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Biomedical subjects

A L Verbeek

Publications and source records attributed to A L Verbeek.

At least 73 records · Page 4Linked to original sources
PubMed1997

Breast-cancer mortality in a non-randomized trial on mammographic screening in women over age 65.

Recent case-referent studies in the Nijmegen breast-screening programme have shown a reduction in breast-cancer mortality of approximately 50% due to screening of women aged 65 years and older. In this type of study, however, the results may be biased because of self-selection. The purpose of our present study was to compare the breast-cancer mortality rate in a population invited for screening with that of a reference population from an area without a screening programme. In 1977-1978, 6773 women aged 68-83 years were enrolled in the mammographic screening programme in Nijmegen, The Netherlands. The women were followed up until 31 December, 1990. The reference population consisted of women from the same birth cohort from Arnhem, a neighbouring city without mass screening, for whom the entry date was 1 January, 1978. The ratios of the Nijmegen and Arnhem breast-cancer mortality rates with 95% confidence intervals (CI) were calculated. In the study period, 173 patients were diagnosed with primary breast cancer in Nijmegen vs. 183 in Arnhem; 40 Nijmegen patients had died of breast cancer vs. 51 Arnhem patients. The cumulative mortality-rate ratio was 0.80 (95% CI = 0.53-1.22). In the periods 1978-1981, 1982-1985 and 1986-1990, the mortality rate ratios were 1.44 (95% CI = 0.67-3.10), 081 (95% CI = 0.37-1.79) and 0.53 (95% CI = 0.27-1.04), respectively. After adjustment for the difference in incidence rate that existed between the Nijmegen and Arnhem populations, mammographic screening of women older than 65 can be expected to yield a 40% reduction in breast-cancer mortality after 10 years.

Aged↗
PubMed1997

Quality assessment by expert opinion in melanoma pathology: experience of the pathology panel of the Dutch Melanoma Working Party.

Some cutaneous melanocytic lesions are notoriously difficult to diagnose by histopathology. For that reason, the Pathology Panel of the Dutch Melanoma Working Party was instituted and is regularly approached to provide an expert opinion on problem cases. In order to identify the most common diagnostic problems, 1069 consecutive referral cases of submitted lesions (1992 to 1994 inclusive) were analysed. About 60 per cent of the requests came from small laboratories, with up to three consultant pathologists. Two-thirds of the lesions reviewed concerned women and nearly 50 per cent of the patients were 30 years of age or younger. In 8 per cent of the cases, the referring pathologists felt unable to make a confident diagnosis; in 14 per cent, melanoma was suspected; and in 12 per cent, a differential diagnosis only had been formulated. The panel felt able to provide an unequivocal diagnosis in 93 per cent of the requests. Of the 158 lesions classified as 'invasive melanoma' by the referring pathologists, 22 were considered to be benign by the panel. Conversely, 108 invasive melanomas (panel diagnosis) had originally been considered as benign lesions, dysplastic naevi or melanoma in situ. These high numbers of discordancies reflect the intrinsic difficulty of the differential diagnoses in this selected material submitted to the panel. Diagnostic difficulties were most often encountered with Spitz naevi and dysplastic naevi. Although the rate of overdiagnosis and underdiagnosis is quite high, in the majority of cases the diagnosis of the referring pathologist matched the diagnosis of the panel. This may reflect a proper awareness of difficult melanocytic lesions in pathology practice. The activities of the Pathology Panel of the Dutch Melanoma Working Party contribute to the improvement of the quality of diagnosis in cutaneous melanocytic lesions, as they increase the number of unequivocal diagnoses and reduce the number of incorrect diagnoses. On the basis of the systematic comparison of the diagnosis by the referring pathologist and the panel, postgraduate teaching and quality control can be more focused on specific diagnostic problems.

Adolescent↗
PubMed1997

Heterogeneity of spina bifida.

Splitting birth defects into dysmorphologically homogeneous groups might improve the ability to detect a genetic risk factor or teratogenic exposure. With regard to spina bifida, recent studies suggest that etiologic heterogeneity exists within the group of spina bifida, although exogenous risk factors have been sparsely evaluated for subgroups. In the present study, 210 spina bifida patients were classified into relatively homogeneous groups, based on retrospective information on appearance and functional aspects of the lesion abstracted from medical records of the patients. We compared high with low spina bifida, and open with closed spina bifida, and investigated whether risk factors for spina bifida such as maternal age, antiepileptic drug use, parental occupation, and genetic factors were specifically associated with these homogeneous subclasses. For these comparisons, a referent group of 671 children was used. Although classifying spina bifida into homogeneous subclasses presented some difficulties and numbers were small, this study provides some evidence for different risk profiles for subclasses of spina bifida. The sex ratio, the proportion of miscarriages of siblings, and maternal age did not differ among the different subclasses of spina bifida. However, children with a positive family history of neural tube defects (NTDs) had a higher risk of high spina bifida [odds ratio (OR) = 6.3, 95% confidence interval (CI): 1.7-19.2] than of low spina bifida (OR = 2.1, 95% CI: 1.0-4.2). Siblings with NTDs were more common in cases with high spina bifida and cases with open spina bifida. A strongly increased risk of high spina bifida was found for male welders (OR = 12.1, 95% CI: 1.5-64.2), whereas the risk of low spina bifida was much lower (OR = 1.6, 95% CI: 0.2-7.9). For mothers with agricultural occupations, a strongly increased risk was observed for open spina bifida (OR = 14.3, 95% CI: 2.9-77.7), whereas none of 107 cases with closed spina bifida had a mother with an occupation in agriculture. Due to small numbers, the results must be interpreted with caution.

Adult↗
PubMed1997

Paternal occupational exposure around conception and spina bifida in offspring.

A multi-center case-referent study was conducted on the relation between paternal occupational exposure and spina bifida in offspring. Cases were born between 1980 and 1992 in The Netherlands. Referents were recruited from hospitals and from the general population. Postal questionnaires were used to gather information on occupation and potential confounders. Through job-specific telephone interviews with 122 case fathers and 411 referent fathers, detailed exposure information was collected on specific tasks, the use of chemical or physical agents, frequency of exposure, and use of protective equipment. The study yielded statistically significant associations between spina bifida and low exposure to welding fumes (OR = 1.6, 95% CI: 1.0-2.6) and low exposure to UV radiation during welding (OR = 2.6, 95% CI: 1.2-5.6), and suggestive findings of an association between spina bifida and moderate or high exposure to cleaning agents, moderate or high pesticide exposure (OR = 1.7, 95% CI: 0.7-4.0), and stainless steel dust (OR = 2.0, 95% CI: 0.8-5.2). No associations were identified for other paternal occupational exposures, such as organic solvents.

Case-Control Studies↗
PubMed1997

Prognostic significance of etiological risk factors in early breast cancer.

Several risk factors for the etiology of breast cancer have also been correlated with the prognosis of breast cancer. However, the published studies have yielded conflicting results. Women under 71 years of age with stage I, II, or III breast cancer were eligible for inclusion in a clinical study. 866 patients with breast cancer entered the study, of whom 463 had positive lymph nodes. Survival was analysed using Cox's proportional hazards model. Age at menarche parity, age at menopause and family history were not consistently related to survival. Young age at first full-term pregnancy was related to decreased survival (adjusted relative risk (RR): 1.69, 95% confidence intervals (95% CI): 1.04-2.68), but it cannot be excluded that this result was due to chance alone. Use of oral contraceptives was not correlated with survival (RR: 1.10, 95% CI: 0.80-1.51) nor was family history (RR: 0.93, 95% CI: 0.66-1.30). This study provided little support for the hypothesis that risk factors for breast cancer are related to survival.

Adult↗
PubMed1997

Management in general practice of patients with persistent dyspepsia. A decision analysis.

To determine whether an empirical drug treatment strategy (empirical group) instead of upper gastrointestinal endoscopy followed by treatment (conventional group) in patients with persistent dyspepsia increases appropriate use of endoscopy facilities, we did a decision analysis based on data found in the literature. We estimated the percentage of patients having an upper gastrointestinal endoscopy in 1 year, the percentage of patients with symptom relief, and the average medical costs per patient for both groups. In the empirical group, fewer patients (38%) had upper gastrointestinal endoscopies compared with the conventional group. Furthermore, an additional 5% of patients in the empirical group experienced symptom relief, and the average medical costs per patient were estimated to be 8% less in this group when compared with the patients in the conventional treatment group. The proposed empirical drug treatment strategy for patients with persistent dyspepsia results in the performance of fewer diagnostic upper gastrointestinal endoscopies per year with greater effectiveness compared with upper gastrointestinal endoscopy followed by treatment.

Decision Trees↗
PubMed1997

Assessment of occupational exposure in a population based case-control study: comparing postal questionnaires with personal interviews.

BACKGROUND: In case-control studies, data collection on occupational exposures by means of personal interviews is usually costly and time consuming. As detailed semiquantitative information on exposure from these interviews often has to be dichotomised in the analyses due to the small numbers of exposed subjects, the question is raised whether simple postal questionnaires yield the same results for occupational exposure in epidemiological studies as job specific personal interviews. METHODS: Data on occupational exposures during pregnancy were compared from 121 women who both completed a checklist with 17 occupational exposure categories in a postal questionnaire and were personally interviewed with specific questions on exposure with details of job and task. kappa Coefficients were calculated as measures of agreement corrected for chance, and sensitivity and positive predictive values as measures of validity and usefulness, with the exposure assessment based on information from the interview as the gold standard. RESULTS: Values of kappa varied from 0.09 for domestic cleaning agents to 0.70 for pesticides, indicating only low to moderate agreement between the questionnaire and the interview. Sensitivity ranged from 38% to 100%, with the highest values for agents used by healthcare workers. Positive predictive values were lower, between 9% and 63%, which indicates that overreporting was more common than underreporting in the questionnaire. CONCLUSIONS: These results underline the high potential for misclassification of occupational exposure in studies based on questionnaires. Therefore, postal questionnaires are not considered an alternative to job and task specific personal interviews in epidemiological studies.

Adult↗
PubMed1997

Mammographic screening in older women. Is it worthwhile?

The optimal upper age limit in mammographic screening for breast cancer is still a matter for debate. The incidence of breast cancer rises gradually with increasing age and, without screening, breast cancer in elderly women is diagnosed at a more advanced stage than in younger women. After menopause, much of the glandular tissue of the breast is replaced by fat, which facilitates the mammographic detection of breast cancer in older women. Furthermore, the tumour growth rate decreases with increasing age. Recently, a reduction in breast cancer mortality due to mammographic screening has been shown for women aged up to 75 years. There is a lack of data for women over the age of 75 years, however, because the number of women screened in the only study that included this age category is too small to give reliable results. We conclude that mammographic screening is beneficial at least up to the age of 75 years, and may also be beneficial up to age 85 years in healthy women with a good life expectancy.

Aged↗
PubMed1997

Estimating lead time and sensitivity in a screening program without estimating the incidence in the screened group.

Early indicators of the effectiveness of a screening test for chronic diseases such as breast cancer are the length of time the diagnosis is advanced by screening, the lead time, and the sensitivity of the screening test. This paper describes a model for simultaneously estimating the mean lead time and the sensitivity when only the number of cancers detected at the successive screenings and the number of cancers occurring in the time interval between the screening examinations are known. This model is particularly useful in assessing the effect of screening when the underlying cancer incidence in the screened group is unknown. The model is fitted to the data of 235 screen-detected breast cancer cases and 146 interval cancers diagnosed across 6 screening rounds of the program in Nijmegen. The maximum likelihood estimate for the mean lead time ranges from 1.3 years in the under age 50 group to 2.2 years in the age 50-65 group, both estimates having large confidence intervals. The corresponding sensitivity estimates are 0.92 and 1.00.

Adult↗
PubMed1997

Breast cancer epidemiology and risk factors.

Breast cancer is the most common malignancy among women in the Western society. Over the past decades it has become apparent that breast cancer incidence rates are increasing steadily, whereas the mortality rates for breast cancer have remained relatively constant. Information through the media on this rising number of cases has increased breast health awareness but has also introduced anxiety in the female population. This combination of factors has made the need for prevention of breast cancer an urgent matter. Breast cancer does not seem to be a single disease entity. A specific etiologic factor may therefore have more influence on one form of breast cancer than another. So far though, as shown in our summary of current knowledge on established and dubious risk factors, no risk factors have been identified that can explain a major part of the incidence. Efforts to identify other ways for primary prevention have also been discouraging, even though breast cancer is one of the most investigated tumours world-wide. Thus, at this point in time, the most important strategy to reduce breast cancer mortality is early detection through individual counselling and organised breast screening programs. The recent isolation of breast cancer susceptibility genes may introduce new ways to reduce the risk of breast cancer in a small subset of women.

Adult↗
PubMed1997

Comparison of four 'second generation' immunoassay systems to determine CA 125 in serum by using a graphical approach to method comparison analysis.

Clinical management of ovarian cancer patients is facilitated by CA 125 determinations in serum. Presently, several assay systems based on different concepts and different methodologies are available to measure CA 125. Method comparison analysis of such assay systems is usually performed through (linear) regression analysis, which requires assumptions about the distribution of experimental data and its measurement error. The aim of the present study was to compare four newly developed second generation assay systems for quantitation of CA 125 by utilizing an alternative simple approach to method comparison analysis. This alternative comprises the construction of relative difference plots and mountain plots, previously described by Krouwer et al. (Eur J Clin Chem Clin Biochem 1995; 33:525-7). In addition, the diagnostic value of the assays was illustrated through receiver-operating-characteristic (ROC) curves. Sera obtained from 300 women were assayed for CA 125 using the Abbott IMx CA 125 assay (Abbott), the Centocor CA 125 II RIA assay (Centocor), the Berilux Ov testing kit for CA 125 (Behringwerke), and the CA 125 TR-FIA assay (Wallac Oy). Both the relative difference plots and the mountain plots revealed higher serum concentrations with the Centocor RIA II (Median +33%, P2.5 to P97.5: -25% to 161%) and Berilux (Median +28%, P2.5 to P97.5: -17% to 108%) compared to the Abbott IMx system. The TR-FIA assay system showed lower serum concentrations (Median - 17%, P2.5 to P97.5: -74% to 229%). The combination of relative difference plots and mountain plots demonstrated clearly the wide range of differences between CA 125 assays measuring the same analyte. The relative difference plots provided insight into the distribution of the differences over the range of measurement as well as the identification of outliers. A simple quantitative assessment of the median differences could be made from the overlaying mountain plots. The close correspondence observed between the ROC curves illustrated that assay systems for CA 125 differing in design (type of antibodies used) and format can produce similar results on group level. However, the results of the clinical evaluation underline the importance of the application of assay specific cut-off values.

Adolescent↗
PubMed1996

[Shortening of therapy duration in patients with pulmonary tuberculosis from 9 to 6 months only justifiable on the basis of published data].

OBJECTIVE: To determine if in the Netherlands, just like in other countries, the treatment of pulmonary tuberculosis with adequately sensitive tubercle bacilli may be shortened from 9 to 6 months. DESIGN: Literature study. SETTING: Municipal Health Service, Nijmegen, the Netherlands. METHOD: The relevant literature was analysed, using the percentage of recurrences as the criterion. The study was restricted to patients with pulmonary tuberculosis in whom the diagnosis had been confirmed bacteriologically and in whom a human, normally sensitive tubercle bacillus had been isolated. The treatment schedule had to include at least isoniazid, rifampicin and pyrazinamide. There were no studies with treatment of 9 months' duration. The studies with 6 months' treatment were selected on the basis of the predetermined criteria from among articles included in Medline in 1980-1991. RESULTS: The treatment schedules of 6 months' duration (n = 44) from 25 articles were suitable for analysis. Treatment for 6 months' resulted in a proportion of recurrences of tuberculosis of 2.4% (95%-confidence interval: 2.0-2.8), with follow-up periods of 12 to 94 months after discontinuation of the treatment. Addition of streptomycin or ethambutol during the initial phase, self-medication or controlled treatment, daily or intermittent treatment made no difference as regards the ultimate results. No comparison with the proportion of recurrences of 1% (0.2-2.9) after 9 month's treatment without pyranizamide was possible. A recent calculation of the number of Dutch nationals with recurrent tuberculosis resulted in a proportion of recurrences of 2.5 (1.8-3.2). The guideline adopted was that mentioned by the American Thoracic Society, a proportion of recurrences of < 5%. CONCLUSION: On the basis of the known percentages of recurrence, it could be decided in the Netherlands as well to shorten the duration of treatment from 9 to 6 months.

Antitubercular Agents↗
PubMed1996

Mammographic screening after the age of 65 years: evidence for a reduction in breast cancer mortality.

We evaluated whether regular mammographic screening of women aged 65 years or older affected breast cancer mortality. In Nijmegen, a population-based screening program for breast cancer was started in 1975, with biennial mammography for women aged 35-64 years. Since 1977, elderly women have also been participating. For the present case-control study, women were selected who were over 64 years of age at the most recent invitation. Eighty-two of them had died from breast cancer. For these cases, 410 age-matched population controls were selected. The ratio of breast cancer mortality rates of the women who had participated regularly (ie., in the 2 most recent screening rounds prior to diagnosis) vs. the women who had not participated in the screening was 0.56 (95% CI = 0.28-1.13). The rate ratio was 0.45 in the women aged 65-74 years at the most recent invitation (95% CI = 0.20-1.02), whereas it was 1.05 in the women aged 75 years and older (95% CI = 0.27- 4.14). While the breast cancer survival rate of the non-participant patients was fairly equal to that of patients from a control population, the underlying incidence rate of breast cancer was higher in the participants than in the non-participants. Therefore, we conclude that bias was present, but that it had decreased our effect estimate. The real reduction in breast cancer mortality due to regular screening will be even larger. Regular mammographic screening of women over age 65 (at least up to 75 years) can reduce breast cancer mortality by approximately 45%.

Aged↗
PubMed1996

Visual hallucinations in psychologically normal people: Charles Bonnet's syndrome.

BACKGROUND: Charles Bonnet's Syndrome (CBS), characterised by the presence of complex visual hallucinations in psychologically normal people, was considered for a long time to be rare. Systematic research on CBS has been limited. However, it has been realised that CBS occurs frequently in elderly, visually handicapped patients, and we have been able to study the syndrome in a large number of patients. METHODS: After screening 505 visually handicapped patients, 60 were found to meet proposed diagnostic criteria for CBS (generally, the existence of hallucinations without delusions or loss of insightful cognition.) Psychopathological characteristics, personal meaning, and the emotional impact of hallucinations, as well as factors influencing the hallucinations, were analysed. FINDINGS: Although diagnostic criteria demand merely "partial insight", all patients had full insight into the unreal nature of their hallucinations. Other characteristics varied. In 46 (77%) patients, hallucinations lacked a personal meaning. Sensory deprivation and a low level of arousal seemed to favour the occurrence of hallucinations. CBS caused considerable distress in only 17 (28%) patients. However, all patients were glad to be told that their hallucinations were not due to mental disease. The proper diagnosis had been made in only one of the 16 patients who had consulted a doctor. INTERPRETATION: Although largely unrecognised in clinical practice, CBS should be considered as a diagnosis in patients who complain of hallucinations and who meet defined diagnostic criteria. There is no proven treatment, but many patients will benefit from reassurance that their hallucinations do not imply mental illness.

Aged↗
PubMed1996

Age-specific sensitivities of mammographic screening for breast cancer.

The sensitivity of the mammographic screening test in the biennial screening program of Nijmegen is assessed by analyzing the occurrence of interval cancers, i.e. cancers surfacing clinically in the interval between a negative screening examination and the subsequent scheduled examination. The difference between the observed number of interval cancers and the expected number of clinically manifest cancers in the absence of screening for the interval period reflects the number of cancers detected by screening. The expected number should be limited by the number of those cancers that were not detectable at the time of the screening examination because their size was under the threshold of mammographic detectability (5 mm). In contrast to other sensitivity studies we took these 'fast growing' cancers into consideration, the numbers of which are estimated in each of the six-month periods of the two-year interval using age-specific tumor volume growth rates for three age groups: < 50, 50-69, and > or = 70 years. In patients under age 50, the sensitivity was 64% for cancers which would become clinically manifest within one year after screening. This sensitivity was lower than those obtained from the 50-69 and > or = 70 age groups, being 85% and 80%, respectively. For cancers that would become clinically manifest 12-18 months after screening, sensitivity decreases to 22% in the under age 50 group, and to 56% and 65% in the two above age 50 groups, respectively. We conclude that even when adjusted for growth rate, the mammographic screening test has a poor performance in the under age 50 group.

Adult↗
PubMed1996

Ovarian cancer incidence (1989-1991) and mortality (1954-1993) in The Netherlands.

OBJECTIVE: To examine ovarian cancer incidence and mortality in the Netherlands, and to relate trends in mortality to changes in parity and use of oral contraceptives. METHODS: Age-standardized and age-specific incidence and mortality rates are presented using incidence data from the Netherlands Cancer Registry, 1989-1991, and mortality data from the Netherlands Central Bureau of Statistics, 1954-1993. RESULTS: In the period 1989-1991, age-standardized incidence of ovarian cancer was 14.9 per 10(5) woman-years. The majority (89%) of these tumors had an epithelial origin. Two-thirds of all newly diagnosed ovarian cancers already showed extension to the pelvis or beyond at diagnosis. From the period 1954-1958 to 1969-1973, age-standardized mortality rates increased from 10.6 to 13.1 per 10(5) woman-years. Thereafter, a decline was noted to 11.4 per 10(5) woman-years in the period 1989-1993. Age-specific mortality rates showed a pattern of rising mortality in the elderly, whereas mortality in the younger age categories was declining. The number of live births has declined gradually, and oral contraceptive use has increased. CONCLUSION: Incidence of ovarian cancer is high in the Netherlands, but comparable to other countries in north-western Europe and North America. Mortality rates are rising in the elderly and declining in the young. Further research is needed concerning the effects of oral contraceptives, fertility drugs, and hormone replacement therapy on the incidence and mortality of ovarian cancer.

Adult↗
PubMed1996

Walking ability of stroke patients: efficacy of tibial nerve blocking and a polypropylene ankle-foot orthosis.

OBJECTIVE: To investigate the efficacy of tibial nerve blocking by percutaneous radiofrequency thermocoagulation and an ankle-foot orthosis on the walking ability of stroke patients with a spastic equinus or equinovarus foot. DESIGN: A placebo-controlled randomized clinical trial with a 2 x 2 factorial design and with a 3-month follow-up. SETTING: Outpatient clinic of a department of rehabilitation medicine. SUBJECTS: Sixty stroke patients (17 women, 43 men) with a median age of 58 years and a median period of 34 months poststroke were allocated to one of four treatment groups. MAIN OUTCOME MEASURES: Changes in walking ability (measured with the Sickness Impact Profile category "ambulation"; possible score range, 0% to 100%) and walking speed after 3 months. RESULTS: With respect to walking ability, the efficacy of thermocoagulation as compared with placebo thermocoagulation was .56% (95% confidence interval [CI] -3.01% to 4.13%), whereas the efficacy of the ankle-foot orthosis as compared with the placebo ankle-foot orthosis was 2.72% (95% CI -.94% to 6.38%). To study the potential synergistic effect of both treatments, a multivariate model was used; interaction between both treatments was small, .83% (95% CI -6.73% to 8.40%). Analysis restricted to the compliers (n = 30) showed an increased efficacy of thermocoagulation and a decreased efficacy of the ankle-foot orthosis. The changes in comfortable and maximal safe walking speed were less than .10m/sec and were neither clinically nor statistically significant (the median baseline values for the total group were .42m/sec and .56m/sec, respectively). CONCLUSION: No support was found for the beneficial effects of either thermocoagulation of the tibial nerve or a polypropylene ankle-foot orthosis in 5 degrees of dorsiflexion on the walking ability of stroke patients.

Adolescent↗