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H Straatman

Publications and source records attributed to H Straatman.

60 records · Page 4Linked to original sources
PubMed1990

Analysis and presentation of data on the natural course of otitis media with effusion in children.

Methods of analysing and presenting longitudinal data on health characteristics that have a fluctuating course are by no means standard. Several possibilities are discussed and tried out on longitudinal data on Otitis Media with Effusion (OME) in Dutch children. If the purpose of a study is descriptive, a graphical presentation based on an idea from Fiellau-Nikolajsen is preferred. For estimation purposes on the other hand, hazard functions are the most suitable. Further reduction of the data does not lead to a clear view into the complex nature of the course of a disease such as OME.

Acoustic Impedance Tests↗
PubMed1989

Evaluation of overdiagnosis of breast cancer in screening with mammography: results of the Nijmegen programme.

After 12 years of screening for breast cancer in Nijmegen (1975-86), during which period six mammographic examination rounds were carried out, the extent of overdiagnosis was evaluated. Overdiagnosis is defined as a histologically established diagnosis of invasive or intraductal breast cancer that would never have developed into a clinically manifest tumour during the patient's normal life expectancy if no screening examination had been carried out. The whole 12-year period shows an excess of 11% of breast cancer cases in Nijmegen, compared with the neighbouring city of Arnhem, where no mass screening was performed. The incidence of breast cancers in Nijmegen in the period 1975-78 is higher, compared with the incidence rates in Arnhem; the rate ratio is 1.30. For the time-intervals 1979-82 and 1983-86 the rate ratios are 1.03 and 1.01 respectively with (0.89; 1.18) and (0.86; 1.16) as 95% confidence intervals. This leads to the conclusion that there is no evidence that screening programmes using modern mammography constitute a significant risk for overdiagnosis of breast cancers.

Adult↗
PubMedDate not supplied

Conditions at conception in women with recurrent miscarriage.

In order to evaluate the role of conditions at conception in the risk of miscarriage, we sent 234 women with at least two consecutive miscarriages after conceptions from the same partner a short questionnaire asking for the birth dates of their mothers and their live or stillborn siblings and the occurrence of any maternal miscarriages. Complete information was provided by 186 respondents. Using matched logistic regression, we investigated whether these women were born more often than their siblings (total n = 578) to young (< or = 19 years) or relatively old (> or = 40 years) mothers or shortly after a preceding pregnancy (born within 1 year). We also evaluated whether they showed a different month-of-birth distribution. No increased odds ratios were found for young or advanced maternal age, or for short preceding birth intervals. However, relative to their siblings, cases showed a deviant month-of-birth distribution (p = 0.08) with a peak in (late) winter. These results indicate that low and high maternal age and short preceding birth intervals are not determinants of the risk of miscarriage in the daughter. They also suggest that there may be seasonally varying factors that prenatally influence the risk of miscarriage.

Abortion, Habitual↗
PubMedDate not supplied

ROC curves and the areas under them for dichotomized tests: empirical findings for logistically and normally distributed diagnostic test results.

Many measures, including sensitivity and specificity, predictive values, and likelihood ratios, are available for the assessment of diagnostic tests. A drawback of the use of these measures is that continuous test results are often dichotomized, with consequent loss of information. Receiver operating characteristic (ROC) curves do not depend on discrimination thresholds, and therefore the area under the ROC curve (AUC) is one of the preferred measures. Although quantitative test results are often presented dichotomized, it would be convenient still to be able to estimate the ROC curve and the AUC. The authors present equations for such estimates when only one pair of a true- and a false-positive rate is given, for inherently logistically and normally distributed data. Illustrative empirical data are provided for both distributions. In contradiction to earlier reports, the authors also show that differential disease verification may skew the ROC curve. The ROC curve is thus not invariant to selection bias.

Bayes Theorem↗