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H Straatman

Publications and source records attributed to H Straatman.

At least 37 records · Page 2Linked to original sources
PubMed1999

Comparison of immunohistochemistry with immunoassay (ELISA) for the detection of components of the plasminogen activation system in human tumour tissue.

Enzyme-linked immunosorbent assay (ELISA) methods and immunohistochemistry (IHC) are techniques that provide information on protein expression in tissue samples. Both methods have been used to investigate the impact of the plasminogen activation (PA) system in cancer. In the present paper we first compared the expression levels of uPA, tPA, PAI-1 and uPAR in a compound group consisting of 33 cancer lesions of various origin (breast, lung, colon, cervix and melanoma) as quantitated by ELISA and semi-quantitated by IHC. Secondly, the same kind of comparison was performed on a group of 23 melanoma lesions and a group of 28 breast carcinoma lesions. The two techniques were applied to adjacent parts of the same frozen tissue sample, enabling the comparison of results obtained on material of almost identical composition. Spearman correlation coefficients between IHC results and ELISA results for uPA, tPA, PAI-1 and uPAR varied between 0.41 and 0.78, and were higher for the compound group and the breast cancer group than for the melanoma group. Although a higher IHC score category was always associated with an increased median ELISA value, there was an overlap of ELISA values from different scoring classes. Hence, for the individual tumour cases the relation between ELISA and IHC is ambiguous. This indicates that the two techniques are not directly interchangeable and that their value for clinical purposes may be different.

Enzyme-Linked Immunosorbent Assay↗
PubMed1999

Evaluation of treatment regimens to cure Helicobacter pylori infection--a meta-analysis.

OBJECTIVE: To assess effectiveness of treatment to cure Helicobacter pylori infection. DATA SYNTHESIS: Meta-analysis of 666 manuscripts (full papers, abstracts, letters to the editor) identified through Medline and a manual search (1986 to January 1998). Data were overviewed by regression analysis with weighted random effects models. SUBJECTS: 53 228 patients with H. pylori infection. INTERVENTIONS: Patients were treated with 132 different medication combinations. MAIN OUTCOME MEASURE: Cure of H. pylori infection per protocol and intention-to-treat basis at least 28 days after treatment. RESULTS: The nationality of the patients and therapeutic regimen have a significant impact on the results, after correction for the heterogeneity in the precision of the cure rate caused by different study sizes and random effect for study. On the basis of the original sample size, cure rates of 80-85% were achieved using combinations of a proton-pump inhibitor or ranitidine bismuth citrate with two antibiotics including clarithromycin, amoxycillin and metronidazole or tinidazole. Comparable cure rates were also achieved using a combination of a proton-pump inhibitor or H2-receptor antagonist with bismuth subcitrate or tripotassium dicitrato bismuthate, metronidazole and tetracycline. The dose of clarithromycin influenced cure rates. Treatment duration did not influence the outcome. CONCLUSION: Several therapeutic regimens are eligible to cure H. pylori infection. However, none of the medication combinations were able to cure H. pylori infection in more than 85% of the patients assessed by intention-to-treat. The countries in which the studies were performed also had a significant impact on eradication rates.

Antacids↗
PubMed1999

Mortality trend from cancer of the gastric cardia in The Netherlands, 1969-1994.

BACKGROUND: Time trends of cancer of the gastric cardia differ between populations and the reasons are not fully understood. The object of this study was to investigate the occurrence of cancer of the gastric cardia in descriptive relation to age at death, calendar period, birth cohort and gender in the Netherlands between 1969 and 1994. METHODS: Data on the number of people with cancer of the gastric cardia as the underlying cause of death from 1969 to 1994 were obtained from annual publications by the National Causes of Death Registry of Statistics Netherlands. To estimate the separate effects of age, calendar period and birth cohort on the trend in mortality, a simultaneous analysis of these factors was performed using a log-linear Poisson model. RESULTS: In 1969, the mortality rates from cancer of the gastric cardia for males and females per 100,000 people were 2.1 and 1.1; in 1994 the mortality rates were 1.5 and 0.7, respectively. Examination of the time trend suggested that mortality for cancer of the gastric cardia may reflect a period phenomenon, although a cohort effect may have also contributed to the observed time trend. Furthermore, more males than females died from cancer of the gastric cardia. The difference was most striking in the younger age categories. CONCLUSION: In this Dutch population, the age-period-cohort-gender analysis indicated that the mortality rates decreased after the period 1975-1979 which might be explained by a decrease in exposure to risk factor(s) or an increase in exposure to protective factor(s).

Adult↗
PubMed1999

Increased risk of fatal prostate cancer may explain the rise in mortality in The Netherlands.

BACKGROUND: Several lines of evidence suggest that, as a result of improved diagnostic techniques, the increase in incidence of prostate cancer is due largely to increased detection of subclinical cases. Between 1971 and 1989, a considerable increase in incidence was found in Southeastern Netherlands among men aged under 60 years without an improvement in prognosis. We hypothesized that in addition to the increase due to increased detection, a genuine increase in incidence has occurred in the last two decades and that this should be reflected in national mortality rates. METHODS: Age-specific and age-adjusted mortality rates were calculated to determine whether mortality due to prostate cancer continued to increase after 1990. Using log-linear Poisson modelling according to Clayton and Schifflers, we estimated the contribution of period and cohort effects to prostate cancer mortality between 1955 and 1994. RESULTS: The age-adjusted mortality increased from 22 in 1955-1959 to 33 per 10(5) in 1990-1994 (European standardized rate). For men under 65, the rates stabilized after 1989. The age-cohort model fitted the data better than the age-period model. Therefore, the increase in mortality can be explained largely by the increasing risk for successive birth cohorts for men born until 1930. However, more frequent reporting of prostate cancer as the underlying cause of death (partly attributable to a decline in competing causes of death) may have occurred as well. CONCLUSIONS: Our findings suggest an increased risk of fatal prostate cancer in The Netherlands between 1955 and 1994.

Aged↗
PubMed1999

Changes in mammographic breast density and concomitant changes in breast cancer risk.

Among participants of the biennial Nijmegen breast cancer screening programme, we examined whether diminution of mammographic breast density lowered breast cancer risk. Post-menopausal breast cancer cases (n = 108), who had to have participated in all the five screening rounds prior to their diagnosis, were matched to 400 controls on year of birth and screening history. Controls had to be free of breast cancer at the time of the case's diagnosis. Changes in breast density were measured over a 10-year period, by a fully computerized method. Women in whom 5-25% or >25% of the breast was composed of fibro-glandular density showed a threefold increased 10-year risk compared to women with <5% density. In women with 5-25% density initially, we observed a trend of decreasing risk with diminishing density: when women with <5% density throughout the whole period formed the reference category, the odds ratio (OR) for those who decreased from 5-25% to <5% density was 1.9 [95% confidence interval (CI) = 0.6-6.1] in contrast to the OR of 5.7 (95% CI = 2.2-15.2) for those with persisting 5-25% density. In women who increased from 5-25% density to >25% density the OR was 6.9 (95% CI = 2.1-22.9). In women with >25% density initially, diminishing density was not clearly associated with lowering risk, which may be partly explained by the low number of women who decreased to <5% (n = 12). Due to the limited size of the study these results have to be interpreted with caution. Although the results are not conclusive, they could indicate a trend of decreasing risk with diminishing breast density. Should this effect be real, it may have great implications for the primary prevention of breast cancer or for the identification of high-risk groups who would benefit by more frequent screening. Therefore, large-scale, long-term follow-up studies on the effects of changes in breast density are needed.

Adult↗
PubMed1999

Studying seasonality by using sine and cosine functions in regression analysis.

STUDY OBJECTIVE: A statistical test that allows for adjustment of confounding can be helpful for the study of seasonal patterns. The aim of this article is to supply a detailed description of such a method. An example of its application is given. DESIGN: A statistical test is presented that retains the information on the connection of time periods by describing the seasonal pattern as one sine and one cosine function. Such functions can be included into a regression model. The resulting form of the seasonal pattern follows a cosine function with variable amplitude and shift. MAIN RESULTS: The test is shown to be applicable to test for seasonality. Not only one cosine function per time period, but also a mixture of cosine functions can be used to describe the seasonal pattern. Adjustment for confounding effects is possible. CONCLUSIONS: This method for studying seasonal patterns can be applied easily in a regression model. Adjusted prevalences and odds ratios can be calculated.

Confounding Factors, Epidemiologic↗
PubMed1999

Comparison of the CAPAS and Ewing tests for screening of hearing in infants.

OBJECTIVE: To study the similarities and differences between the non-automated labour intensive Ewing hearing test and the less labour intensive automated CAPAS (Compact Amsterdam Paedo-Audiometrical Screening) hearing test. SETTING: A multicentre study in which all the children born in the eastern part of the Netherlands between 1 January 1996 and 1 April 1997 were routinely screened for hearing impairment at 9 months of age. METHODS: Differences and similarities between the two methods were described for the proportion of children who failed every test, the percentage of referred children, the yield of bilateral and unilateral otitis media with effusion (OME), the positive predictive value of the third test result, and the yield of persistent OME after 4-6 months' follow up at an ENT department. RESULTS: 12,603 infants were screened with the CAPAS test and 17,496 with the Ewing test. There were differences between the CAPAS and Ewing tests respectively in the proportions of children lost to follow up (10.1% v 15.2%), the proportions of children referred diagnosed with OME (59% v 81%), the yield of bilateral otitis media with effusion (2.4% v 3.0%), and the yield of persistent OME after 4-6 months' follow up (1.1% v 1.6%). CONCLUSIONS: The CAPAS test is more practical than the Ewing test, but the non-automated Ewing test seems to be more reliable and valid for detecting conductive hearing loss.

Follow-Up Studies↗
PubMed1999

High mammographic breast density and its implications for the early detection of breast cancer.

OBJECTIVES: Women with high mammographic breast density are at increased risk of breast cancer. This study explores whether these women should receive intensified screening (more frequent screening or screening with alternative techniques that increase the length of the preclinical detectable phase) to reduce further breast cancer mortality. METHODS: Mathematical models were used to estimate the effects of intensified screening in women with high breast density. The effects were expressed as a reduction in the number of interval cancers. RESULTS: If women with > 25% breast density (comprising about one fifth of all women) are screened annually instead of biennially, an 18% reduction in the total number of interval cancers can be expected. Screening these women with alternative screening techniques biennially may produce the same reduction, provided that these techniques double the mean lead time. CONCLUSIONS: By screening women with dense breasts more intensively, many more breast cancers can theoretically be detected at an early stage. The results provide an early indication of what may be expected from screening strategies. Next, cost-benefit analyses are needed.

Breast Neoplasms↗
PubMed1999

Kidney cancer mortality in The Netherlands, 1950-94: prediction of a decreasing trend.

BACKGROUND: Incidence and mortality rates of kidney cancer are known to be increasing world-wide. The reasons for these increases are not clear, but despite this it may still be possible to predict changes in the trend of occurrence. METHODS: Male and female kidney (plus ureter and urethra) cancer mortality per 10(5) person-years, from 1950 to 94, were calculated using national demographic and mortality data. Changes in the age structure of the Dutch population were adjusted using direct standardisation to the European standard population. The effects of age, calendar period and birth cohort on the temporal trend in mortality were evaluated using log-linear modelling. RESULTS: Male mortality from kidney cancer increased from three per 10(5) person-years in the 1950s to eight per 10(5) in the mid 1980s and remained relatively stable thereafter. Female mortality rates showed a comparable trend, from two per 10(5) in the 1950s to four per 10(5) in the 1980s. In addition to the effects of age, the temporal trend in males can be sufficiently explained as a birth cohort effect. Successive birth cohorts appear to have higher risks of dying from kidney cancer until the 1930 cohort. The younger birth cohorts appear to have lower risks. The trend in women is comparable to that in men but is less pronounced and shows only after excluding women under the age of 45. CONCLUSION: The decreasing risk for generations born after 1930 will probably result in a decreasing trend in kidney cancer mortality in the near future. It is suggested that at least part of this changing trend in men (but not in women) is caused by the changing smoking behaviour of the Dutch population.

Adolescent↗
PubMed1998

Prognostic factors for otitis media with effusion in infants.

To determine the prognostic factors for otitis media with effusion (OME) in 1-year-old infants, we studied 240 patients and 366 controls in a case-cohort study. On univariate analysis factors which were associated with OME were family history, older siblings, upper respiratory infections and acute otitis media (AOM). After multivariate analysis, however, only the occurrence of more than four upper respiratory infections and children with older siblings were associated with OME. Thus, upper respiratory infections and older siblings appear to be related to the development of OME.

Case-Control Studies↗
PubMed1998

Seasonal variation in human fecundability.

Seasonality of effective fecundability was investigated in a cohort of 402 women born in or near Rotterdam, The Netherlands, between 1873 and 1887, and married before the age of 40 years. Applying a newly developed method allowing simultaneous control for inherent couple fecundability, numbers at risk of pregnancy, and multiple confounders, we found a trend towards higher fecundability during the first half of June and the first half of December (P = 0.06). Seasonality of effective fecundability appeared to be strongest for women who married at <20 years of age. Potentially important implications for the study of seasonality of adverse reproductive outcome are discussed.

Adolescent↗
PubMed1998

External validation of prognostic models for ongoing pregnancy after in-vitro fertilization.

This study aimed to validate prognostic models for predicting ongoing pregnancy after the first and second in-vitro fertilization cycles. Models were developed using data from the University Hospital, Nijmegen, 1991-1994 and tested using more recent data from the same centre and data from two other centres. Although the variables included in the models seemed plausible, the predictions of the models were unsatisfactory. The models did not discriminate between women who had achieved pregnancy and women who did not achieve pregnancy; neither could they indicate which women had a (very) low probability of ongoing pregnancy. Taking into account the success rate of a specific clinic or the success rate during a specific period did not show any advantage. The predictions were even inaccurate in the same hospital during another period. It is obvious that these prognostic models should not be used. This study shows the importance of validating prognostic models before their implementation in clinical practice.

Adult↗
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

Long-term effects of ventilation tubes for persistent otitis media with effusion in children.

The otological, auditory and developmental effects of treatment with ventilation tubes were studied in a sample of 7-8-year-old Dutch children screened for otitis media with effusion (OME) serially at preschool age. Children treated with ventilation tubes were matched retrospectively for OME history, sex, and age with children who were not treated surgically. At the age of 7-8, abnormalities of the tympanic membrane were more prevalent in treated than in untreated ears. No significant differences were found in middle ear function and hearing in both groups. Some positive effects of early surgical intervention on specific developmental measures were found.

Audiometry, Pure-Tone↗
PubMed1997

Is fecundability associated with month of birth? An analysis of 19th and early 20th century family reconstitution data from The Netherlands.

The relationship between fecundability and month of birth was investigated in a cohort of 1526 women who married between 1802 and 1929, using only women whose first marriage occurred before the age of 35 years. On the basis of their time to pregnancy (TTP, calculated as time between wedding and first birth minus gestational length), women were categorized into two groups: fecunds (TTP up to 12 months or prenuptial conceptions, n = 1348) and subfecunds (TTP >18 months, n = 118). By use of logistic regression, cosinor functions with a period of 1 year or 6 months and variable shift and amplitude were fitted through the monthly odds of subfecunds versus fecunds. The best fitting curve was unimodal, with a zenith in September (P = 0.13 for H0: no differences). Exclusion of childless women (n = 36, minimum follow-up 5 years) from the subfecunds led to a similar curve (P < 0.01), while childless women, as compared with fecunds, showed a birth distribution that was best represented with a bimodal curve with zeniths in January and July (P = 0.06). This study provides evidence for the existence of differences in fecundability by month of birth. The cause of this relationship is unclear, but may lie in a melatonin-dependent circannual variability of the quality of the oocyte.

Female↗
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↗
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↗