Biomedical subjects

H Brenner

Publications and source records attributed to H Brenner.

At least 127 records · Page 7Linked to original sources

PubMed1998

An empirical investigation on matching in published case-control studies.

The methodological discussion about matching when recruiting controls in case-control studies has been controversial for a long time. To delineate the impact of this discussion on the practice of matching we reviewed 266 case-control studies published in nine yearly volumes of three major epidemiological journals within the period 1955-1994. Among studies published until 1980 71.7% of the control groups were recruited by individual matching compared to 46.4% in 1994. This decline is paralleled by an increase in the application of frequency matching (from 5.0% to 26.2%). As the issue of matching is closely connected with methodological questions of the statistical analysis we also examined the type of analysis applied to the data. We found that the use of logistic regression modeling has dramatically increased during this period (from 18.4% up to 87.2%), whereas application of the traditional Mantel-Haenszel technique for estimating summary odds ratios has nearly vanished. The correct approach for individually matched data in the logistic modeling framework, the conditional likelihood technique, has been unknown in the early part of the time window of our investigation, but is even nowadays applied by only three quarters of the corresponding studies. Our literature-based investigation provides thus compelling evidence that the type of control selection and statistical analysis used in case-control studies have changed substantially during recent years.

Case-Control Studies↗

PubMed1998

Recent improvement in survival of breast cancer patients in Saarland, Germany.

A new method for more timely monitoring of cancer patient survival was employed to assess progress in 5-year survival of breast cancer patients in Saarland, Germany, between 1980-84 and 1990-94. Five-year relative survival gradually increased from 68.8% to 73.5%. Improvements were most pronounced among age groups 50-59 and 60-69. The latter had the highest 5-year relative survival (77.1%) in 1990-94.

Adult↗

PubMed1998

Effect of oral contraceptive progestins on serum copper concentration.

OBJECTIVES: Recent epidemiologic studies have shown an increased mortality from cardiovascular diseases in people with higher serum copper levels. Even though higher serum copper concentration in women using oral contraceptives is well known, there is still uncertainty about the influence of newer progestin compounds in oral contraceptives on serum copper concentration. This issue is of particular interest in the light of recent findings of an increased risk of venous thromboembolism in users of oral contraceptives containing newer progestins like desogestrel compared to users of other oral contraceptives. DESIGN: Cross-sectional epidemiologic study. Examinations included a detailed questionnaire on medical history and lifestyle factors, a seven 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 y (n = 610). RESULTS: Overall, the use of oral contraceptives was positively associated with serum copper concentration in by bi- and multivariable linear regression models with log-transformed values of serum copper concentration as dependend variable and oral contraceptive preparations and potential confounding variables as independent variables. Serum copper concentration in women using oral contraceptives varied more strongly by different progestin compounds than by estrogen contents. The highest increase of serum copper was seen in women using oral contraceptives containing antiandrogen progestins (55%; 95% CI: 37-76%), followed by desogestrel (46%; 95% CI: 36-56%), norethisteron/lynestrenol (42%; 95% CI: 29-57%), and levonorgestrel (34%; 95% CI: 24-45%). CONCLUSION: While elevated serum copper concentration was found in users of all types of oral contraceptives, elevation was more pronounced among women taking oral contraceptives with antiandrogen effective progestins like antiandrogens or third generation oral contraceptives containing desogestrel. Further investigation is required to shed light on the possible role of high serum copper concentration in increasing cardiovascular or thrombotic risk of women using oral contraceptives.

Adolescent↗

PubMed1998

Variation in the 13C-urea breath test value by nationality in Helicobacter pylori-infected children.

BACKGROUND: The 13C-urea breath (13C-UBT) test value is (semi-)quantitatively related to Helicobacter pylori density in the gastric antrum, and the value correlates with the grade of gastritis. The aim of this study was to assess variation of the 13C-urea breath test value by sociodemographic factors in H. pylori-positive children. METHODS: The analysis was performed on 127 asymptomatic children (aged 5-7 years) who were identified as H. pylori-positive with the 13C-UBT test in a large population-based epidemiologic study in the city of Ulm (southern Germany). The parents of the children were asked to fill out a standardized questionnaire about sociodemographic data. RESULTS: Forty-two infected children (33.1%) were of German nationality, 47 children (37.0%) were of Turkish and 38 children (29.9%) were of another nationality. Turkish children had a significantly higher 13C-UBT value (geometric mean = 27.2%) than German children (16.7%) or children with another nationality (19.3%) (P < 0.001). Girls had a trend towards higher values than boys (P = 0.058 after adjustment for nationality). Body mass index, education of the parents, and prior use of antibiotics were unrelated to the extent of the 13C-UBT. CONCLUSIONS: This study identified significant variation in the extent of the 13C value by nationality among H. pylori-infected children. Further studies are needed to elucidate the causes and potential consequences of these variations.

Age Distribution↗

PubMed1998

The individual and joint contributions of Helicobacter pylori infection and family history to the risk for peptic ulcer disease.

Family history of peptic ulcer and infection with Helicobacter pylori have been identified as major risk factors for peptic ulcer disease. It is unclear, however, to what degree their impacts are independent of each other. This question was addressed in a cross-sectional study among 299 consecutive out-patients (25-54 years old) of a general practitioner. Adjusted odds ratios (95% confidence intervals) for gastroscopically verified peptic ulcer disease were 3.8 (1.4-10.1) for persons with H. pylori infection, 8.4 (2.9-24.1) for persons with a family history of ulcer, and 29.5 (6.1-143.9) for persons with both risk factors compared with persons without these risk factors. These results suggest strong, multiplicative contributions of both factors to the risk for peptic ulcer disease.

Adolescent↗

PubMed1998

Prevalence and determinants of Helicobacter pylori infection in preschool children: a population-based study from Germany.

BACKGROUND: Helicobacter pylori is among the most common infections in humans and has been recognized as major cause of various gastroduodenal diseases. There is limited knowledge, however, on the prevalence and determinants of this infection in children. We addressed these issues in a population-based cross-sectional study in Southern Germany. METHODS: Study subjects were all preschool children in Ulm, a city in the South of Germany, who were screened for school fitness by physicians of the public health service in 1996. Infection status was determined by 13C-urea breath test. In addition, the parents of the children were asked to fill out a standardized questionnaire. RESULTS: In total, 945 out of the 1201 eligible preschool children participated in the study (response rate = 79%). The children were aged 5-8 years. The majority were of German nationality (72.6%). Overall, 127 children (13.4%) were infected with H. pylori. Nationality, place of residence in the first year of life and duration of living in Germany were strongly associated with H. pylori infection status. The prevalence varied from 4.8% (95% confidence interval [CI]: 3.3-6.8%) in children with German nationality who were born in Germany or had lived in Germany since their first year of life to 66.7% (95% CI: 29.9-92.5%) in the children with Turkish nationality who came to Germany after the first year of life. CONCLUSION: Our results showed a large variation in prevalence of H. pylori infection in children living in the same geographical area according to nationality. They indicate an association between living conditions in early childhood and H. pylori infection and indicate that H. pylori associated morbidity may evolve very differently in population subgroups living in the same area.

Adult↗

PubMed1998

Pets are not a risk factor for Helicobacter pylori infection in young children: results of a population-based study in Southern Germany.

BACKGROUND: Helicobacter pylori may have multiple routes of transmission. It is unclear, however, whether the agent is also zoonotic and therefore transmitted from an animal reservoir. AIMS: The aim of this population-based study was to assess the relationship of exposure to pets and H. pylori infection among children in a population-based sample in Ulm, a city in the South of Germany. SUBJECTS AND METHODS: All children of German nationality who were to attend first grade in the school year 1996/1997 were included in the study. The 13C-urea breath test was used to determine active infection status. In addition the parents filled out a questionnaire to provide information about pets in the household as well as living conditions and socioeconomic factors of the family. RESULTS: Of 927 eligible preschool children 685 (74%) participated in the study. Prevalence of infection was 6.3%. Infection with H. pylori was not positively associated with contact with pets in general (p = 0.720) or to a specific kind of animal in bivariate and multivariable analyses as evaluated by means of logistic regression. CONCLUSIONS: These results suggest that pets in the household are not a risk factor for H. pylori infection among children in this population.

Animals↗

PubMed1998

Early retirement due to permanent disability in relation to smoking in workers of the construction industry.

Little is known about the relation of cigarette smoking and early retirement due to permanent disability. We conducted a cohort study among 4796 construction workers aged 40 to 59 who underwent occupational health examinations in 1986-1988 in occupational health centers located in the southern region of Germany. They were followed up with respect to working status until July 1994. The effect of smoking on early retirement due to permanent disability was assessed using the Cox proportional hazard model. Overall, smoking prevalence at baseline was 52%. The relative rate (RR) for permanent disability was 1.3 (95% CI 1.0-1.8) for all current smokers, compared with never-smokers. A positive dose-response relationship between smoking and the rate of early retirement due to permanent disability was found after adjustment for covariates. RR ranged from 1.3 in persons who reported smoking 1-19 cigarettes a day to 1.6 in persons who reported smoking > or = 30 cigarettes a day (P value for trend = 0.02). These findings underline the need for comprehensive efforts at the workplace to reduce smoking and its negative consequences for the individual, as well as to limit the associated social burden for society.

Adult↗

PubMed1998

Dyspepsia in relation to Helicobacter pylori infection and psychosocial work stress in white collar employees.

OBJECTIVE: We undertook an investigation of the relationship between psychosocial work stress and Helicobacter pylori (H. pylori) infection with dyspepsia. METHODS: We conducted a cross-sectional study among 189 employees of a health insurance company in the city of Ulm, Germany. RESULTS: A clear association between work-related psychosocial factors and the occurrence of dyspeptic symptoms during the past 3 months was evident. Persons who were considered to have a critical style of coping with work demands suffered more often from dyspeptic symptoms. Current infection with H. pylori was not associated with prevalence of dyspeptic symptoms. These results were also confirmed by adjustment for age, gender, smoking status, education, and use of antiinflammatory drugs within the past 3 months, by means of multivariate analysis. The odds ratio (OR) for having a dyspepsia symptom score in the upper tertile versus the 1st or 2nd was 3.22 (95% confidence interval [CI], 1.56-6.65), given that the employee was considered to have a critical style of coping with work demands. The OR for having a dyspepsia symptom score in the upper tertile given H. pylori infection was 1.23 (95% CI, 0.44-3.46), indicating no association of current H. pylori infection with dyspeptic symptoms. CONCLUSIONS: A critical style of coping with work demands may be an important determinant for dyspepsia-like symptoms. Therefore, in the absence of an underlying disease, specific intervention programs should be targeted at the behavior of the affected individual (e.g., stress-reduction programs) rather than on the treatment of specific symptoms or infection with H. pylori.

Adaptation, Psychological↗

PubMed1998

Prevalence of generalised osteoarthritis in patients with advanced hip and knee osteoarthritis: the Ulm Osteoarthritis Study.

OBJECTIVES: Different prevalences of generalised osteoarthritis (GOA) in patients with knee and hip OA have been reported. The aim of this investigation was to evaluate radiographic and clinical patterns of disease in a hospital based population of patient subgroups with advanced hip and knee OA and to compare the prevalence of GOA in patients with hip or knee OA, taking potential confounding factors into account. METHODS: 420 patients with hip OA and 389 patients with knee OA scheduled for unilateral total joint replacement in four hospitals underwent radiographic analysis of ipsilateral and contralateral hip or knee joint and both hands in addition to a standardised interview and clinical examination. According to the severity of radiographic changes in the contralateral joints (using Kellgren-Lawrence > or = grade 2 as case definition) participants were classified as having either unilateral or bilateral OA. If radiographic changes of two joint groups of the hands (first carpometacarpal joint and proximal/distal interphalangeal joints defined as two separate joint groups) were present, patients were categorised as having GOA. RESULTS: Patients with hip OA were younger (mean age 60.4 years) and less likely to be female (52.4%) than patients with knee OA (66.3 years and 72.5% respectively). Intensity of pain and functional impairment at hospital admission was similar in both groups, while patients with knee OA had a longer symptom duration (median 10 years) compared with patients with hip OA (5 years). In 41.7% of patients with hip OA and 33.4% of patients with knee OA an underlying pathological condition could be observed in the replaced joint, which allowed a classification as secondary OA. Some 82.1% of patients with hip and 87.4% of patients with knee OA had radiographic changes in their contralateral joints (bilateral disease). The prevalence of GOA increased with age and was higher in female patients. GOA was observed more often in patients with knee OA than in patients with hip OA (34.9% versus 19.3%; OR = 2.24; 95% CI: 1.56, 3.21). Adjustment for the different age and sex distribution in both patient groups, however, takes away most of the difference (OR = 1.32; 95% CI: 0.89, 1.96). CONCLUSION: The crude results confirm previous reports as well as the clinical impression of GOA being more prevalent in patients with advanced knee OA than in patients with advanced hip OA. However, these different patterns might be attributed to a large part to a different distribution of age and sex in these hospital based populations.

Age Factors↗

PubMed1998

Helicobacter pylori and abdominal symptoms: a population-based study among preschool children in southern Germany.

OBJECTIVE: To determine the relation of Helicobacter pylori infection with gastrointestinal symptoms in a healthy population-based sample of children. DESIGN: Population-based cross-sectional study of preschool children. SETTING: Screening examination for school fitness by physicians of the Public Health Service in Ulm, a city with 100 000 inhabitants in southern Germany. PARTICIPANTS: One thousand two hundred one preschool children. MAIN OUTCOME MEASURES: Infection status was determined by 13C-urea breath test. Information on gastrointestinal symptoms was collected from children's parents by a standardized questionnaire and integrated into a symptom score. Results. Nine hundred forty-five children participated in the study (response rate, 79%). Overall, 127 children (13.4%) were infected. H pylori infection was not positively related to specific gastrointestinal symptomatology. Infected children had even fewer symptoms when compared with uninfected children. CONCLUSIONS: Our results indicate that H pylori infection in children is mostly asymptomatic and not associated with specific gastrointestinal symptoms.

Abdominal Pain↗

PubMed1998

A potential pitfall in control of covariates in epidemiologic studies.

Control of covariates is essential in nonexperimental epidemiologic studies. Important covariates, such as smoking or alcohol consumption, often are crudely categorized in epidemiologic analyses. In this paper, I illustrate by both hypothetical and empirical examples that control of crudely categorized covariates can yield strongly misleading results. In particular, I show that, under certain conditions, control for crudely classified covariates can even be worse than not controlling for such covariates at all. I conclude that covariate specification is an issue that requires much more care than it commonly receives in epidemiologic analyses.

Case-Control Studies↗

PubMed1998

Effects of record linkage errors on disease registration.

Reliable record linkage is a prerequisite for high-quality population-based disease registration. Rapid developments in computer processing have made record linkage both more efficient and more reliable in recent years. At the same time, concerns about confidentiality increasingly hinder record linkage in many disease registries. This paper provides basic algebraic models describing the effects of record linkage errors on monitoring disease incidence. Homonym errors, that is, erroneous linkage of records that pertain to distinct individuals, lead to underestimation of incidence in the registry population. The degree of underestimation strongly depends on the discriminating power of personal identifiers and the record linkage procedure on the one hand, and the number of registered cases on the other hand. Synonym errors, that is, failure to link notifications on the same individual, lead to overestimation of incidence in the population base. The combined effects of record linkage errors are illustrated with empirical examples. We conclude that it is the largest and most informative disease registries that are potentially affected most by impediments of record linkage procedures due to unduly restrictive confidentiality rules.

Disease Notification↗

PubMed1998

Parental smoking and infection with Helicobacter pylori among preschool children in southern Germany.

Exposure to parental smoking is known to increase children's susceptibility to a variety of infections. We investigated the relation of parental smoking to infection with Helicobacter pylori in a population-based study among preschool children who were screened for school fitness in the city of Ulm, Germany, in 1996. Current infection with H. pylori was measured by a 13C-labeled urea breath test. Information on factors potentially related to H. pylori infection, including parental smoking in the household, was obtained from children's parents through a self-administered standardized questionnaire. Among 1,201 eligible children, 945 participated in the study (response rate = 79%). Overall prevalence of active infection was 13.7%. After adjustment for confounding factors, we found a strong positive relation between smoking by the father in the household and H. pylori infection (odds ratio = 3.7; 95% confidence interval = 2.3-6.1). By contrast, there was a strong negative relation between smoking by the mother and H. pylori infection (odds ratio = 0.4; 95% confidence interval = 0.2-0.8) that was most pronounced among children who had been breastfed. These striking patterns cannot be explained by current knowledge.

Child↗

PubMed1998

Serum cholesterol and osteoarthritis. The baseline examination of the Ulm Osteoarthritis Study.

OBJECTIVE: To assess the association between serum cholesterol and osteoarthritis (OA). METHODS: OA patterns were studied in 809 patients with knee or hip joint replacement due to OA in 4 hospitals in southwest Germany. Participants had a standardized interview and examination. Radiographs of the contralateral joint as well as both hands and a blood sample were obtained. Serum cholesterol levels were divided into tertiles and hypercholesterolemia was defined as > or = 6.2 mmol/l or use of antihyperlipidemic drugs. According to the presence or absence of radiographic OA in the contralateral joint, participants were categorized as having bilateral or unilateral OA. If radiographic OA of different finger joints was present, participants were categorized as having generalized OA. Odds ratios and 95% confidence intervals for the association of serum cholesterol with OA patterns were calculated with logistic regression, adjusting for potential confounders. RESULTS: Eighty-five percent of participants with radiographs had bilateral OA and 26% generalized OA. No association was observed between hypercholesterolemia and bilateral OA. Hypercholesterolemia (OR 1.61; 95% CI 1.06-2.47) and high serum cholesterol levels (3rd versus 1st tertile: OR 1.73; 95% CI 1.02-2.92) were independently associated with generalized OA. This association was almost exclusively due to participants with knee OA. CONCLUSION: These data add to the evidence regarding the independent role of serum cholesterol as a systemic risk factor for OA. The discrepant associations observed for different OA patterns are likely due to the relative weight of other risk factors.

Aged↗

PubMed1998

[Possibilities of epidemiologic studies within the scope of school entrance examinations exemplified by Ulm Helicobacter pylori studies].

This paper illustrates the possibilities and the evidential value of epidemiologic studies in combination with the pre-school screening examinations, which in Germany are mandatory for all children who are to attend school for the first time. Aspects of study design and study conduct are discussed primarily. We used two studies conducted in the city of Ulm in 1996 and in 1997. The aim of these studies was to investigate the prevalence, determinants and effects of Helicobacter pylori infection among pre-school children and their parents. Study subjects were all pre-school children in Ulm, a city in the South of Germany, who were screened for school fitness by physicians of the Public Health Service in 1996 and 1997, respectively. Infection status was determined by 13C-urea breath test. In addition, the parents of the children were asked to fill out a standardized questionnaire. In the 1997 study, the infection status of the accompanying parents was also evaluated by 13C-urea breath test. We present some selected results from the study of 1996. In total 945 out of the 1201 eligible pre-school children participated in the study (response rate = 79%). Overall, 127 children (13.4%) were infected with Helicobacter pylori. The prevalence varied between 6.1% in the children with German nationality to 44.8% in children with Turkish nationality and 24.8% in children with other nationality. In addition, we identified further determinants and investigated effects of the infection. The results of these studies demonstrate that epidemiologic studies combined with the mandatory screening examinations in pre-school children may be an important and feasible way to gain knowledge. The participation of the Public Health Service is of special advantage and allows to collect health related data in a efficient way.

Adult↗

PubMed1997

Effects of record linkage errors on registry-based follow-up studies.

The importance of reliable record linkage for high quality-population-based disease registration is widely recognized. Systematic methodologic work is lacking, however, on the effects of record linkage errors on the use of disease registries for epidemiologic purposes. The present paper provides algebraic models describing the effects of record linkage errors on monitoring survival of registered patients, which is commonly performed by matching registry records against a database of death certificates, and on registry-based incidence follow-up of external cohorts. Homonym errors, that is, erroneous linkage of records that pertain to distinct individuals, lead to underestimation of survival of registered patients and to overestimation of disease incidence among external cohorts linked to the registry, while synonym errors, that is, failure to link notifications on the same individual, have opposite effects. The magnitude of effects of record linkage errors are illustrated with numerical examples.

Bias↗

PubMed1997

Relation of smoking and alcohol and coffee consumption to active Helicobacter pylori infection: cross sectional study.

OBJECTIVE: To assess the relation of smoking and alcohol and coffee consumption to active Helicobacter pylori infection. DESIGN: Cross sectional study of patients attending a general practitioner. Active H pylori infection was measured by the 15C-urea breath test and detailed quantitative information on smoking and on alcohol and coffee consumption was obtained by a standardised self administered questionnaire. SETTING: One general practice in Germany. SUBJECTS: 447 patients aged 15-79 who had not had peptic ulcer disease or treatment for H pylori infection. MAIN OUTCOME MEASURES: Prevalence of H pylori infection according to smoking and alcohol and coffee consumption. RESULTS: Overall prevalence of infection was 21% (94/447). There was no significant relation between smoking and active H pylori infection. Alcohol consumption showed a negative dose-response relation and coffee consumption a positive dose-response relation with active infection. After adjustment for potential confounders, the odds ratios for patients who drank < or = 75 g and > 75 g of ethanol a week compared with non-drinkers were 0.90 (95% confidence interval 0.55 to 1.59) and 0.33 (0.16 to 0.68), respectively (P value for trend 0.005, assuming that 1 litre of beer and 0.51 of wine contain on average 50 g of ethanol in south Germany). Adjusted odds ratios for patients who drank < 3 cups and > or = 3 cups of coffee per day compared with those who did not drink coffee were 1.49 (0.71 to 3.12) and 2.49 (1.23 to 5.03), respectively (P value for trend 0.007). CONCLUSION: These results suggest a protective effect of alcohol consumption against active infection with H pylori and an opposite effect of coffee consumption.

Adolescent↗