheral artery bypass surgery between 1970 and 1987 and were followed up to January 1, 1991. Patients were allocated to subgroups of 60 patients with and 106 patients without overt coronary artery disease. RESULTS: There were no significant differences in perioperative death, myocardial infarction or stroke between subgroups at 30 days after operation. The 5- and 10-year Kaplan-Meier survival rate after operation was 77% and 51% in those without and 54% and 24% in those with overt coronary artery disease (p < 0.001), respectively. For both groups, survival was significantly poorer than that expected for an age- and gender-matched group. Patients undergoing aortoiliac surgery were more likely to be alive at 10 years than those undergoing femoropopliteal surgery (47% vs. 28%, p = 0.001). The 5-year cumulative incidence of cardiac events was greater in those with overt coronary artery disease (50% vs. 28%, p = 0.003). In multivariable analysis, age, coronary artery disease and diabetes were independent predictors of death. CONCLUSIONS: Coronary events are the most important cause of long-term morbidity and mortality after peripheral vascular surgery. Patients without overt coronary artery disease are at significant risk for long-term cardiac events.

Arteriosclerosis↗
PubMed1994

Long-term survival after pacemaker implantation for heart block in patients > or = 65 years.

Permanent pacing can prevent recurrent symptoms and reduce mortality in elderly patients with symptomatic high-degree atrioventricular (AV) block. However, long-term survival with respect to comparable control subjects has not been well defined. In our study, relative long-term survival and prognostic predictors after permanent pacemaker implantation for symptomatic high-degree AV block were assessed among all residents of Olmsted County, Minnesota, who were > or = 65 years old. Of the 154 patients, 77 were men and 77 were women (mean age 80 +/- 7 years). Follow-up was 0.1 to 19.8 years (mean 4.2 +/- 2.8). Sixty-nine patients had isolated AV block and 85 had coexisting heart disease. Observed survival at 1, 3, 5, and 10 years was 85%, 68%, 52%, 21%, and 72%, 50%, 31%, 11% for patients with isolated AV block and patients with coexisting heart disease, respectively (p = 0.006). Observed survival in patients 65 to 79 years old with isolated AV block was comparable to age- and sex-matched cohorts (p = 0.53), but in patients aged > or = 80 years, it was less than that for control subjects (p = 0.014). In patients with coexisting heart disease, observed survival was less than that for control subjects in patients 65 to 79 years old (p < 0.001) and > or = 80 years (p < 0.001). Multivariate analysis identified congestive heart failure, chronic obstructive pulmonary disease, age, syncope, insulin-dependent diabetes mellitus, and male gender as independent predictors of increased mortality.

Age Factors↗
PubMed1994

Prognostic value of exercise radionuclide angiography in a population-based cohort of patients with known or suspected coronary artery disease.

Five hundred thirty-six residents of Olmsted County, Minnesota, who underwent supine rest and exercise radionuclide angiography because of known or suspected coronary artery disease, were followed for a median of 46 months to determine the prognostic value of exercise radionuclide angiography in a community population who generally did not undergo coronary angiography. There were 71 persons who experienced a new cardiac event (the initial events were cardiac death and nonfatal myocardial infarction in 26 and 45 persons, respectively). A proportional-hazards model identified 4 independent predictors of cardiac events: exercise ejection fraction (p < 0.001), exercise heart rate (p < 0.001), and age (p = 0.04). Four-year infarct-free survival was 98% for the 152 patients with a peak exercise heart rate at or above the median (122 beats/min) and an exercise ejection fraction at or above the median (0.58). In the 150 patients with a peak exercise heart rate < 122 beats/min and an exercise ejection fraction < 0.58, 4-year infarct-free survival was 68%. When this population-based cohort was compared with a referral case series previously reported from our institution, these population-based patients were significantly more likely to be men, to have typical angina, to have higher exercise heart rates and exercise ejection fractions, and were less likely to be receiving beta-receptor antagonist therapy. At each level of exercise ejection fraction, the population-based patients had a slightly but insignificantly greater risk than referral patients for subsequent cardiac events. These population-based data provide strong evidence of the prognostic value of exercise radionuclide angiography in community practice.

Age Factors↗
PubMed1994

The contribution of non-insulin-dependent diabetes to lower-extremity amputation in the community.

BACKGROUND: Despite the significant public health burden of lower-extremity amputations in diabetes mellitus, few data are available on the epidemiology of lower-extremity amputations in diabetes mellitus in the community setting. METHODS: A retrospective incidence cohort study based in Rochester, Minn, was conducted. RESULTS: Among the 2015 diabetic individuals free of lower-extremity amputation at the diagnosis of diabetes mellitus, 57 individuals underwent 79 lower-extremity amputations (incidence, 375 per 100,000 person-years; 95% confidence interval, 297 to 467). Among the 1826 patients with non-insulin-dependent diabetes mellitus, 52 underwent 73 lower-extremity amputations, and the subsequent incidence of lower-extremity amputation among these residents was 388 per 100,000 person-years (95% confidence interval, 304 to 487). Of the 137 insulin-dependent diabetic patients, four subsequently underwent five lower-extremity amputations (incidence, 283 per 100,000 person-years; 95% confidence interval, 92 to 659). Twenty-five years after the diagnosis of diabetes mellitus, the cumulative risk of one lower-extremity amputation was 11.2% in insulin-dependent diabetes mellitus and 11.0% in non-insulin-dependent diabetes mellitus. When compared with lower-extremity amputation rates for Rochester residents without diabetes, patients with non-insulin-dependent diabetes mellitus were nearly 400 times more likely to undergo an initial transphalangeal amputation (rate ratio, 378.8) and had almost a 12-fold increased risk of a below-knee amputation (rate ratio, 11.8). In this community, more than 60% of lower-extremity amputations were attributable to non-insulin-dependent diabetes mellitus. CONCLUSIONS: These population-based data document the magnitude of the elevated risk of lower-extremity amputation among diabetic individuals. Efforts should be made to identify more precisely risk factors for amputation in diabetes and to intervene in the processes leading to amputation.

Amputation, Surgical↗
PubMed1994

Design of the abdominal aortic Aneurysm Detection and Management Study. ADAM VA Cooperative Study Group.

PURPOSE: This study describes the design of an ongoing randomized trial intended to determine which of two strategies is superior for managing small abdominal aortic aneurysms (AAA). METHODS: Patients aged 50 to 79 years with AAA 4.0 to 5.4 cm in diameter as determined by computed tomography (CT) who are not at high surgical risk are randomized to either repair of the AAA, called "immediate surgery," or follow-up of the AAA with ultrasonography or CT every 6 months, reserving surgery for those aneurysms that enlarge to 5.5 cm, enlarge rapidly, or become symptomatic, called "selective surgery." RESULTS: The primary outcome measure is all-cause death, and secondary outcome measures are AAA-related death, morbidity, and general health status. The study design calls for 1350 patients to be randomized and monitored for a mean of 5 years. A second objective of the study is to accurately define the prevalence and risk factors for AAA with use of information from the large screening program established to detect AAA for recruitment into the randomized trial. CONCLUSIONS: By the end of 1993, 38,697 patients had been screened with ultrasonography, accounting for about three fourths of new randomizations, and 330 patients had been enrolled (70% of the target rate).

Aged↗
PubMed1994

Liver iron stores in patients with non-insulin-dependent diabetes mellitus.

BACKGROUND: Iron overload such as that in idiopathic hemochromatosis is a well-established, albeit rare, cause of non-insulin-dependent diabetes mellitus (NIDDM). Most patients with NIDDM have no recognized cause of their disease. Investigators have proposed that subclinical iron overload may cause diabetes mellitus in a substantial number of patients with NIDDM. OBJECTIVE: The aim of the current study was to evaluate hepatic iron stores in autopsy specimens from a group of community residents with NIDDM. METHODS: Fifteen patients with NIDDM and 17 age-matched control subjects were identified from a review of medical records of decreased residents of Olmsted County, Minnesota. Formalin-fixed liver tissue was analyzed for iron concentration by flameless atomic absorption spectrophotometry, and distribution of hepatic iron was determined histochemically. RESULTS: No significant difference was found in either the distribution or the mean amount of hepatic iron between the diabetic and the control group (1,303 versus 1,349 micrograms Fe/g dry weight; P = 0.87). Thus, the mean difference was -46 micrograms Fe/g dry weight (confidence interval, -631 to 540). CONCLUSION: Because hepatic iron quantification is the definitive means of assessing total body iron stores, our results suggest that NIDDM is typically not associated with a substantial level of iron overload.

Aged↗
PubMed1994

The RAND/AMA/AMCC Clinical Appropriateness Initiative: insights for multi-site appropriateness studies derived from the abdominal aortic aneurysm surgery project.

This paper describes a collaborative effort among several organizations in the United States (the RAND/American Medical Association (AMA/Academic Medical Center Consortium (AMCC) Clinical Appropriateness Initiative) and presents, as an illustrative example, one of the four projects of this initiative, the abdominal aortic aneurysm surgery project that was directed by the author. The Clinical Appropriateness Initiative was conceived as a long-term program to develop and maintain a current set of clinical practice guidelines that would play an integral role in enhancing the quality of care delivered in the USA. However, several problems were encountered in its inception that ultimately resulted in early termination of the project. The primary reason for the demise of the abdominal aortic aneurysm surgery project and the other components of the Clinical Appropriateness Initiative was failure to enlist the support of AMCC clinical leaders prior to initiating the project. Numerous opportunities to optimize the generation and implementation of the practice guidelines for the intention of improving health care quality were identified during the conduct of the Clinical Appropriateness Initiative. Health care quality improvement initiatives throughout Europe may benefit from the RAND/AMA/AMCC experience and have the ability to address many of the scientific and policy issues raised by the Clinical Appropriateness Initiative.

Academic Medical Centers↗
PubMed1994

Referral selection bias in the Medicare hospital mortality prediction model: are centers of referral for Medicare beneficiaries necessarily centers of excellence?

OBJECTIVE: Although the Health Care Financing Administration (HCFA) uses Medicare hospital mortality data as a measure of hospital quality of care, concerns have been raised regarding the validity of this concept. A problem that has not been fully evaluated in these data is the potential confounding effect of illness severity factors associated with referral selection and hospital mortality on comparisons of risk-adjusted hospital mortality. We address this issue. DATA SOURCES AND STUDY SETTING: We analyzed the 1988 Medicare hospitalization data file (MEDPAR). We selected data on patients treated at the two Mayo Clinic-associated hospitals in Rochester, Minnesota, and a group of seven other hospitals that treat many patients from large geographic areas. These hospitals have had observed mortality rates substantially lower than those predicted by the HCFA model for the period 1987-1990. STUDY DESIGN: Using the multiple logistic regression model applied by HCFA to the 1988 data, we evaluated the relationship between distance from patient residence to the admitting hospital and risk-adjusted hospital mortality. PRINCIPAL FINDINGS: Among patients admitted to Mayo Rochester-affiliated hospitals, residence outside Olmsted County, Minnesota was independently associated with a 33 percent lower 30-day mortality rate (p < .001) than that associated with residence in Olmsted County. When patients at Mayo hospitals were stratified by residence (Olmsted County versus non-Olmsted County), the observed mortality was similar to that predicted for community patients (9.6 percent versus 10.2 percent, p = .26), whereas hospital mortality for referral patients was substantially lower than predicted (5.0 percent versus 7.5 percent, p = < .001). After incorporation of the HCFA risk adjustment methods, distance from patient residence to the hospitals was also independently associated with mortality among the Mayo Rochester-affiliated hospitals and seven other referral center hospitals. CONCLUSIONS: The HCFA Medicare hospital mortality model should be used with extreme caution to evaluate hospital quality of care for national referral centers because of residual confounding due to severity of illness factors associated with geographic referral that are inadequately captured in the extant prediction model.

Aged↗
PubMed1993

Incidence of ulcerative keratitis in a defined population from 1950 through 1988.

OBJECTIVE: To determine the incidence of ulcerative keratitis and to assess trends in risk factors leading to ulcerative keratitis. DESIGN: Retrospective incidence cohort study. SETTING: General community. PATIENTS: Population-based sample of residents of Olmsted County, Minnesota, in the 39-year period between 1950 and 1988. MAIN OUTCOME MEASURE: Cases of ulcerative keratitis. RESULTS: One hundred forty-one cases of ulcerative keratitis were diagnosed among 131 residents (64 men and 67 women) of Olmsted County. The mean annual age-adjusted incidence per 100,000 people was 5.3 (95% confidence interval, 4.4 to 6.2). A 435% increase in the incidence of ulcerative keratitis was observed in Olmsted County residents from the 1950s (2.5 per 100,000 people) to the 1980s (11.0 per 100,000 people) (P = .001). The cases of ulcerative keratitis associated with contact lens wear increased from 0% in the 1950s and 1960s to 32% in the 1970s and 52% in the 1980s. CONCLUSION: The incidence of ulcerative keratitis has increased significantly in this community. Contact lens wear was the most important risk factor for the development of ulcerative keratitis during the last decade.

Adolescent↗
PubMed1993

Natural history of idiopathic dilated cardiomyopathy: effect of referral bias and secular trend.

OBJECTIVES: The current study was designed to determine the effect of secular trend and referral bias on the natural history of idiopathic dilated cardiomyopathy. BACKGROUND: In a previous study of 104 patients with idiopathic dilated cardiomyopathy conducted in a referral population at the Mayo Clinic between 1960 and 1973, the 1- and 5-year mortality rates were 31% and 64%, respectively. A recent study of 40 patients with idiopathic dilated cardiomyopathy conducted in a population-based cohort at the Mayo Clinic between 1975 and 1984 reported 1- and 5-year mortality rates of 5% and 20%, respectively. We hypothesized that improvements in diagnosis and therapy have occurred since the original referral cohort was described and that these improvements have altered the apparent natural history of the disease. We refer to this effect as secular trend. Alternatively, the presence of more advanced disease in the referral population (referral bias) may also contribute to the differences in survival. METHODS: Two sequential referral populations with idiopathic dilated cardiomyopathy seen at the Mayo Clinic between 1976 and 81 (n = 85) and 1982 and 1987 (n = 137) were identified. Outcome was compared between these cohorts and the 1960-1973 referral cohort to examine the effect of secular trend. Outcomes were compared with that of the population-based cohort to examine the effect of referral bias. RESULTS: Survival in the 1976-1981 referral cohort did not differ from that in the 1960-1973 referral cohort, suggesting little impact of secular trend during these time periods. Survival in the more recent 1982-1987 referral cohort was significantly better than that in the earlier referral cohorts, suggesting that improvements in diagnosis and treatment in the 1980s altered the natural history of idiopathic dilated cardiomyopathy. Survival in the 1982-1987 referral cohort was still worse than that of the population-based cohort, suggesting an effect of referral bias on studies of the natural history of idiopathic dilated cardiomyopathy. CONCLUSIONS: The current study demonstrates that secular trend and referral bias affect the apparent natural history of idiopathic dilated cardiomyopathy. Survival in referral patients with this disease is significantly better than previously described.

Bias↗
PubMed1993

The incidence and prevalence of congestive heart failure in Rochester, Minnesota.

Although congestive heart failure is a fairly common clinical syndrome and the societal costs associated with its care are high, relatively little is known about the incidence or prevalence of the condition in the community. Using the resources of the Rochester Epidemiology Project, we identified all 46 persons 0 through 74 years of age who had a new diagnosis of congestive heart failure during 1981 and all 113 persons with a prevalent diagnosis on Jan. 1, 1982, in the city of Rochester, Minnesota. After confirming the diagnosis in the medical record by using criteria similar to those in the Framingham study, we found the annual incidence of congestive heart failure to be 110 per 100,000 after adjusting for age. Incidence rates were higher among male than among female study subjects (157 versus 71 per 100,000). In both male and female subjects, the incidence generally increased with advancing age, reaching 1,618 per 100,000 and 981 per 100,000, respectively. Prevalence rates on Jan. 1, 1982, demonstrated similar patterns. Overall, the prevalence of congestive heart failure was higher among male than among female subjects (327 versus 214 per 100,000) and increased exponentially with advancing age, reaching almost 3% in both sexes. Survival after a diagnosis of congestive heart failure was extremely poor, with only 80% alive at 3 months and 66% at 1 year. These data underscore the effect of congestive heart failure in the community and provide estimates of the number of persons who might benefit from early intervention.

Adolescent↗
PubMed1993

How can schools help children from homeless families?

Families represent the fastest growing subgroup among the homeless in America. Most homeless families are headed by women who lack high school diplomas, have poor work skills, little job training, and are long-term users of Aid to Families with Dependent Children (AFDC). The average homeless family is comprised of two to three children, most of whom are younger than age five. These children suffer from a number of acute and chronic health problems. Once in school, these children often experience developmental and academic delays which increase the potential for school dropout. School districts must address the health and academic challenges these children bring to school. Measures include forming a community-based task force, working with homeless shelters in addressing needs of these families, increasing awareness of faculty and staff, and developing specific classroom/school environment strategies to encourage these children to succeed. Opportunities for involvement by teachers, counselors, and school nurses are noted, and seven strategies to help the homeless child in school are offered.

Child↗