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H Brenner

Publications and source records attributed to H Brenner.

At least 181 records · Page 10Linked to original sources
PubMed1995

Limitations of the death certificate only index as a measure of incompleteness of cancer registration.

The death certificate only (DCO) index, which quantifies the proportion of patients for whom the death certificate provides the only notification to the registry, is a widely used measure of incompleteness of population-based cancer registration. This paper provides an algebraic assessment and a quantitative illustration of the relationship between the DCO index and incompleteness of cancer registration. It is shown that the relationship between the DCO index and incompleteness of registration is strongly dependent on the case fatality rate and the misclassification rates of cancer deaths among unregistered patients. Therefore, the DCO index is a very poor indicator of incompleteness. Similar limitations apply to the DCN index (proportion of cases first notified by death certificate), which has been proposed as an alternative measure of incompleteness.

Death Certificates↗
PubMed1995

Use and limitations of the capture-recapture method in disease monitoring with two dependent sources.

Capture-recapture techniques are employed increasingly to correct for underascertainment of cases in epidemiologic surveillance. A key assumption of the basic two-source capture-recapture method is the independence of sources, which is often violated in practice. This paper provides a quantitative comparison of the performance of the capture-recapture method and the traditional registration approach in disease monitoring with two dependent sources. If sources are negatively dependent, underascertainment of cases by the traditional registration approach is transformed into overestimation of case numbers with the capture-recapture method. This overestimation can be extreme under certain conditions. Application of the capture-recapture method is therefore discouraged if negative source dependence is of concern. In other situations, the capture-recapture method can be a valuable tool to correct for underascertainment of cases. Although the correction remains imperfect if notifications from both sources are positively dependent, underestimation of case numbers is typically much less severe than with the traditional registration approach. I illustrate the findings for a broad range of registration scenarios and provide empirical examples from population-based cancer registration. I also discuss strategies that may minimize the degree of source dependence in the design and analysis of capture-recapture studies.

Cross-Sectional Studies↗
PubMed1995

Estimating completeness of cancer registration: an empirical evaluation of the two source capture-recapture approach in Germany.

STUDY OBJECTIVE: In recent years, capture-recapture methods have become increasingly popular in estimating completeness of disease registries. This study aimed to assess the performance of the two source capture-recapture method in estimating the completeness of cancer registration. DESIGN: The study was conducted in the population based cancer registry of Saarland, Germany, for which there are three main sources of notifications: reports by clinicians and pathologists, and death certificates. For groups of cases notified by one of the three sources, known completeness of registration by the other two sources was compared with the corresponding two source capture-recapture estimates. PATIENTS: A total of 16,020 patients notified to the cancer registry in 1970, 1975, 1980, and 1985 were included in the analysis. MAIN RESULTS: There was a tendency towards underestimation of completeness of notifications from pathologists and death certificates for patients notified by clinicians which was essentially confined to the older age groups. In contrast, capture-recapture methods tended to overestimate completeness of notifications from clinicians and death certificates for patients notified by pathologists. This overestimation was observed consistently in all age groups and for all of the most common cancer sites. Nevertheless, deviations of estimated completeness from known completeness were generally small or moderate. Agreement between estimated and known completeness was closest for patients notified by death certificates, although completeness was somewhat underestimated in patients above age 75. The observed patterns are in agreement with knowledge on clinical aspects and clinical management of cancer patients and with the circumstances of cancer registration in Saarland. CONCLUSIONS: Careful application of capture-recapture methods may provide an alternative to traditional approaches for estimating completeness of cancer registration.

Adolescent↗
PubMed1995

Intraperitoneal chemotherapy with cisplatin and etoposide in ovarian carcinoma patients who are clinically in complete remission.

We assessed the efficacy of short term intraperitoneal treatment with cisplatin (200 mg/m2) and etoposide (300 mg/m2) in 21 ovarian carcinoma patients who were in complete clinical remission after completion of postoperative cisplatin based chemotherapy. Second-look laparotomy was done in 17 patients prior to intraperitoneal chemotherapy and in 10, minimal residual disease was found. The mean follow-up was 24 (range 9-54) months. The projected overall survival 54 months after diagnosis was 60% and the median PFI 26 months. The median survival and PFI of patients with minimal residual disease at second-look laparotomy was only 27 and 18 months respectively. In all patients with relapse the recurrence was intraperitoneal. The combination intraperitoneal chemotherapy schedule used does not seem to be more effective for ovarian carcinoma patients who are clinically in complete remission than the intraperitoneal treatment with cisplatin alone reported in other series.

Adult↗
PubMed1995

[Interrater reliability of expert assessment by the health insurance medical service in determining eligibility for disability benefits].

In this paper, we present the first study on the inter-rater reliability of a standardised examination of functional disability, employed by the medical service of the German statutory health insurance system ("Medizinischer Dienst der Krankenversicherung", MDK). 215 elderly adults (mean age 84) living in 6 nursing homes in Munich were included in the study. They were assessed by three medical students and two nurses of the respective nursing homes using the standardised questionnaire of the MDK. Inter-rater reliability of both a summary judgement of disability and of single items, such as impairments in activities of daily living, was assessed by kappa-coefficients. Inter-rater reliability was higher for the overall assessment of disability (kappa = 0.82 between nurses, kappa = 0.57 between medical students) than for most single items. Reliability was particularly low for some items on mental status (such as "restlessness") or perceptions (particularly visual perception) which require clearer definition. This pattern was consistently observed for the two types of comparisons (inter-students, nurse-nurse) and for different subgroups of the study population.

Activities of Daily Living↗
PubMed1994

Smoking regulations at the workplace and smoking behavior: a study from southern Germany.

BACKGROUND: The relationship between smoking regulations at the workplace and smoking habits was assessed among public-sector employees in southern Germany. METHODS: A cross-sectional study was conducted among 931 employees who were working under three different, long-existing types of smoking regulations: (a) no restrictions at all, (b) a requirement that employees make their own agreement, and (c) a general prohibition of smoking. RESULTS: Smoking prevalence was lower among employees at workplaces with smoking restrictions (24.8 and 29.2% for workplaces with the agreement policy and the general smoking ban, respectively) than among other employees (31.4%), but these differences were not statistically significant. Large and highly statistically significant (P < 0.001) differences were found, however, in the average numbers of cigarettes smoked per day by active smokers. The mean number ranged from 20.5 in smokers without worksite restrictions to 14.1 and 13.2 in smokers working under the agreement policy and the general smoking ban, respectively. These differences persisted after multivariable control for potential confounders. CONCLUSION: Despite inherent limitations of the cross-sectional study design, our results suggest that regulation of smoking at the workplace may help active smokers substantially reduce their daily cigarette consumption. Such regulations might therefore be very effective public health measures.

Adult↗
PubMed1994

Chance-corrected measures of the validity of a binary diagnostic test.

Chance-corrected measures of the validity of diagnostic tests can be a valuable supplement to traditional measures which do not take chance-agreement between diagnostic test and true disease status into account. Recently, several authors have propagated chance-corrected measures of sensitivity and specificity, the most commonly employed indices of validity of binary diagnostic tests. A major limitation of these measures is their dependence on disease prevalence. In this paper, we propose simple alternative chance-corrected measures of sensitivity and specificity which do not share this limitation. The chance-corrected measure of sensitivity can be expressed as 1--negative likelihood ratio, and the chance-corrected measure of specificity can be expressed as 1--inverse of the positive likelihood ratio. The properties of the proposed measures are described and graphically illustrated, and formulas are given for point and interval estimation of the measures.

Models, Theoretical↗
PubMed1994

Estimating completeness of cancer registration in Saarland/Germany with capture-recapture methods.

Completeness of population-based cancer registration has been most commonly quantified by indirect measures, such as the death certificate only index or the mortality/incidence ratio. A major disadvantage of these measures is their strong dependence on the case fatality rate. Capture-recapture methodology offers an approach to estimate completeness directly which does not share this limitation. In this paper, a three-sources modelling approach is employed to derive estimates of completeness for the population-based cancer registry of Saarland. Overall, completeness is found to be high: estimates for all types of cancer range from 95.5 to 96.9% for calendar years 1970, 1975, 1980 and 1985. There is some variation with age (consistently high levels above age 30 years, a minimum of 87.7% in age group 15-29 years) and between cancer sites. Among the most common cancer sites, estimates of completeness are highest for gastrointestinal cancers (97.2%) and breast cancer (97.1%), while lower estimates of completeness are derived for cancers of the female genital organs (92.5%), the urinary tract (91.8%) and the prostate (91.0%). Although capture-recapture estimates are sensitive to the underlying assumptions about dependence between sources, careful application is encouraged to supplement traditional methods for evaluating completeness of cancer registration.

Adolescent↗
PubMed1994

General practice vocational training and public health medicine: a novel collaboration.

The incorporation of a module of public health teaching into a general practice vocational training programme is described. This programme is itself innovative in that in addition to the 2 years of hospital-based training, it provides 2 years of community-based training. While the curriculum of the public health module is evolving with time, the objectives have remained the same, and are being met. The module has been appraised by external observers, and has been evaluated by participating trainees. The public health module is now an established feature of the Sligo general practice training programme.

Community Medicine↗
PubMed1994

Application of capture-recapture methods for disease monitoring: potential effects of imperfect record linkage.

Capture-recapture methods are increasingly employed to correct for underascertainment of cases in disease monitoring. Routine systems of disease monitoring, such as morbidity registries, are often prone to specific threats of validity, such as in imperfect diagnoses or imperfect record linkage. A quantitative assessment is given of the performance of the two-source capture-recapture method for disease monitoring in the presence of imperfect record linkage. The capture-recapture approach can eliminate underestimation of the number of eligible cases, which is typical for most disease monitoring systems, under certain conditions, including independence of sources of case ascertainment and perfect record linkage. Correction for underestimation remains less than perfect, however, in the case of false-positive matches, whereas application of capture-recapture methods leads to overestimation of case numbers in the presence of false-negative matches. A simple correction procedure to overcome potential overestimation by false-negative matches is outlined.

Data Collection↗
PubMed1994

Intraperitoneal cisplatin chemotherapy versus abdominopelvic irradiation in ovarian carcinoma patients after second look laparotomy. A reassessment based on mature data.

In a previously published study we compared the outcome probability within 3 years after diagnosis in two groups of advanced ovarian carcinoma patients in complete clinical remission with minimal or no residual disease at second look laparotomy, performed after completion of cisplatin based combination chemotherapy. One group (n = 18) received after reexploration, abdominopelvic irradiation (RT group), the other diagnosed during a later period (n = 19), received after reexploration three courses of introperitoneal cisplatin chemotherapy with systemic thiosulfate protection (IP) group). In the present study the outcome of the same patients is compared after they have all been followed for at least 5 years or till death. A clear trend towards a more favorable, through statistically not significant, 5 year survival was observed (68%), in the IP group, vs 39% in the RT group (p = 0.07). In patients with a negative second-look laparotomy, the respective 5 year survival rates were 92% and 60% (p = 0.08). While the duration of the progression-free interval was similar in both treatment groups the survival after diagnosis of recurrence was significantly better in the IP group (41% vs 0%, p = 0.03).

Abdomen↗
PubMed1994

Varied forms of bias due to nondifferential error in measuring exposure.

Continuous exposure variables are frequently categorized in epidemiologic data analysis. It has recently been shown that such categorization may transform nondifferential error in measuring continuous exposure variables into differential exposure misclassification. This paper assesses the direction and magnitude of the resulting misclassification bias under a variety of practically relevant forms of nondifferential measurement error. The expected bias of measures of the exposure-disease association is toward the null in the case of purely random measurement error with a mean of zero. Systematic nondifferential over- or underestimation of the exposure may bias measures of the exposure-disease association either toward the null or away from the null, depending on the underlying distribution of exposure, the true exposure-disease relation, and the cutpoints employed for categorization. If exposure measurement error has both random and systematic components, the direction of the net bias is less predictable than with pure error of either type, but bias toward the null is increasingly likely as the random component grows larger. The results indicate the need for careful evaluation of potential effects of nondifferential exposure measurement error in epidemiologic studies in which categories are formed from continuous exposure variables.

Bias↗
PubMed1994

How to correct for chance agreement in the estimation of sensitivity and specificity of diagnostic tests.

The traditional concept of describing the validity of a diagnostic test neglects the presence of chance agreement between test result and true (disease) status. Sensitivity and specificity, as the fundamental measures of validity, can thus only be considered in conjunction with each other to provide an appropriate basis for the evaluation of the capacity of the test to discriminate truly diseased from truly undiseased subjects. In this paper, chance-corrected analogues of sensitivity and specificity are presented as supplemental measures of validity, which pay attention to the problem of chance agreement and offer the opportunity to be interpreted separately. While recent proposals of chance-correction techniques, suggested by several authors in this context, lead to measures which are dependent on disease prevalence, our method does not share this major disadvantage. We discuss the extension of the conventional ROC-curve approach to chance-corrected measures of sensitivity and specificity. Furthermore, point and asymptotic interval estimates of the parameters of interest are derived under different sampling frameworks for validation studies. The small sample behavior of the estimates is investigated in a simulation study, leading to a logarithmic modification of the interval estimate in order to hold the nominal confidence level for small samples.

Diagnostic Tests, Routine↗
PubMed1993

Clinical epidemiology of bilateral breast cancer.

BACKGROUND: The clinical epidemiology of bilateral breast cancer was assessed in a population-based study from Saarland, Germany. METHODS: Clinical aspects of breast cancer, including age and tumor spread at diagnosis and survival, were compared between 251 patients with bilateral breast cancer and all 9585 patients with a first diagnosis of breast cancer registered with the population-based cancer registry of Saarland, Germany, between 1968 to 1987. RESULTS: The patients with bilateral breast cancer were on average considerably younger at the time of diagnosis of the first breast cancer than the total group of patients with breast cancer (mean age, 55.7 years versus 60.5 years). Overall, the distribution of tumor spread at diagnosis of the second breast cancers was similar to the corresponding distribution of first breast cancers, but a much less favorable distribution was observed among second breast cancers that developed in women younger than 50 years of age. The survival rates after diagnosis of a second breast cancer were much worse than the survival rates after a first breast cancer diagnosis. These differences persisted after control for important covariates such as age and tumor spread and were more pronounced if the first tumor was diagnosed in an advanced stage and if the time interval between diagnosis of the first and second cancers was short. Nevertheless, tumor spread at diagnosis of the second cancer was by far the most important predictor of survival among patients with bilateral breast cancer. CONCLUSIONS: The differences in clinical aspects of first and second breast cancers should be considered in clinical management of patients with breast cancer. Further research is required to explain these differences.

Adult↗