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Paul H Verkerk

Publications and source records attributed to Paul H Verkerk.

8 recordsLinked to original sources
PubMed2006

Reference chart for relative weight change to detect hypernatraemic dehydration.

OBJECTIVE: The validity of the rule of thumb that infants may have a weight loss of 10% in the first days after birth is unknown. We assessed the validity of this and other rules to detect breast-fed infants with hypernatraemic dehydration. DESIGN: A reference chart for relative weight change was constructed by the LMS method. The reference group was obtained by a retrospective cohort study. PARTICIPANTS: 1544 healthy, exclusively breast-fed infants with 3075 weight measurements born in the Netherlands and 83 cases of breast-fed infants with hypernatraemic dehydration obtained from literature. RESULTS: The rule of thumb had a sensitivity of 90.4%, a specificity of 98.3% and a positive predictive value of 3.7%. Referring infants if their weight change is below -2.5 SDS (0.6th centile) in the reference chart in the first week of life and using the rule of thumb in the second week had a sensitivity of 85.5%, a specificity of 99.4% and a positive predictive value of 9.2%. CONCLUSIONS: The rule of thumb is likely to produce too many false positive results, assuming that for screening purposes the specificity needs to be high. A chart for relative weight change can be helpful to detect infants with hypernatraemic dehydration.

Breast Feeding↗
PubMed2006

An interval scale for development of children aged 0-2 years.

Measurement of development is often less precise than that of height and weight. Developmental scores are typically based on passing one or more developmental markers, but do not have interval scale so calculating differences between scores can be nonsensical. Age-specific standardized scores are sometimes used, but fail to have a common metric that allows comparison of developmental scores across age. The goal of this study is to develop a quantitative developmental score (D-score) with improved measurement characteristics. The basic assumption of the D-score is the existence of a common continuous scale for the development. Scores of 2151 children between 0 and 2 years on a Dutch developmental instrument were analysed. Application of the Rasch Model resulted in excellent reliability and satisfactory fit. This indicates that the new quantitative D-score succeeds in representing outcomes of the instrument on a common interval scale. Age-conditional reference values for the D-score were derived by means of the LMS method. The definition of the D-scores is not specific to age, so the D-score of a measured person can be compared to the D-score of another person of a different age. Difference scores between sessions can be used to evaluate developmental velocity on the individual level. To our knowledge this is the first developmental scale for children with such properties.

Child Development↗
PubMed2006

Cost-effectiveness of 4 neonatal screening strategies for cystic fibrosis.

OBJECTIVES: The purpose of this work was to assess the costs of 4 neonatal screening strategies for cystic fibrosis in relation to health effects. In each strategy, the first test was the measurement of serum concentration of immunoreactive trypsin. The second step consisted of either a second immunoreactive trypsin test (strategy 1) or a multiple mutation analysis (strategy 2). In strategies 3 and 4, a third step was added to strategy 2: a second immunoreactive trypsin test (strategy 3) or an extended mutation analysis of the cystic fibrosis gene, that is, a denaturing gradient gel electrophoresis analysis (strategy 4). METHODS: We conducted an economic-modeling exercise in the Netherlands based on published data and expert opinions. Subjects were a hypothetical cohort of 200 000 neonates, the approximate number of children born annually in the Netherlands, and we assessed the costs and number of life-years gained as a result of neonatal screening for cystic fibrosis. The costs and effects of changes in reproductive decisions because of neonatal screening were also assessed. RESULTS: Immunoreactive trypsin + immunoreactive trypsin had the most favorable cost-effectiveness ratio of 24,800 euro per life-year gained. Immunoreactive trypsin + DNA + denaturing gradient gel electrophoresis achieved more health effects than immunoreactive trypsin + DNA + immunoreactive trypsin at lower cost. The incremental costs per life-year gained of the immunoreactive trypsin + DNA + denaturing gradient gel electrophoresis strategy compared with the immunoreactive trypsin + immunoreactive trypsin strategy were 130,700 euro, whereas the incremental costs of the immunoreactive trypsin + DNA strategy compared with the immunoreactive trypsin + DNA + denaturing gradient gel electrophoresis strategy were 2,154,300 euro. When changes in reproductive decisions as a result of neonatal screening are also taken into account, neonatal screening for cystic fibrosis may lead to financial savings of approximately 1.8 million euro annually, depending on the screening strategy used. CONCLUSIONS: Cystic fibrosis screening for neonates is a good economic option, and positive health effects can also be expected. Immunoreactive trypsin + immunoreactive trypsin and immunoreactive trypsin + DNA + denaturing gradient gel electrophoresis are the most cost-effective strategies.

Cost-Benefit Analysis↗
PubMed2005

Cutoff levels of 17-alpha-hydroxyprogesterone in neonatal screening for congenital adrenal hyperplasia should be based on gestational age rather than on birth weight.

OBJECTIVE: In newborn screening programs for congenital adrenal hyperplasia, 17-alpha-hydroxyprogesterone (17OHP) cutoff levels are based on birth weight (BW) or on gestational age (GA). We investigated which approach would result in the greatest specificity and sensitivity. STUDY DESIGN: For the determination of 17OHP, a neonatal 17OHP assay was used in filter paper blood of 9492 newborns. The relationships between 17OHP and BW and between 17OHP and GA were studied by regression analysis. Reference curves with a specificity of 99.95% were constructed with the method that summarizes the distribution by three smoothed curves representing the skewness (L curve), the median (M curve), and the coefficient of variation (S curve). Median cutoff levels for BW and for GA according to the 99.95% reference curves were calculated. RESULTS: Regression analysis showed that GA is a better predictor of 17OHP than BW (R(2) was 50.6 vs. 35.8%, respectively). At a specificity of 99.95%, the calculated median 17OHP cutoff level was lower for GA [12.6 microg/liter (38 nmol/liter)] than for BW [17.6 microg/liter (54 nmol/liter)], thus leading to a greater sensitivity. CONCLUSION: This study demonstrates that GA is a better predictor of 17OHP in newborns and will result in greater specificity than BW despite the fact that the determination of GA might be less reliable than BW.

17-alpha-Hydroxyprogesterone↗
PubMed2005

Neonatal detection of congenital hypothyroidism of central origin.

Due to the high frequency of concurrent pituitary hormone deficiencies, congenital hypothyroidism (CH) of central origin (CH-C) is a life-threatening disorder. Yet only a minority of these patients are detected by neonatal CH screening programs worldwide. We conducted a prospective multicenter study involving a 2-yr cohort of neonatally diagnosed CH-C patients to determine whether a T(4)-TSH-based neonatal CH screening protocol extended with T(4) binding globulin determinations improves early detection of CH-C and to assess the extent of pituitary hormone deficiency among the identified CH-C patients. In all infants with screening results indicative of CH-C, the functional integrity of the hypothalamo-hypophyseal system was investigated by dynamic tests; the anatomical integrity was investigated by magnetic resonance imaging. Initial test results were evaluated after 5 yr of follow-up. Among 385,000 infants screened over the 2-yr period, 19 cases of permanent CH-C were detected (prevalence, 1:20,263; 95% confidence interval, 1:12,976 to 1:33,654), representing 13.5% of all detected cases of permanent CH. The majority (78%) had multiple pituitary hormone deficiency, whereas 53% had pituitary malformations on magnetic resonance imaging. We conclude that infants with CH-C can very well be detected by neonatal screening. The estimated prevalence and the severity of pituitary dysfunction of this treatable disorder call for explicit attention for this entity of CH in neonatal screening programs worldwide.

Adrenocorticotropic Hormone↗
PubMed2005

Clinical effectiveness and cost-effectiveness of the use of the thyroxine/thyroxine-binding globulin ratio to detect congenital hypothyroidism of thyroidal and central origin in a neonatal screening program.

CONTEXT: Since the introduction of screening for congenital hypothyroidism (CH) in 1974, the optimal laboratory strategy has been the subject of debate. OBJECTIVE: To assess the clinical effectiveness and cost-effectiveness of various types of thyroxine (T(4))-based strategies to screen for CH. DESIGN, SETTING, AND PARTICIPANTS: In the Netherlands, since January 1, 1995, a primary T(4) determination with supplemental thyroid-stimulating hormone (TSH) and T(4)-binding globulin (TBG) measurements has been used. Results were calculated from cumulative findings for 1181079 children screened between January 1, 1995, and December 31, 2000. MAIN OUTCOME MEASURES: Rates of detection of patients with CH of thyroidal origin (CH-T) or CH of central origin (CH-C), false-positive rates, laboratory costs, and costs of initial diagnostic evaluations. RESULTS: All known infants (n = 393) with CH-T and 92% (n = 66) of infants with CH-C were detected on the basis of low T(4) levels, TSH elevation, and/or low T(4)/TBG ratios. If the decision to refer had been based solely on TSH elevation, then 94% of patients with CH-T and none of the patients with CH-C would have been detected. If low T(4) levels (<or=-3.0 SD) and TSH elevation had been used as the criteria for referral, then the rates of detection would have been 96% for CH-T and 31% for CH-C. The false-positive rates for the 3 approaches were 0.5, 3.3, and 4.7 cases per case detected, respectively. The introduction of the T(4)/TBG ratio into a program using a primary T(4) with supplemental TSH approach generates an extra cost of 11206 dollars per additional case detected. The average costs to detect 1 patient are comparable for the 3 approaches. In addition, our data revealed a substantially greater prevalence of CH-C than reported previously (1 case per 16404 children, compared with earlier estimates of 1 case per 26000 infants to 1 case per 29000 infants). CONCLUSIONS: The T(4) plus TSH plus TBG approach is a recommendable strategy for neonatal CH screening. It offers outstanding detection of patients with CH-C, in addition to those with CH-T, with acceptable costs.

Congenital Hypothyroidism↗