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Biomedical subjects

D W Dippel

Publications and source records attributed to D W Dippel.

12 recordsLinked to original sources
PubMed1992

The nature of excess mortality in nursing home patients with dementia.

Survival and excess mortality in 606 dementia patients admitted to a psychogeriatric nursing home were analyzed in a historical prospective 8-year follow up. The overall 2-year survival rate after admission was 55%, 60% for women and 39% for men. Patients with senile dementia of the Alzheimer's type had higher 2-year survival rates than those with multi-infarct dementia (57% vs 41%). Physical impairment, inactivity, dependency as measured on an observational scale, and comorbidity had an adverse effect on survival. Diseases with the lowest two-year survival were myocardial infarction, heart failure, atrial fibrillation, parkinsonism, pulmonary infection, anemia, pressure sores, and malignancies. The mortality rates of dementia patients were higher than those of the general population, especially during the first months after admission. This excess mortality of dementia patients was better described by an additive than by a multiplicative factor, suggesting that dementia can primarily be regarded as an independent, competing mortality risk.

Aged↗
PubMed1992

Screening for unruptured familial intracranial aneurysms. A decision analysis.

Decision analysis is used to assess the decision to screen for unruptured intracranial aneurysms (IAs) in two affected families, and to formulate guide-lines for similar decisions. Four strategies are compared: "no screening", "screening directly", "screening twice", and "screening later". Intravenous and intra-arterial digital subtraction angiography techniques (iv-DSA, ia-DSA) are considered. Life years lived with and without disability are computed for each strategy. Loss of life expectancy with and without discounting and quality correction is used as an outcome measure. "No screening" is the preferred strategy when population based estimates of the prevalence of IAs are used. Thus, the results of this analysis provide no justification for screening patients without a familial history. But a physician who thinks that the risk of an IA is increased may rightly decide for screening, especially when the patient is aged 40 to 60. Ia-DSA is preferable over iv-DSA. A scenario analysis suggests that screening with magnetic resonance angiography is only slightly better than with ia-DSA, because the complication rate of screening plays a minor role in the analysis.

Adult↗
PubMed1992

Familial intracranial aneurysms. A review.

BACKGROUND: A familial occurrence of intracranial aneurysms is defined by the presence of such aneurysms in two or more first to third-degree family members. Families with two affected members may represent accidental aggregation. Other families show a frequency compatible with an autosomal dominant mode of inheritance. A genetic basis is also suggested by the younger average age of familial cases with a ruptured intracranial aneurysm (42.3 years versus an age range of 50-54 years for nonfamilial cases), occurrence at the same site or a mirror site in sibling pairs, occurrence in identical twins, and the association of intracranial aneurysms with genetically transmitted disorders. SUMMARY OF REVIEW: No reliable data are available about the occurrence of familial intracranial aneurysms among all patients with ruptured aneurysms; a frequency of 6.7% has been reported from a retrospective study, but a large part of the "familial" occurrence can be explained by fortuitous aggregation. The pathogenesis of familial intracranial aneurysms is not fully explained; a (partial) deficiency of type III collagen has been reported in sporadic, but not in familial, cases. Clinical decision analysis shows how the risk of harboring an intracranial aneurysm and the age of the patient are the main determinants for elective screening; lifetime risk of rupture (and therefore age) and surgical risks are the determinants for neurosurgical treatment. CONCLUSIONS: Surgical treatment is recommended for patients aged less than 70 years with a moderate or low surgical risk, and screening (preferably by intra-arterial digital subtraction angiography) is recommended only for relatives aged 35-65 years. Magnetic resonance angiography may develop into a useful alternative for screening, but the risks of diagnostic procedures play only a minor role in the decision analysis.

Decision Support Techniques↗
PubMed1992

Management of children with acute pharyngitis: a decision analysis.

BACKGROUND: Although the incidence of acute rheumatic fever has declined in the last decades, a few outbreaks have recently been reported. A rapid latex agglutination test for group A streptococci seems reasonably accurate, and early treatment of acute pharyngitis seems to influence the pharyngitis itself. These factors have promoted uncertainty concerning the current best management of patients with sore throat. METHODS: Clinical decision analysis is used to compare the risks and benefits of symptomatic treatment, and oral and intramuscular penicillin as therapeutic options, and the throat culture and the rapid latex agglutination test as diagnostic strategies. Best estimates of the risk of streptococcal pharyngitis, its complications, the carrier rate, the accuracy of diagnostic tests, the efficacy of antibiotic treatment, allergic reactions, medication compliance, and health outcomes are combined into a management advisory. All results are subjected to a sensitivity analysis in order to check their strength against plausible changes in assumptions. Quality adjusted life days (QALD) lost are used as an outcome measure. RESULTS: The agglutination test combined with oral penicillin yielded the lowest expected loss (.50) of QALD for a typical child with a risk of harboring streptococci of .60. The other strategies, however, yielded losses that were only several hundredths of QALD higher. CONCLUSIONS: For children with at least a 40% chance of harboring streptococci and a duration of complaints of less than 2 days before starting treatment, diagnostic testing and prescription of oral penicillin appear to be the best choice of initial management. The rapid latex agglutination test is more effective than the throat culture, because prompt penicillin treatment after a positive test result may shorten the duration of pharyngitis in infected children. High rates of acute rheumatic fever (over 5 X 10(-4] and low medication compliance change the best strategy to agglutination test with intramuscular administration of penicillin.

Acute Disease↗
PubMed1991

Survival of patients with dementia.

The evidence on survival in dementia is summarized. There are no reliable data on survival after onset of dementia or after first contact with medical services. People with dementia in outpatient clinics and nursing homes have 2-year survival rates of 75% (range 60%-95%) and 50% (range 30%-65%), respectively. Differences in survival between patients with senile dementia of the Alzheimer's type (SDAT) and multi infarct dementia (MID) are small. Women in nursing homes have a better prognosis than men (2-year survival rates, 60% vs 40%). Dementia patients have a considerable excess mortality when compared to the vital statistics. There is no evidence for improvement of survival rates during recent decades. Recommendations for future studies are made.

Alzheimer Disease↗
PubMed1990

Analysing clinical decision analyses.

We present a critical review of aspects of clinical decision analysis which uses an application to screening for familial intracranial aneurysms. The analysis is reported together with methods for assessing decision trees. These methods appear to be powerful checks on the usually rather intuitive way in which decision trees are built. The problem of assessing the uncertainty in the results of a decision analysis is discussed in detail. In practice, sensitivity analysis covers nearly every calculation apart from the standard evaluation of the decision tree. Different forms of sensitivity analysis are distinguished and given appropriate names: influence analysis, threshold analysis, full Bayesian analysis, Bayesian influence analysis, attribute analysis, generalization analysis and scenario analysis. The biostatistical community may well contribute to the much needed methodological improvement in decision analysis and its different forms of sensitivity analysis, especially if prepared to look beyond the standard statistical techniques.

Adult↗
PubMed1989

Decision analysis.

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Decision Making↗
PubMed1988

Treatment of intact familial intracranial aneurysms: a decision-analytical approach.

Clinical decision analysis is applied to the treatment decisions for four patients with unruptured familial aneurysms. The surgical treatment was uneventful in all patients except one with mild mixed aphasia and facial weakness postoperatively; these deficits disappeared in less than 2 years. In the decision analysis, discounted Quality Adjusted Life Years are used as an outcome measure. Probability estimates are extracted from the literature when available. It is concluded that the decision to treat the aneurysm neurosurgically in three of the four patients was correct. In two of these three patients, the decision cannot be altered by plausible changes in estimated data. For the third patient, only the combination of a low probability of rupture, a high surgical mortality and morbidity, and high discount favors conservative treatment. In the fourth patient, a toss-up situation exists. More knowledge of the probability of rupture, the probability of the development of other aneurysms, and the results of operation on intact intracranial aneurysms would have made the analysis more accurate. Clinical research should address these issues.

Adult↗
PubMed1986

A perspective on the role of decision analysis in clinical practice.

The upsurge in interest in clinical decision support techniques is not accidental. Clinical decision situations are more and more characterized by complexity and uncertainty, due to increasing diagnostic and therapeutic possibilities, the fast growth of medical knowledge, the increasing quality demands by the public, and the pressure towards cost-conscious decision making. On the other hand, information science is increasingly able to provide the tools for building decision-support systems. There are several approaches to the development of decision aids. The present paper is mainly concerned with one potentially very powerful method: decision analysis. Basically, decision analysis is a method for explicitating, structuring and analysing clinical decision situations for individual patients. Suggestions for therapy choice, and diagnostic and prognostic statements are obtained by integrating the probability and value judgments made during the analysis. A clinical decision analysis can conveniently be divided into four stages: defining and structuring the clinical problem, assessing the relevant probabilities and utilities, calculation of the preferred course of action, including sensitivity analysis, and formulation of the results of the analysis in a clinically useful way. An optimistic scenario of the future role of decision analysis in clinical medicine would describe--among others--decision-consultation departments, decision-oriented clinical data-bases and medical knowledge bases, research groups for development, testing, and updating of clinical strategies, decision-analysis courses in all levels of medical education, and decision-oriented clinical textbooks. Moreover, decision analysis will help in setting priorities in clinical research, in quality control and peer review, and in development of protocols for use by the paramedical personal. Some illustrations from applied decision analysis are given.

Decision Making, Computer-Assisted↗