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Biomedical subjects

H Brenner

Publications and source records attributed to H Brenner.

At least 145 records · Page 8Linked to original sources
PubMed1997

Disorders of the back and spine in construction workers. Prevalence and prognostic value for disability.

STUDY DESIGN: A cohort study on back-related morbidity and its impact on early retirement resulting from disability among employees in the construction industry. OBJECTIVE: To describe the prevalence of back-related morbidity according to different measures in various occupational groups and to assess the prognostic value of these measures for early retirement resulting from disability. METHODS: The results of occupational health examinations conducted in 1986-1988 among 4,958 employees of the German construction industry aged 40-64 years were analyzed. Active follow-up evaluation was carried out between October 1992 and July 1994 to ascertain employment status. RESULTS: Compared with that of white-collar employees, no excess risk for self-reported back pain or sciatica was seen for any of the manual professions. In contrast, the age-adjusted prevalence of clinical findings of the spine was elevated among all employees in manual professions, and the prevalence of a recorded diagnosis related to disorders of the back and spine (ICD-9 position 720-724) was elevated among bricklayers compared with white-collar employees. The relative risk of being granted a disability pension in the follow-up period was 1.6 (95% Confidence Interval [Cl], 1.3-2.1) for persons reporting back pain or sciatica, 1.8 (95% Cl, 1.4-2.2) for persons with an abnormal clinical finding of the spine, and 1.5 (95% Cl, 1.2-1.8) for persons with a recorded medical diagnosis related to disorders of the back or spine (ICD-9 720-724). CONCLUSION: Patterns of morbidity varied according to the evaluated morbidity measure. All three measures qualified as significant predictors of disability and helped to identify high-risk occupations and high-risk employees.

Back Pain↗
PubMed1997

Variation of sensitivity, specificity, likelihood ratios and predictive values with disease prevalence.

The sensitivity, specificity and likelihood ratios of binary diagnostic tests are often thought of as being independent of disease prevalence. Empirical studies, however, have frequently revealed substantial variation of these measures for the same diagnostic test in different populations. One reason for this discrepancy is related to the fact that only few diagnostic tests are inherently dichotomous. The majority of tests are based on categorization of individuals according to one or several underlying continuous traits. For these tests, the magnitude of diagnostic misclassification depends not only on the magnitude of the measurement or perception error of the underlying trait(s), but also on the distribution of the underlying trait(s) in the population relative to the diagnostic cutpoint. Since this distribution also determines prevalence of the disease in the population, diagnostic misclassification and disease prevalence are related for this type of test. We assess the variation of various measures of validity of diagnostic tests with disease prevalence for simple models of the distribution of the underlying trait(s) and the measurement or perception error. We illustrate that variation with disease prevalence is typically strong for sensitivity and specificity, and even more so for the likelihood ratios. Although positive and negative predictive values also strongly vary with disease prevalence, this variation is usually less pronounced than one would expect if sensitivity and specificity were independent of disease prevalence.

Data Interpretation, Statistical↗
PubMed1997

Reliability and validity of clinical outcome measurements of osteoarthritis of the hip and knee--a review of the literature.

High reliability and validity of clinical rating schemes is crucial for their use as outcome measurements of treatment of hip and knee osteoarthritis. In this paper, we review the empirical evidence on the reliability and validity of commonly used clinical scores. Clinical scores and related reliability and validity studies were identified by systematic literature search. Scores were classified according to the type and joint. Reliability and validity studies were characterized according to design, population, number and qualification of observers, number of measurements, time interval between repeat measurements and results. Reliability and validity studies were reported for only 6 and 15 of the 45 identified clinical scores, respectively. Although comparisons are difficult due to differences in study design, relatively high reliability was reported for most measurements of pain, stiffness, and physical function, while results are less conclusive for clinical signs. Most validity studies focused on the correlation between various scores. Correlation was generally found to be high for overall numerical ratings, but scores often differed with respect to the interpretation of these ratings. Validity has been more comprehensively studied for Lequesne's scores, WOMAC, and ILAS, and these scores have shown satisfactory responsiveness to different treatment effects. Overall, knowledge on reliability and validity of clinical scores of hip and knee osteoarthritis is limited, underlining the need for further properly designed and conducted studies.

Hip↗
PubMed1997

Body weight, pre-existing disease, and all-cause mortality in a cohort of male employees in the German construction industry.

The impact of body weight on all-cause mortality is subject to ongoing debate. We assessed the relation between body mass index (BMI) and all-cause mortality in a cohort of 8043 male employees in the German construction industry who underwent detailed occupational health examinations at ages 25-64 and who were followed for all cause mortality over an average period of 4.5 years. Overall, there was a negative, graded relation between BMI and all-cause mortality, which persisted after controlling for multiple covariates including age and cigarette smoking, and after excluding the initial two years of follow-up. There was a strong positive cross-sectional relationship between BMI and a medical diagnosis of diabetes, hypertension, and ischemic heart disease at the baseline examination. While BMI showed a strong negative relation with all-cause mortality among men with such diseases, the association was much weaker and non-monotonic for mean free of these diseases. Our results underline the importance of preexisting diseases for the prognostic value of body weight.

Adult↗
PubMed1997

Deriving more up-to-date estimates of long-term patient survival.

Statistics reflective of patient survival should be as up-to-date as possible. We illustrate that traditional methods for analysing survival have important limitations with regard to up-to-dateness of long-term cumulative survival estimates. We propose an alternative approach, denoted "period analysis," that may be used to overcome or at least substantially reduce these limitations. The conceptual background and the computational realization of the new method are outlined and its application is illustrated by an analysis of long-term survival of patients with testicular cancer in Saarland, Germany.

Cohort Studies↗
PubMed1997

Helicobacter pylori in out-patients of a general practitioner: prevalence and determinants of current infection.

Data on prevalence and determinants of Helicobacter pylori infection in well-defined populations are scarce. We investigated the prevalence and determinants of active H. pylori infection in a population of out-patients attending a general practitioner in Southern Germany. Infection status was determined by [13C]urea breath test. In addition, information on potential risk factors and medical history was collected. Five hundred and one of the 531 eligible patients participated in the study (response rate of 94.4%). In total, 117 of the 501 patients had a positive [13C]urea breath test (23.4%). Prevalence of H. pylori infection increased with age from 10.8% (95% CI 5.7-18.1%) in the age group 15-29 years to 30.8% (95% CI 22.1-40.6%) in the age group 60-79 years and was 20.3%, 30.4% and 28.2% for the age groups 30-39, 40-49 and 50-59 years, respectively. Education and childhood living conditions, especially the number of siblings, were identified as additional independent determinants of infection.

Adolescent↗
PubMed1997

Use of oral contraceptives and serum beta-carotene.

OBJECTIVE: Antioxidants, in particular carotenoids, may influence the risk for cardiovascular disease. This study investigates the influence of oral contraceptives (OC) on the serum concentration of beta-carotene, which may in turn affect the risk of cardiovascular diseases due to its antioxidative impact. DESIGN: Cross-sectional epidemiologic study. Examinations included a detailed questionnaire on medical history and lifestyle factors, a 7 day food record, and blood samples. SETTING: National health and nutrition survey among healthy people living in private homes in West Germany in 1987-1988. SUBJECTS: Nonpregnant and nonlactating women aged 18-44 (n = 610). RESULTS: Overall, the use of OC was negatively associated with serum beta-carotene concentration in bi- and multivariable analyses after adjustment for age, smoking, alcohol consumption, dietary intake of beta-carotene, use of vitamin supplements, body mass index, pregnancies, and serum concentrations of total triglyceride and cholesterol. A strong interaction between OC use and age on beta-carotene concentration was observed. While no relationship between OC use and serum beta-carotene was seen in the youngest age-group (18-24 y), there was a modest but significant negative association between OC use and beta-carotene levels among 25-34 y old women. The use of OC was associated with a strong decrease in beta-carotene levels among 35-44 y old women. The interaction between OC use and age could partly be explained by age dependent use of OC with higher estrogen content. CONCLUSIONS: OC use seems to be strongly related to serum beta-carotene levels, particularly among women above the age of 35. Further studies are needed to clarify the underlying mechanisms of this association and its implications for health risks of OC use.

Adolescent↗
PubMed1997

The association between alcohol consumption and all-cause mortality in a cohort of male employees in the German construction industry.

BACKGROUND: Many epidemiological studies have shown a J- or U-shaped association between alcohol consumption and total mortality. It has been argued that the higher mortality among abstainers than among moderate drinkers might result from misreporting of alcohol consumption, confounding or inclusion of a high proportion of ex-drinkers or individuals with pre-existing diseases among abstainers. METHODS: These concerns were addressed in a cohort study among 8043 construction workers aged 25-64 years who underwent occupational health examinations at six centres in South West Germany during 1986 to 1988. Abstainers were compared with alcohol users with respect to biological markers of alcohol consumption, prevalence of pre-existing diseases and other covariates. Study participants were followed for all-cause mortality until 1994. RESULTS: There was a clear monotonic dose-response relationship of biological markers with self-reported alcohol consumption. Prevalence of pre-existing diseases was highest among heavy drinkers, while no major differences were observed between abstainers and men who consumed 1-49 g of alcohol per day. Overall, 172 men died during the follow-up period. There was a strong U-shaped relationship between alcohol consumption and total mortality. Mortality was 2.8 times higher (95% confidence interval [CI]: 1.5-5.4) among non-drinkers than among men who consumed 1-49 g of alcohol per day after control for potential confounders in multivariable analyses. Strongly increased mortality was also found among heavy drinkers. Exclusion of non-drinkers with pre-existing diseases did not change the U-shaped association. CONCLUSIONS: We found a strong U-shaped association between alcohol consumption and all-cause mortality which is unlikely to be explained by misreporting, confounding or pre-existing disease.

Adult↗
PubMed1997

Chronic respiratory disease morbidity in construction workers: patterns and prognostic significance for permanent disability and overall mortality.

The aim of this study was to determine chronic respiratory disease morbidity in construction workers, and to assess the prognostic value of various morbidity measures on permanent disability and on all-cause mortality. Subjects in this analysis were male employees in the German construction industry, aged 40-64 yrs, who were examined by the occupational health service between August 1986 and December 1988. Prevalence of respiratory disorders as characterized by: 1) pathological findings on lung auscultation; 2) reduced forced expiratory volume in one second (FEV1); and 3) a medical diagnosis of chronic respiratory disease (International Classification of Diseases 9th revision (ICD-9) 490496) was assessed among occupational groups of construction workers, and compared with prevalence among white-collar employees. Active follow-up was conducted between October 1992 and July 1994 to ascertain working and life status (completeness: 92 and 96%, respectively). The prognostic value of the morbidity measures on permanent disability and on all-cause mortality was assessed using the Cox proportional hazards model. In the entire cohort, crude prevalence was 7.6% for pathological findings on lung auscultation, 8.8% for a reduced FEV1 (<70% of predicted value), and 6.1% for a recorded diagnosis of chronic respiratory disease. There was strong variation of prevalence with age, smoking status and, less clearly, occupation. The relative risk for permanent disability varied between 1.9 and 3.2, and for mortality between 2.0 and 2.9, respectively, when men with the various measures of bronchopulmonary disorders were compared with other men. The morbidity measures utilized allow the identification of employees at higher risk of disability and death, and this may facilitate targeting of specific prevention and rehabilitation measures.

Adult↗
PubMed1997

Use of commonly prescribed antibiotics is not associated with prevalence of Helicobacter pylori infection in adults.

BACKGROUND: The aim of the study was to investigate the association of the use of commonly prescribed antibiotics with prevalence of Helicobacter pylori infection in a population of adult outpatients. METHODS: All patients aged 15-79 years who visited the practice of a general practitioner (GP) between June and September 1996 in a suburban community near Ulm, a city in southern Germany, were asked to participate in the study. Infection status was determined with a 13C-urea breath test. In addition, the patients were asked to fill out a self-administered questionnaire. RESULTS: Overall, 475 outpatients were included in the study (response, 94.1%). A total of 266 patients (56.0%) reported a history of antibiotic treatment within the past 5 years, whereas 147 patients (30.9%) did not (62 patients (13.1%) did not know). Prevalence of infection in patients with a history of antibiotic medication during the past 5 years was 23.3%, whereas the prevalence of infection was 20.4% in subjects without antibiotic treatment (P = 0.283 after stratification for age). Control for other potential confounders by multivariable analysis did not materially alter the results. CONCLUSION: Coincidental antibiotic treatment is not associated with H. pylori prevalence in adults.

Adolescent↗
PubMed1997

Reliability of radiographic grading of osteoarthritis of the hip and knee.

We review studies on the reliability of radiographic assessment of osteoarthritis of the hip and knee. Reliability studies were reported for 10 among 24 identified scores. In general, moderate to good agreement was found for overall scores and for separate grading of joint space narrowing of the hip and osteophytes of the knee in the majority of studies, while reliability tended to be lower for other radiographic features. Overall scores of the knee were more reliable than overall scores of the hip, and intra-rater-reliability was considerably higher than inter-rater-reliability in most instances. Comparison of reliability between scores can only be made with caution, given the difference in the design of reliability studies, particularly the different qualification of involved observers. The limits of existing knowledge on reliability of commonly used radiologic scores are outlined, and, proposals are made to overcome those limits in future studies.

Adult↗
PubMed1997

Controlling for continuous confounders in epidemiologic research.

Multiple regression models are commonly used to control for confounding in epidemiologic research. Parametric regression models, such as multiple logistic regression, are powerful tools to control for multiple covariates provided that the covariate-risk associations are correctly specified. Residual confounding may result, however, from inappropriate specification of the confounder-risk association. In this paper, we illustrate the order of magnitude of residual confounding that may occur with traditional approaches to control for continuous confounders in multiple logistic regression, such as inclusion of a single linear term or categorization of the confounder, under a variety of assumptions on the confounder-risk association. We show that inclusion of the confounder as a single linear term often provides satisfactory control for confounding even in situations in which the model assumptions are clearly violated. In contrast, categorization of the confounder may often lead to serious residual confounding if the number of categories is small. Alternative strategies to control for confounding, such as polynomial regression or linear spline regression, are a useful supplement to the more traditional approaches.

Bias↗
PubMed1997

[Public health].

Explore the source record for details and available documents.

Forecasting↗
PubMed1997

[Reliability of expert assessment in disability evaluation within the scope of disability insurance].

With the introduction of the law on the statutory nursing care insurance in Germany ("Pflegeversicherung") in 1995, new benefits are provided for the most severely disabled people. Provision of benefits is contingent on a standardised examination performed by the medical service of the German statutory health insurance system (MDK). Results of the first study on the inter-rater reliability of this standardised examination are presented in this paper. The study population consisted of 218 elderly people (age range 60-99) living in 4 nursing homes in Munich. They were assessed by 2 senior medical students and 2 nurses using the standardised questionnaire of the MDK. Inter-rater reliability was assessed by means of kappa coefficients. Reliability was assessed with regard to the summary judgement of disability and the rating of single items (with regard to limitations in activities of daily living, mental status or the prognosis). Inter rater reliability was higher for the overall assessment of disability (kappa = 0.71 between medical students, kappa = 0.66 between nurses) than for most of the single items of the questionnaire such as "need of assistance with dressing" (kappa = 0.57 between medical students, kappa = 0.66 between nurses) or "ability to move" (kappa = 0.58 between medical students, kappa = 0.67 between nurses). Kappa-coefficients were particularly low for variables concerning prognosis of participants and for the mental status item "self-disorientation" (kappa = 0.19 between medical students, kappa = 0.23 between nurses). These patterns were consistently observed for the 2 rater groups (student-student, nurse-nurse). Between the 2 rater groups there was no substantial difference in reliability. However, there was a trend for higher agreement within the group of nurses. Although the overall reliability of the assessment of disability is relatively high in comparison to many other diagnostic procedures (such as x-ray readings), efforts should be made towards further improvement of this standardised examination.

Activities of Daily Living↗
PubMed1996

An alternative approach to monitoring cancer patient survival.

BACKGROUND: Monitoring patient survival, a practice routinely employed by many cancer registries, is an essential component of the evaluation of progress against cancer. However, changes in prognosis over time are disclosed with considerable delay, with traditional methods of monitoring cumulative survival. METHODS: This article introduces an alternative approach, denoted "period monitoring." which aims at more timely detection of such changes. The conceptual background and the computational realization of the proposed method are outlined, and its application is illustrated by an empirical example from the population-based cancer registry of Saarland, Germany. RESULTS: The principle of period monitoring is shown to be analogous to the well established use of period life tables in the field of demography. Computational realization of period monitoring can be achieved with simple modifications of standard survival analysis techniques. Compared with traditional methods of monitoring survival, period monitoring can advance detection of changes in cumulative survival considerably. CONCLUSION: Despite some limitations with respect to the ease of data interpretation. period monitoring offers a useful supplement to existing methods of monitoring patient survival.

Humans↗
PubMed1996

How independent are multiple 'independent' diagnostic classifications?

Multiple performances of diagnostic tests are commonly employed in clinical practice and epidemiologic research to assess test reliability, to increase sensitivity or specificity, or to correct for misclassification bias. An assumption almost universally made in this context is the assumption of independence of test results conditional on the true value. For dichotomous diagnostic tests, for example, disease present or absent, this assumption is usually not tenable, however, since there is typically a continuum of the traits that underly diagnosis and individuals in the vicinity of the (implicit or explicit) diagnostic cutpoint (such as the threshold of clinical detectibility) are more likely to be misclassified than other individuals. This paper assesses the magnitude of the resulting correlation of diagnostic errors as a function of the distribution of the underlying trait, the magnitude of the measurement error and the diagnostic threshold. It is concluded that errors of diagnostic tests can be strongly correlated even if errors in perception of the underlying trait are independent. It is illustrated by numerical examples that such positive correlation of diagnostic errors can substantially inflate commonly employed indices of reliability, such as the kappa coefficient.

Bias↗