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Biomedical subjects

D J Ballard

Publications and source records attributed to D J Ballard.

At least 73 records · Page 4Linked to original sources
PubMed1993

A population study of the natural history of Wolff-Parkinson-White syndrome in Olmsted County, Minnesota, 1953-1989.

BACKGROUND: Virtually all natural history studies of Wolff-Parkinson-White (WPW) syndrome have been case series and, as such, have been constrained by referral biases, skewed age and sex distributions, or brief follow-up periods. The purpose of our study was to examine the natural history, the development of arrhythmias, and the incidence of sudden death in an entire cohort of pediatric and adult WPW patients from a community-based local population. METHODS AND RESULTS: We identified 113 residents of Olmsted County, Minnesota, during the period 1953-1989 using the centralized records-linkage system provided by the Mayo Clinic and the Rochester Epidemiology Program Project. Medical records and ECGs were reviewed to confirm the diagnosis and to establish pathway location by ECG criteria. Follow-up, via record review and telephone interview, was complete in 95% of subjects through 1990. The incidence of newly diagnosed cases was approximately four per 100,000 per year. Preexcitation was not present on the initial ECG of 22% of the cohort. Approximately 50% of the population was asymptomatic at diagnosis, with 30% subsequently having symptoms related to arrhythmia at follow-up. Two sudden cardiac deaths (SCD) occurred over 1,338 patient-years of follow-up, yielding an overall SCD rate of 0.0015 (95% confidence interval, 0.0002-0.0054) per patient-year. No SCD occurred in patients asymptomatic at diagnosis. CONCLUSIONS: The incidence of sudden death in a local community-based population is low and suggests that electrophysiological testing should not be performed routinely in asymptomatic patients with WPW syndrome. Nevertheless, young, asymptomatic patients, particularly those < 40 years old, should return for medical follow-up should symptoms develop.

Adolescent↗
PubMed1993

The Stroke Prevention Patient Outcomes Research Team. Goals and methods.

BACKGROUND AND PURPOSE: The aim of the present study, based at Duke University and involving 14 other institutions, is to identify the most appropriate and cost-effective clinical strategies for prevention of ischemic (thrombotic or embolic) stroke in high-risk individuals and to design and test an intervention to disseminate this information to providers and the public. METHODS: The study uses (1) secondary data from literature review, Medicare claims, and population-based data from three epidemiological studies and (2) primary data generated in national physician and patient surveys and in demonstration trials. Phases I through III involve data collection and analysis using a decision/cost-effectiveness model and consensus development methods. Phase IV includes intervention in physicians' practice patterns. Data is collected by literature survey and abstraction, review of medical records, claims analysis, and patient and physician surveys. CONCLUSIONS: A structured decision model and a well-defined clinical focus provide a successful organization for a PORT on stroke prevention.

Cerebrovascular Disorders↗
PubMed1993

Early and late outcome of surgical repair for small abdominal aortic aneurysms: a population-based analysis.

PURPOSE: Whether small abdominal aortic aneurysms (AAAs) (< or = 5 cm in diameter) should be repaired early to enhance late survival remains controversial. Long-term population-based data on the surgical outcome for small AAAs may help to establish practice guidelines until randomized clinical trials are completed. METHODS: To examine an entire community experience with small AAAs, we conducted a population-based analysis of the recognition, reasons for operation, perioperative mortality rates, and late survival in Olmsted County, Minnesota. RESULTS: The incidence of recognized small AAAs increased thirtyfold during a 30-year period. The propensity to repair small AAAs also increased during the same period. Eventually one third of small AAAs were repaired. The primary reasons for surgical consultation and operation were presence of the aneurysm (49%), expansion on serial examination (28%), nonspecific abdominal or back symptoms (18%), and excessive patient anxiety about the aneurysm (5%). Community operative mortality rates for small AAAs were low (2.6%) compared with those for large aneurysms (5.5%) (p = 0.65). However, the observed 5-year survival rate for the group undergoing repair of small aneurysms was 62%, which was significantly less than the 83% expected survival for the general population (p < 0.05). Relative survival for the operated small and large aneurysms was similar. The primary cause of death for both groups was myocardial infarction. CONCLUSIONS: The results of our population-based analysis indicate that early operative results for elective repair of small AAAs are excellent, but late survival remains significantly impaired by coronary heart disease. Consequently, our data question whether early repair of small AAAs will enhance late survival. Until randomized clinical trials on management of small AAAs are completed, most small AAAs should be monitored for expansion and operated on electively when they approach or enter the range of 5 to 6 cm in good-risk patients.

Age Factors↗
PubMed1992

The clinical course of idiopathic dilated cardiomyopathy. A population-based study.

OBJECTIVE: To describe the prognosis of individuals with idiopathic dilated cardiomyopathy in a population-based sample and to compare this with the prognosis of patients in a previous referral center case series of idiopathic dilated cardiomyopathy. DESIGN: Cohort study. SETTING: Population-based in Olmsted County, Minnesota. PATIENTS: Forty residents of Olmsted County, Minnesota with idiopathic dilated cardiomyopathy initially diagnosed between 1975 and 1984 who were followed through 1 July 1989 and 104 patients from a Mayo Clinic referral case series from 1960 to 1973. MEASUREMENTS: Survival for the population-based cohort at 1 year and 5 years. RESULTS: Survival at 1 year differed dramatically between the population-based cohort and the referral case series at 1 year (95% compared with 69%, respectively) and at 5 years (80% compared with 36%, respectively) (P less than 0.001). Long-term survival for the population-based cohort was nonetheless impaired when compared with an age- and sex-matched cohort, that is, the 1980 Minnesota white population (8-year survival: observed, 58% compared with expected, 83%; P less than 0.001). Among community patients, older age (adjusted Cox model hazard ratio for 10-year increase in age, 1.59; 95% CI, 1.08 to 2.35) and lower left ventricular ejection fraction (adjusted hazard ratio for 10% decrease, 1.90; CI, 1.04 to 3.50) were independently associated with impaired survival. CONCLUSIONS: These population-based data challenge the clinical perception of the clinical course of idiopathic dilated cardiomyopathy based on referral practice prognostic studies and suggest that the clinical course of this condition may be more favorable than previously recognized.

Cardiomyopathy, Dilated↗
PubMed1992

Incidence of enucleation in a defined population.

We conducted a population-based study of long-term trends in the incidence of enucleation. From 1956 through 1988, enucleation was performed on 99 residents (55 males and 44 females) of Olmsted County, Minnesota. The mean annual age-adjusted incidence per 100,000 population for males (5.17) was 50% greater than that for females (3.49; P = .04). An increase in the enucleation rate was noted with increasing age (P = .001), with the highest incidence in patients who were 70 to 79 years of age. A decrease in the incidence of enucleation over time (P = .002) was observed in Olmsted County residents who were at least 40 years of age and was caused primarily by the decreasing incidence of neovascular glaucoma and tumor-related enucleations. The incidence of traumatic enucleations did not significantly decrease (P = .25) over this three-decade study period.

Adolescent↗
PubMed1992

Long-term survival and sequelae after surgical management of invasive cervical carcinoma diagnosed at the time of simple hysterectomy.

From 1956 to 1988, 27 women (median age, 60 years) found to have occult invasive carcinoma of the cervix at total hysterectomy underwent radical reoperation consisting of radical parametriectomy, upper vaginectomy, and pelvic lymphadenectomy. Residual disease was present at reexploration in 4 (15%) of the 27 patients: in the pelvic lymph nodes in 2, in the parametrium in 1, and in the vagina and a para-aortic node in 1. All patients were followed a minimum of 18 months; there were no deaths within 3 months of operation. However, 2 (7%) of the 27 patients developed ureterovaginal fistulas. Recurrent disease was observed in 6 (22%) of the patients: 2 had successful salvage procedures, and 4 died of disease, all within 4 years of reoperation. Recurrence correlated with the presence of residual disease at reoperation and with nonsquamous histologic findings. At a median follow-up of 8.4 years, 23 of the 27 patients were alive and disease-free. The 5-year absolute survival estimate (Kaplan-Meier) was 82%. Radical reoperation can be performed safely in selected patients who have early-stage invasive carcinoma of the cervix at the time of total hysterectomy with the expectation of an acceptable rate of long-term disease-free survival.

Adenocarcinoma↗
PubMed1992

Influence of coronary heart disease on morbidity and mortality after carotid endarterectomy: a population-based study in Olmsted County, Minnesota (1970-1988)

To evaluate the prognostic importance of coronary artery disease among patients undergoing carotid endarterectomy, 177 residents of Olmsted County, Minnesota who underwent carotid endarterectomy during the period 1970 through 1988 were followed up to July 1, 1989. Patients were stratified as to the presence (n = 64) or absence (n = 93) of overt coronary artery disease or prior myocardial revascularization (n = 20) at the time of endarterectomy. At 30 days after carotid endarterectomy, there were no significant differences between patients with or without coronary artery disease in the occurrence of death, myocardial infarction or stroke. Kaplan-Meier estimate of 8-year relative survival after carotid endarterectomy (assessed as a percent of survival in age- carotid endarterectomy (assessed as a percent of survival in age- and gender-matched control subjects) was 89% in those without and 75% in those with overt coronary artery disease. Of the 59 total deaths, 29 (49%) had a cardiac cause and 4 (7%) were due to stroke (p less than 0.0001). The cumulative incidence of a cardiac event at 8 years after carotid endarterectomy was greater in those with than in those without overt coronary artery disease (61% vs. 25%, p less than 0.0001). In multivariable analysis, uncorrected coronary artery disease and diabetes were the only independent predictors of subsequent cardiac events, whereas age was the only independent predictor of death. These population-based data suggest that carotid endarterectomy can be safely undertaken in patients with stable coronary artery disease. In long-term follow-up of these patients, coronary rather than cerebral vascular disease is the most frequent cause of morbidity and mortality. Thus, these data lend strong support to the concept of early identification and management of coronary artery disease in patients undergoing carotid endarterectomy.

Cohort Studies↗
PubMed1992

The Olmsted County Benchmark Project: primary study findings and potential implications for corporate America.

Since 1965, expenditures for medical care in the United States have increased 10-fold. As a result, corporate outlays for health benefits have skyrocketed. Employers have instituted various cost-containment measures based in part on reports of wide variations in rates of utilization and the assumption that unnecessary or inappropriate utilization of medical care contributes to increasing costs. Frequently, however, employers lack adequate means for identifying sources of variation or for evaluating its appropriateness. In this article, we report on a project in which hospital utilization among several US corporate populations was compared with that for a geographically defined benchmark population to assist employers in the assessment of their rates of utilization and expenditures and to identify specific areas that merit further investigation. Our findings illuminate the difficulties in constructing valid rates from medical-care claims data and emphasize potential biases due to problems of comparability between populations. We also address the potential value of such comparison for helping corporations identify areas in which cost-containment efforts may be most effective and yet not jeopardize the quality of medical care.

Adolescent↗
PubMed1992

Predictors of outcome after percutaneous endoscopic gastrostomy: a community-based study.

Percutaneous endoscopic gastrostomy (PEG) is used to provide nutrition for patients who are unable to eat but have a functionally intact gut. Clinical guidelines for PEG are uncertain and have been derived mainly from referral practices. We performed a population-based cohort study in 97 residents of Olmsted County, Minnesota, referred for PEG between January 1982 and December 1988 to determine complications, duration of tube feeding, and survival. Follow-up continued until death or February 1990. Inpatient and outpatient records were reviewed to determine indications, comorbid conditions, level of consciousness, and limitations in activities of daily living. Outcomes determined after referral for PEG included type and number of complications, tube removal, and survival. Statistical methods used included Kaplan-Meier and proportional hazards regression analyses. PEG placement was successful in 94% of patients. Although complications occurred in 70% of patients, they usually were minor (88%) and most occurred within 3 months. In 24 patients, tubes were removed because eating was resumed. The probability of surviving 30 days, 1.5 years, and 4 years after referral for PEG was 78%, 35%, and 27%, respectively. The major causes of death within and after 30 days were pneumonia, heart disease, and vascular disease of the central nervous system. An increased risk of death after referral for PEG placement was associated with older age, male gender, diabetes, and specific indications for PEG. If validated in other population-based studies, these predictors of survival after referral for PEG placement could be used to identify patients with a low probability of survival who may not benefit from PEG.

Adolescent↗
PubMed1992

Contribution of a measure of disease complexity (COMPLEX) to prediction of outcome and charges among hospitalized patients.

Attention has been focused on the need to adjust hospital reimbursement and outcomes of hospital care for level of illness. Extant measures of disease severity, however, fail to consider the contribution of disease complexity. We developed an easily retrievable measure of disease complexity (COMPLEX) by modifying an existing severity system, computerized Disease Staging. The contribution of COMPLEX (the number of body systems affected with a Disease Staging score of 2 or more) to the prediction of outcome was assessed in two studies: (1) a population-based analysis of readmission and mortality after hospitalization and (2) an analysis of hospital charges among patients who were in an intensive-care unit. The amount of variation in mortality explained by factors included in the Health Care Financing Administration model was significantly improved when COMPLEX was added to the model (adjusted odds ratio per body system, 1.83; 95% confidence interval, 1.61 to 2.08). A significant association was also observed between COMPLEX score and hospital readmission after adjustment for age, sex, case-mix, and disease severity (adjusted odds ratio, 1.31; 95% confidence interval, 1.20 to 1.44). When COMPLEX was added to case-mix and disease severity in a model for predicting hospital charges, the percentage of variation in hospital charges explained by the model increased from 25% to 38%. These findings demonstrate the important contribution of disease complexity to the analysis of outcome of medical care and utilization of resources. Outcome or reimbursement models that do not incorporate disease complexity may negatively affect institutions with a high proportion of patients who have complex conditions.

Aged↗
PubMed1992

Body mass index and the initial manifestation of coronary heart disease in women aged 40-59 years.

A population-based case-control study was conducted to evaluate body mass as a coronary heart disease (CHD) risk factor among women 40-59 years of age. Cases were women aged 40-59 whose first manifestation of CHD was angina (No. = 133), nonfatal myocardial infarction (No. = 90), and sudden unexpected death (No. = 18) during 1960-1982. Two randomly selected controls were matched on age and time of the initial disease manifestation of the case. The adjusted relative risk for weight and body mass index respectively demonstrated a moderate association with all CHD as well as with angina, but no association with definite CHD (myocardial infarction or sudden unexpected death). To determine if the observed association between body mass index and angina was possibly attributable to differential misclassification bias (i.e. obese women were, in contrast to non-obese women, preferentially labelled as having coronary artery disease) data for angina were stratified by confirmed versus unconfirmed cardiac origin. In the unconfirmed angina analysis, the 75th percentile for weight contrasted with the 25th percentile was associated with a 50% increase in the risk of being labelled as having angina (adjusted odds ratio (OR) = 1.59, 95% confidence interval (CI): 1.11-2.28), while a similar contrast for Quetelet Index was also associated with a nearly 2-fold increase in the risk of being labelled as having angina (adjusted OR = 1.74, 95% CI: 1.18-2.57).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

The compression of morbidity hypothesis: promise and pitfalls of using record-linked data bases to assess secular trends in morbidity and mortality.

Individuals who are 65 years of age and older have exhibited unprecedented declines in mortality over the past few decades in the United States. Whether this increased survival has been accompanied by delays in the onset of disease or greater age-specific morbidity remains unanswered because of a paucity of reliable information on secular trends in age-specific disease incidence and survival. The Rochester Epidemiology Project (REP) is one of a few existing medical record linkage systems that offer promise of providing some of the necessary information. Several examples are presented that illustrate the potential of medical record-linked data bases for examining secular trends in the association between age at onset of disease and age at death.

Age Factors↗
PubMed1991

Exposure to an aeroallergen as a possible precipitating factor in respiratory arrest in young patients with asthma.

BACKGROUND: Exposure to airborne spores of the common mold Alternaria alternata has been implicated in asthma attacks. Such exposure is particularly frequent in the Midwest during the summer and fall months. To determine the role of A. alternata in triggering severe asthma attacks, we investigated the cases of 11 patients with asthma who had sudden respiratory arrest and determined the frequency of sensitivity to this allergen in these patients. METHODS: The 11 patients (age range, 11 to 25 years) with initial episodes of respiratory arrest, which was fatal in 2 patients, were identified in the course of their care in our pediatric and adult clinical allergy practice and by a retrospective review of all Mayo Clinic records of patients with severe asthma cared for between 1980 and 1989. Skin-test reactivity to A. alternata and levels of IgE antibody against this mold in the 11 patients were compared with those in 99 matched controls with asthma who had no history of respiratory arrest. RESULTS: All the patients came from the upper Midwest, and the episodes of respiratory arrest occurred in the summer or early fall. Ten of the 11 patients with asthma who had respiratory arrest (91 percent) had positive skin-puncture tests for sensitivity to alternaria, as compared with 31 percent of the controls (P less than 0.001), and the serum levels of IgE antibodies to alternaria were elevated in all 9 patients tested. Among the covariates we examined (age, sex, and distance from the Mayo Clinic), only age was a significant confounder. After adjustment for age, alternaria skin-test reactivity was found to be associated with an increase of approximately 200-fold in the risk of respiratory arrest (adjusted odds ratio, 189.5; 95 percent confidence interval, 6.5 to 5535.8). CONCLUSIONS: Exposure to the aeroallergen A. alternata is a risk factor for respiratory arrest in children and young adults with asthma.

Adolescent↗
PubMed1991

Benign positional vertigo: incidence and prognosis in a population-based study in Olmsted County, Minnesota.

A retrospective review of our population-based medical records linkage system for residents of Olmsted County, Minnesota, revealed 53 patients (34 women and 19 men; mean age, 51 years) with newly diagnosed benign positional vertigo in 1984. The age- and sex-adjusted incidence was 64 per 100,000 population per year (95% confidence interval, 46 to 81 per 100,000). The incidence of benign positional vertigo increased by 38% with each decade of life (95% confidence interval, 23 to 54%). One patient had an initial stroke during follow-up; thus, the relative risk for new stroke associated with benign positional vertigo was 1.62 (95% confidence interval, 0.04 to 8.98) in comparison with the expected occurrence based on incidence rates for an age- and sex-adjusted control population. The observed survival among the 53 Olmsted County residents with benign positional vertigo diagnosed in 1984 was not significantly different from that of an age- and sex-matched general population. Patients with benign positional vertigo seem to have a good prognosis.

Adolescent↗
PubMed1991

Functioning insulinoma--incidence, recurrence, and long-term survival of patients: a 60-year study.

For the 60-year period from 1927 through 1986, we assessed the incidence, recurrence, and long-term survival among all Mayo Clinic patients with histologically confirmed functioning insulinoma. With use of the complete medical record system at Mayo and the comprehensive epidemiologic data base of residents of Olmsted County, Minnesota, we found 224 patients in whom an initial pancreatic exploration at Mayo had confirmed the presence of insulinoma. The median age (and range) of these patients at surgical diagnosis was 47 (8 to 82) years, and 59% were female patients. During the study period, eight cases of insulinoma occurred among residents of Olmsted County; their age and gender distributions were similar to those of the total cohort. The incidence of insulinoma among residents of Olmsted County increased during the study period to a stable level during the last 2 decades of 4 cases per 1 million person-years. For the total cohort, 7.6% had multiple endocrine neoplasia type I (MEN I), and 5.8% had malignant insulinoma. The risk of recurrence was greater among patients with MEN I (21% at 10 and 20 years) than in those without MEN I (5% at 10 years and 7% at 20 years). Although survival of the total cohort was not significantly impaired, it was significantly worse than expected for patients with malignant insulinoma (29% versus 88% expected at 10 years postoperatively). We conclude that insulinoma is less rare than previously suspected. After successful surgical removal, the long-term risk of recurrent insulinoma is relatively high in patients with MEN I; for patients with benign disease, the long-term survival is normal.

Adolescent↗
PubMed1991

Evaluation and management of patients with both peripheral vascular and coronary artery disease.

The prevalence of serious angiographic coronary artery disease ranges from 37% to 78% in patients undergoing operation for peripheral vascular disease. Clinical studies have demonstrated that cardiac outcome after peripheral vascular surgery is not adequately predicted by the standard criteria of history, physical findings and rest electrocardiogram. An adequate exercise work load, left ventricular function and thallium redistribution have proved important in perioperative risk stratification. The choice of a perioperative functional cardiac test depends on patient-related factors and the nature of the peripheral vascular operation. Although procedures involving aortic cross-clamping exert a greater hemodynamic stress than do carotid endarterectomy and femoral popliteal surgery, late cardiac morbidity and mortality are significant in all patients with atherosclerotic disease. The decision to proceed with preoperative coronary angiography and myocardial revascularization should be based primarily on indications independent of the peripheral vascular procedure. However, peripheral vascular surgery may influence the timing of myocardial revascularization. Patients with high risk or unstable coronary artery disease may benefit from preoperative coronary revascularization, although this hypothesis remains unproved. In all patients, careful monitoring during and after operation is essential. All patients with peripheral vascular disease should be considered to be at lifelong risk for fatal and nonfatal cardiac events and should undergo appropriate clinical and laboratory evaluation and be treated accordingly.

Coronary Disease↗
PubMed1991

Late iliac artery aneurysms and occlusive disease after aortic tube grafts for abdominal aortic aneurysm repair. A 35-year experience.

Controversy continues over whether patients treated with straight Dacron aortic tube grafts for an abdominal aortic aneurysm remain at significant risk for subsequent development of iliac aneurysm or occlusive disease. To address this issue, the authors performed a population-based analysis of 432 patients who had an abdominal aortic aneurysm diagnosed between 1951 and 1984. Aneurysm repair was performed eventually in 206 patients (48%). To ascertain differences in late development of graft-related complications, iliac aneurysms, and arterial occlusions, the authors compared all tube-graft patients with similar numbers of bifurcated-graft patients matched for age and year of operation. In the tube-graft group, no subsequent clinically evident or autopsy-proven iliac aneurysms or iliac occlusive disease were noted. Over a mean follow-up of 6 years (range, 4 to 18 years), new aortic aneurysms occurred in the proximal aorta in both tube and bifurcated-graft patients (5.0% and 2.5%, respectively). In contrast the cumulative incidence of graft-related complications was higher with a bifurcated prosthesis (12.8%) compared with a straight graft (5.0%) (p = 0.15). These problems generally occurred 5 to 15 years postoperatively and emphasize the need for long-term graft surveillance. The authors conclude that straight tube-grafts for repair of abdominal aortic aneurysms provide excellent late patency with minimal risk of subsequent iliac aneurysm development.

Aged↗