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Bernt-Peter Robra

Publications and source records attributed to Bernt-Peter Robra.

5 recordsLinked to original sources
PubMed2006

A preference-based measure for test performance with an application to prenatal diagnostics.

Clinical epidemiology generally uses the receiver operating characteristic curve to summarize the accuracy of a diagnostic test and to compare the relative performance of different tests. This paper extends this concept to include the utility gains and losses of true and false test outcomes over the range of a priori risk. A utility index is developed first in situations where test accuracy is exogenously given, second where the test cutpoint can be chosen by the clinician according to the patient's a priori risk and preferences. By integrating over the a priori risk range, we derive an overall measure for a test's performance weighted by utility gains and losses. An example in prenatal diagnostics finally illustrates the clinical uses of the novel approach. Integrating patients' preference into clinical decision making will lead to different cutpoints and different assessments of test performance compared to unweighted policies.

Diagnostic Tests, Routine↗
PubMed2004

[Mammogram results in ambulatory care--a mammography quality circle in Braunschweig, Germany, between 1998 and 2001].

Radiologists from seven independent practices in Germany (average number of cases 3,500 in 2001) combined to form a mammography quality control group. Documentation and follow up were standardised for all cases that resulted in a referral for open biopsy. A quantitative analysis of the data would be expected to clarify the quality achieved in ambulatory care and to show further possibilities for quality assurance measures. The first overall analysis of 2,500 referrals for biopsy from 1998 to 2001 shows differences between practices as regards the frequency of referral for biopsy and the proportion of referrals for suspected malignancy, which are based on practice-specific conditions (referral behaviour, age structure of patients) and individual case management. Practices are very close in relation to positive predictive value (ppv) and detection rate. The biopsy rate in 2001 slightly exceeded 3%, the overall detection rate was 1.7%, and ppv 81%. For asymptomatic women detection rate and ppv were 0.5% and 70%, respectively. Quality parameters for all mammography referrals in total exceed those of screening programmes. When restricted to asymptomatic women, results have been achieved that are comparable to those of established screening programmes. Naturally the patients involved here are those in whom mammography was indicated. Nonetheless, these results demonstrate a high quality of detection on the part of those performing mammography in routine ambulatory care, and can be used as a reference for other types of care. With consistent quality assurance in relation to technical considerations and personnel, a performance quality can be achieved in independent practices which to date has not been surpassed by specialist mammography centres.

Adult↗
PubMed2002

Assessing the suitability of cross-sectional and longitudinal cardiac rhythm tests with regard to identifying effects of occupational chronic lead exposure.

The aim of this study was to examine whether signs of neurotoxic influence on the autonomic nervous system, after lengthy occupational lead exposure, could be revealed by appropriate cardiac rhythm analysis. A total of 109 male lead-exposed workers and 27 controls were examined in a cross-sectional study. In addition, 17 lead-exposed participants were investigated a second time in a follow-up study 4 years later. Heart rate variability was assessed in rest, strain, and recovery phases. In the cross-sectional study, lead-exposed persons showed a delayed restoration of cardiac rhythm parameters to the initial vegetative state after the strain phase. This effect significantly increased over a period of 4 more years of exposure in the 17 workers participating in the follow-up study. We found vagal depression caused by long-term lead exposure within the current threshold limit value range, which can be interpreted as an adverse effect.

Arrhythmia, Sinus↗
PubMedDate not supplied

A priori risk and optimal test accuracy in prenatal diagnostics.

The prevalence of fetal chromosome anomalies rises exponentially with the age of the pregnant woman. The risk of fetal anomalies can be specified using biochemical screening tests such as the triple test. This test substantially reduces the number of amniocenteses and proportionally the number of procedure-related miscarriages. However, disadvantages of the triple test include the utility loss of pregnant women who, following a false-negative test result, do not undergo amniocentesis and bear a disabled child as well as the intangible cost of a false-positive triple test. This paper employs a decision-analytic model to reveal the evaluation of this tradeoff, which is implicitly fixed by policy recommendations for a direct amniocentesis at maternal age of 35. It then determines the optimal level of cutoff risk for the triple test, and derives comparative static results: the optimal test accuracy decreases with increasing a-priori risk and increases with a rise in the miscarriage risk and in the woman's preference for detecting an affected fetus as compared to avoiding a miscarriage of an unaffected fetus. These results are in contrast to current clinical practice, where the cutoff of the triple test usually remains fixed.

Adult↗