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Biomedical subjects

A L Verbeek

Publications and source records attributed to A L Verbeek.

At least 91 records · Page 5Linked to original sources
PubMed1996

Prognosis of younger and older patients with early breast cancer.

The use of mammography in recent years has resulted in an increase in the detection of small breast cancers. The beneficial effects of early detection on breast cancer mortality seem to differ with age. To obtain more insight into this matter we studied the long-term prognosis of patients with early invasive breast cancers (T1) in three age groups: 144 patients of age 40-49, 402 patients of age 50-69 and 192 patients 70 years or older at diagnosis. In all age groups, patients with a tumour of 1 cm or less have a longer breast cancer specific survival than patients with a tumour larger than 2 cm. The survival advantage in the case of tumours of a size rounded to 1.5 cm compared with tumours larger than 2 cm in the under age 50 group was marginal (and not significant). However, older patients with tumours of this size do have a significantly improved survival. It is more difficult to improve survival in younger patients through early detection, partly because of an apparent early metastatic potential of their tumours. A reduction in breast cancer mortality might be expected in women younger than 50 years of age only if a substantial proportion of the invasive cancers are detected before their size exceeds 1 cm.

Adult↗
PubMed1996

Review article: symptom improvement through eradication of Helicobacter pylori in patients with non-ulcer dyspepsia.

The aim of this article is to determine, by reviewing the literature, whether treatment of Helicobacter pylori infection in patients with non-ulcer dyspepsia affects symptoms. Ten publications were identified through a computerized and manual literature search, and the percentage of patients with symptom improvement after successful or unsuccessful eradication therapy for H. pylori infection was calculated. In the 10 studies, symptom improvement after treatment was found in 73% of the patients that became H. pylori-negative and 45% of the patients that remained H. pylori-positive. Symptom improvement was modified by various clinical features and methodological aspects. If eradication of H. pylori failed, symptoms only improved over a short period. Symptom improvement was more pronounced in dyspeptic patients in whom H. pylori was eradicated than in those in whom H. pylori infection persisted.

Dyspepsia↗
PubMed1996

Prognostic models for the probability of achieving an ongoing pregnancy after in-vitro fertilization and the importance of testing their predictive value.

The aim of this study was to create reliable models to predict the probability of achieving an ongoing pregnancy during in-vitro fertilization (IVF) treatment: model A, at the start of the first treatment, model B at the time of embryo transfer, and model C, during the second treatment at the end of the first IVF treatment. Prognostic models were created using data from the University Hospital Nijmegen (n = 757) and applied to the data from the Catharina Hospital Eindhoven (n = 432), The Netherlands, to test their predictive performance. The predictions of model B (made at time of embryo transfer) were fairly good (c = 0.672 in the test population). For instance, 93% of the patients who had a predicted probability of achieving an ongoing pregnancy of < 10% did not achieve an ongoing pregnancy. However, the predictions of the other two models (A and C) for Eindhoven were less reliable. The predictive value of model C was fairly high in Nijmegen (c = 0.673). Its poor performance in the test population may be explained partly by differences in effectiveness of the ovulation stimulation protocols and the decision about when to discontinue the cycle. Thus, before using prognostic models at an IVF centre, their reliability at that specific centre should be tested.

Evaluation Studies as Topic↗
PubMed1996

Long term breast cancer screening in Nijmegen, The Netherlands: the nine rounds from 1975-92.

STUDY OBJECTIVE: To assess the performance of breast cancer screening in different age categories over two decades. DESIGN: Important determinants of reduced breast cancer mortality such as attendance, mammography performance, cancer detection, and disease stage were recorded. SETTING: Nijmegen, The Netherlands, 1975-92. SUBJECTS: Since 1975 more than 40,000 women aged 35 years and older have been invited biennially for breast screening in a population based project in Nijmegen. MAIN RESULTS: Rates of attendance, referral, detection, and disease stage were calculated, as well as the specificity of screening mammography and the predictive value of referral and biopsy. From round 3 onwards, the attendance rate of women younger than 50 years stabilised at 70%, in women of 50-69 years it was 62%, and in women aged 70 and over it was 22%. In these three age categories, the referral rates of a positive screening mammography per 1000 screened women were 4.9, 6.2, and 11.8, respectively. Specificity rates were between 99% and 100%. Current predictive values of referral were high: in the specific age categories 39%, 59%, and 68% of the referred women had cancer. Detection rates remained fairly stable over the rounds 4-9, at 1.9, 3.6, and 8.0 cancers per 1000 screened women. In the two year period between screening the numbers of interval cancers per 1000 screened women were 2.2, 2.2, and 2.9, for the three age categories respectively. With regard to invasive cancers detected during screening, the percentage of small tumours (< or = 20 mm on the mammogram) was 84% in each age category. For women younger than 50 years, the proportion of intraductal carcinoma in all the cancers detected at screening was 40%, while it was 15% in the other age categories. CONCLUSION: Throughout the nine rounds, the screening outcomes were found to be adequate, particularly considering the high specificity rate and the predictive value of referral without the interference of a low detection rate. Although the occurrence of interval cancers seemed high, it was similar to other screening programmes. Despite a relatively low referral rate, the ratios of screen detected versus interval cancer cases were favourable. Well organised screening programmes can achieve good mammography results without too many false positives. It is important that women continue to participate in a screening programme because cancer can still be detected even after several successive negative screening examinations.

Adult↗
PubMed1996

Maternal occupational exposure during pregnancy and the risk of spina bifida.

OBJECTIVES: A case-control study was carried out to explore associations between spina bifida and occupational exposure of the mother. METHODS: The cases were children with spina bifida aperta born between 1980 and 1992 from nine hospitals in the Netherlands. The controls were children born healthy in the same period as the cases, from hospitals and from the general population. Data collection was carried out in two steps. Firstly, postal questionnaires were sent to all the parents of cases and controls to gather information on occupations and potential confounders. In the second phase of the study, information on specific exposures was collected by means of job and task specific personal interviews. Interviews were performed with 55 case mothers and 66 control mothers who had occupations with a potential for chemical or physical exposure. Those exposures were assumed to be negligible for--for example, teachers and secretaries, so personal interviews were not indicated for these women. Information was collected on specific tasks in the period just after conception, and on the associated use of chemical or physical agents, frequency of exposure, and use of protective equipment. RESULTS: The analyses of occupation showed an increased risk for women working in agricultural occupations (OR = 3.4, CI:1.3-9.0), and, although less distinct, for cleaning women (OR = 1.7, CI:0.9-3.4). Only a few women seemed to be occupationally exposed to chemical or physical agents. No differences in occurrence of specific exposures could be detected between cases and controls. Besides, no differences were seen in pesticide or disinfectant exposure among case and control mothers in agricultural occupations. CONCLUSIONS: Occupational exposures of the mother during pregnancy were infrequent and did not seem to play an important part in the aetiology of spina bifida in this study. The association found between spina bifida and maternal agricultural occupations could not be explained by the use of pesticides by the mother or by any other occupational exposure.

Agriculture↗
PubMed1996

A criterion for stability of the motor function of the lower extremity in stroke patients using the Fugl-Meyer Assessment Scale.

A test-retest reproducibility study was performed to define a criterion for stability as opposed to change of motor function of the lower extremity in stroke patients. Forty-nine patients with stroke were examined twice by the same physiotherapist, using the Fugl-Meyer Assessment Scale. The interval between both measurements was three weeks. The mean differences between the first and the second measurement were small, with 0.04 points for the lower extremity scale and 0.92 points for the balance scale, respectively. Intraclass correlation coefficient for the lower extremity scale was 0.86, and 0.34 for the balance scale. The standard error of measurement for each scale was 1.76 and 1.17 points, respectively. The standard error of measurement can be transformed in an 'error threshold', which is a criterion to differentiate real changes from changes due to chance variation or measurement error. As the absence of real change is a parameter for stability, a change of less than 5 points for the lower extremity scale and of less than 4 points for balance confirms stability of motor function.

Adolescent↗
PubMed1996

Subclinical beriberi polyneuropathy in the low income group: an investigation with special tools on possible patients with suspected complaints.

OBJECTIVE: To determine the prevalence rate of subclinical beriberi polyneuropathy (PNP) in the low income group and to present new methods for early detection. DESIGN: We conducted a prospective, randomized observational study on all patients from family members of non-PNP patients presenting to the outpatient neurologic clinic of the Dr Soetomo Hospital in 1989 in Surabaya, Indonesia. MATERIAL AND METHODS: The 53 group I patients belonged to the low income series, whereas the 56 group II patients were from the mid- and high-income groups. We analyzed their diets and determined their blood thiamine levels. Neurologic, internal, psychiatric as well as neurophysiologic examinations were performed on all patients. RESULTS: The prevalence rate of subclinical beriberi PNP of the apparently healthy subjects of the low income group was 66% compared with 12.5% among the mid and high income groups. The exposure odds ratio was 13.6 (95% Cl, 2.78 to 8.04) indicating that the low income group ran a greater risk of developing beriberi PNP than the mid and high income groups. CONCLUSION: Most of our low income group patients had an inadequate diet, especially concerning deficient thiamine intake. Analysis of the diets revealed, that they were usually rich in carbohydrate especially steamed milled rice, whereas intake of fat and thiamine was low, protein was just sufficient. The calorie intake was marginal. Carbohydrate rich and non fat calories in the diet with low thiamine intake may provoke beriberi.

Adolescent↗
PubMed1995

[Mortality rate in lung cancer decreasing in men and increasing in women].

OBJECTIVE: To determine the trend in lung cancer mortality rates among men and women in the Netherlands during the period 1951 to 1992. DESIGN: Descriptive research. METHOD: In a previous paper the lung cancer mortality rates of men and women during the period 1951 to 1982 were analysed using the Netherlands Central Bureau of Statistics (CBS) population data and the CBS mortality data. The mortality rates were directly standardized for age using as a standard the Dutch sum population of 1951 to 1982. The current study describes the lung cancer mortality for men and women until 1992 using exactly the same methods. RESULTS: The direct standardized mortality rates for men had decreased since 1987. For women, on the contrary, these rates had increased further. The age-specific mortality rates for men have decreased since the calendar period 1983-1987 and since the birth cohort 1916-1920. The age-specific mortality rates for women have increased until the latest calendar period 1988-1992 and until the latest birth cohort 1931-1935. CONCLUSIONS: Lung cancer mortality in men has peaked, in women it is still rising.

Adult↗
PubMed1995

Nation-wide breast cancer screening in The Netherlands: support for breast-cancer mortality reduction. National Evaluation Team for Breast Cancer Screening (NETB).

The nation-wide 2-yearly breast-cancer screening programme in The Netherlands, for women aged 50-69, started around 1988, and was predicted to result eventually in a 16% reduction in breast-cancer mortality in the total female population. We present the results of screening up to January 1, 1993, and compare these with the predicted results from the cost-effectiveness analysis, on which basis this mortality reduction has been calculated. At least 550,000 women aged 50-69 were invited to screening in 1990-1992, and 75% of these participated. Cancer was suspected from 5,162 examinations and further investigation was therefore required. Excision biopsy was done in 72% of referrals, and 2,515 breast cancers were detected. The results for 404,000 newly invited women compare favourably with expected values (in parentheses): 78% attendance rate (70%), 1.4% screen positive (1.6%), 6.8 cancers detected per 1,000 women screened (6.4) and 38% of these cancers were DCIS or invasive carcinomas smaller than 11 mm in diameter (36%). More data, e.g., on treatment and interval cancers, will follow in the years to come. These first results can be interpreted as strong early signs of a reduction in breast-cancer mortality of at least the predicted size. Screening has sufficiently advanced the diagnosis, as well as or better than expected. Breast cancers diagnosed in this age group without screening are diagnosed at a worse stage than expected. Unfavourable side-effects, especially false-positive referrals, might be kept lower than those reported in other countries.

Aged↗
PubMed1995

Effect on breast cancer mortality of biennial mammographic screening of women under age 50.

The effects on breast cancer mortality seen after 16 years of biennial screening of younger women are assessed in this prospective cohort study. Since 1975 some 13,500 women, aged 35-49 in 1975, were invited to participate in the Nijmegen screening programme comprising a mammographic examination every 2 years. By the end of 1990, 75 women had died of breast cancer out of the 332 cases diagnosed after the start of the screening project. Women from the same birth cohort, living in Arnhem, a neighbouring city with a comparable population and without a screening project, were used as controls. In this city, 74 breast cancer deaths out of 284 cases occurred during the same period. In Nijmegen, after 16 years of follow-up, breast cancer mortality showed a non-significant reduction of 6% (95% confidence interval: 32% reduction, 29% excess). In the relevant period, after a time lag of 10 years from the start of the programme, this reduction rose to 20% (95% confidence interval: 48% reduction, 23% excess). No reduction in breast cancer mortality was observed in the first decade of screening. For a later period, a shift towards a reduction emerges, but the data are as yet inconclusive.

Adult↗
PubMed1995

Work environment and prostate cancer risk.

A case-referent study of 345 prostate cancer cases and 1,346 referents was carried out in the Netherlands to investigate the relationship between work environment and prostate cancer risk. Cases were selected from the Cancer Registry of the Comprehensive Cancer Centre IKO. Referents (men diagnosed with benign prostate hyperplasia) were recruited with assistance of the pathology laboratories in the IKO region. Questionnaires were mailed to all subjects to obtain information on their work history and occupational exposure. Moreover, workers in farming (n = 323), and in metal work and maintenance (n = 340), were requested to complete short supplements to the questionnaire inquiring in more detail into specific types of exposure. Significantly elevated risks were found for work in food manufacturing and for bookkeepers. Significantly elevated odds ratios (OR) were also observed for jobs held between 1960 and 1970 in administration, in storage, or as farm laborer. In addition, a statistically significant excess risk was found for subjects who reported frequent occupational exposure to cadmium. Cases who worked in farming applied pesticides during significant more days per year than the referents did. A nonsignificantly elevated OR was found for maintenance of tractors and agricultural machinery. Among metal workers, mechanics, and repairmen, nonsignificantly increased ORs were observed with regard to the use of acids, solvents, iron, and steel, and for welding and maintenance of machinery.

Aged↗
PubMed1995

Age at menarche and breast cancer risk in nulliparous women.

Early age at menarche is a known risk factor for breast cancer, some inconsistency in the literature not withstanding. Relative risks for an early menarcheal onset as compared to a late onset vary from 1.0 to 1.9. To avoid (residual) confounding by parity-related factors a case-control study was conducted among nulliparous women. 135 cases and 540 controls were selected from two population-based screening projects for breast cancer in The Netherlands. Four controls were matched to each case for year of birth, for screening-centre, and for number of screening examinations. Women with a menarcheal age of 10 or 11 years showed a 2.2 times (95% confidence interval: 1.2-4.0) higher risk for breast cancer compared to women who had their first menstrual period at 12 years of age or older.

Adolescent↗
PubMed1995

Problems in selecting the adequate patient population from existing data files for assessment studies of new diagnostic tests.

Assessment of new diagnostic tests should be carried out in a population with suspicion of disease. This 'indicated' population may comprise all patients for whom the target disease is part of the differential diagnosis. To investigate this empirically, data from a study on ultrasonography for scrotal pathology diagnosis was used for assessment of ultrasonography for epididymitis. The population could be selected according to several inclusion criteria, varying from patients with epididymitis mimicking diseases in their differential diagnosis, to patients with only epididymitis mentioned in their differential diagnosis. Different methods of population gathering led to large variations in the test characteristics of ultrasonography (sensitivity 76-83%, specificity 79-97%, prevalence of epididymitis for test-negative patients 56-5%). These results suggest selection bias depending on the true disease status. We advocate prospective assessment studies in populations with disease suspicion, as defined by signs, symptoms and complaints. Constituting an indicated population from an existing file of retrospectively gathered data may pose problems.

Adolescent↗
PubMed1995

An addition to the controversy on sunlight exposure and melanoma risk: a meta-analytical approach.

Case control studies on the association between sunlight exposure and melanoma risk show considerable differences in design; this could be responsible for the variation in study results. In an attempt to resolve the controversy between study results, the results of 25 publications on case control studies were evaluated using meta-analytical techniques. Comparison of odds ratios between subgroups of studies revealed that the range of odds ratios was far greater for hospital-based studies than for population-based studies. For the latter type of studies, the odds ratios were homogeneous and the pooled odds ratios were 1.57 (95% confidence interval [CI], 1.29-1.91) for intermittent sunlight exposure and 0.73 (95% CI, 0.60-0.89) for chronic exposure. However, among other problems, the lack of standardized measures for sunlight exposure warrants cautious interpretation of these results. It is concluded that evidence to support the intermittent sunlight theory is still far from complete.

Case-Control Studies↗
PubMed1995

Guidelines for the assessment of new diagnostic tests.

RATIONALE AND OBJECTIVES: Because new diagnostic tests become available rapidly, the authors determined a need for proper assessment of tests before their implementation in clinical practice. Three factors are of pivotal importance: the selection of the proper study population, the determination of the diagnostic power including its related statistical analysis, and the relation of the new test to current diagnostic tools. Patients suspected of having a disease are those who would benefit from the application of a new test. Therefore, only those patients need be involved in the assessment study. METHODS: Summary measures of diagnostic power other than sensitivity and specificity are advocated because these conventional measures depend on cutoff points and are susceptible to selection bias. The relation between the new test and existing diagnostic tools must be established to determine if the new test contributes to the diagnostic process. RESULTS AND CONCLUSION: To avoid waste of effort and money, the authors suggest a prudent assessment approach in phases. Whereas the initial challenge consists of selection of an adequate patient population, subsequently all determinants of diseases (signs, symptoms, comorbidity, and other diagnostic factors) and factors influencing the decision to use a test (patient burden and cost) are considered.

Bayes Theorem↗
PubMed1995

Sample size determination for a trial of breast cancer screening under age 50: population versus case mortality approach.

OBJECTIVE: To determine the efficacy of screening for breast cancer in women aged 40 to 49. METHODS: A large number of women will have to be enrolled to ensure adequate statistical power. Attention will be restricted to the deaths from breast cancer that occur among comparable groups of patients with breast cancer rather than to an analysis in which all women entering into the trial are considered at risk of dying from breast cancer (population mortality analysis). As the new trial is likely to be conducted in regions where screening has been established for all women from age 50 onward, comparability may be reached by including the breast cancers detected at the routine screening examination at age 50. CONCLUSIONS: When comparability of cases can be reached, such a case mortality analysis requires 15-30% fewer women to be enrolled than a population approach.

Adult↗