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To gain insight into the performance of deterministic record linkage (DRL) vs. probabilistic record linkage (PRL) strategies under different conditions by varying the frequency of registration errors and the amount of discriminating power. A simulation study in which data characteristics were varied to create a range of realistic linkage scenarios. For each scenario, we compared the number of misclassifications (number of false nonlinks and false links) made by the different linking strategies: deterministic full, deterministic N-1, and probabilistic. The full deterministic strategy produced the lowest number of false positive links but at the expense of missing considerable numbers of matches dependent on the error rate of the linking variables. The probabilistic strategy outperformed the deterministic strategy (full or N−1) across all scenarios. A deterministic strategy can match the performance of a probabilistic approach providing that the decision about which disagreements should be tolerated is made correctly. This requires a priori knowledge about the quality of all linking variables, whereas this information is inherently generated by a probabilistic strategy. PRL is more flexible and provides data about the quality of the linkage process that in turn can minimize the degree of linking errors, given the data provided.

Background Perinatal mortality is an important indicator of health. European comparisons of perinatal mortality show an unfavourable position for the Netherlands. Our objective was to study regional variation in perinatal mortality within the Netherlands and to identify possible explanatory factors for the found differences. Methods Our study population comprised of all singleton births (904,003) derived from the Netherlands Perinatal Registry for the period 2000–2004. Perinatal mortality including stillbirth from 22 +0 weeks gestation and early neonatal death (0–6 days) was our main outcome measure. Differences in perinatal mortality were calculated between 4 distinct geographical regions North-East-South-West. We tried to explain regional differences by adjustment for the demographic factors maternal age, parity and ethnicity and by socio-economic status and urbanisation degree using logistic modelling. In addition, regional differences in mode of delivery and risk selection were analysed as health care factors. Finally, perinatal mortality was analysed among five distinct clinical risk groups based on the mediating risk factors gestational age and congenital anomalies. Results Overall perinatal mortality was 10.1 per 1,000 total births over the period 2000–2004. Perinatal mortality was elevated in the northern region (11.2 per 1,000 total births). Perinatal mortality in the eastern, western and southern region was 10.2, 10.1 and 9.6 per 1,000 total births respectively. Adjustment for demographic factors increased the perinatal mortality risk in the northern region (odds ratio 1.20, 95% CI 1.12–1.28, compared to reference western region), subsequent adjustment for socio-economic status and urbanisation explained a small part of the elevated risk (odds ratio 1.11, 95% CI 1.03–1.20). Risk group analysis showed that regional differences were absent among very preterm births (22 +0 – 25 +6 weeks gestation) and most prominent among births from 32 +0 gestation weeks onwards and among children with severe congenital anomalies. Among term births (≥ 37 +0 weeks) regional mortality differences were largest for births in women transferred from low to high risk during delivery. Conclusion Regional differences in perinatal mortality exist in the Netherlands. These differences could not be explained by demographic or socio-economic factors, however clinical risk group analysis showed indications for a role of health care factors.

BackgroundEthnic disparities in perinatal mortality are well known. This study aimed to explore the contribution of demographic, socioeconomic, health behavioural and pre-existent medical risk factors among different ethnic groups on fetal and early neonatal mortality.MethodsWe assessed perinatal mortality from 24.0 weeks' gestation onwards in 554 234 singleton pregnancies of nulliparous women in the linked Netherlands Perinatal Registry over the period 2000–2006. Logistic regression modelling was used.ResultsConsiderable ethnic differences in perinatal mortality exist especially in fetal mortality. Maternal age, socioeconomic status and pre-existent diseases could not explain these ethnic differences. Late booking visit could explain some differences. Compared with the Dutch, African women had an increased fetal mortality risk of OR 1.7 (95% CI 1.4 to 2.1); South Asian women, 1.8 (1.4 to 2.3); other non-Western women, 1.3 (1.1 to 1.6) and Turkish/Moroccan women, 1.3 (1.1 to 1.4). The risk on early neonatal mortality was only increased in other non-Western women, OR 1.3 (1.0 to 1.8). Ethnic differences were even present in the women without risk factors including preterm births. Mortality risk for East Asian and other Western women was lower or comparable with the Dutch.ConclusionImportant ethnic differences in fetal mortality exist, especially among women of African and South Asian origin. Ethnic minorities should be more acquainted with the significance of early start of prenatal care. Tailored prenatal care for women with African and South Asian origin seems necessary. More research on underlying cause of deaths is needed by ethnic group.

Background:The European PERISTAT-1 study showed that, in 1999, perinatal mortality, especially fetal mortality, was substantially higher in The Netherlands than in other European countries. The aim of this study was to analyse the recent trend in Dutch perinatal mortality and the influence of risk factors.Methods:A nationwide retrospective cohort study of 1 246 440 singleton births in 2000–2006 in The Netherlands. The source data were available from three linked registries: the midwifery registry, the obstetrics registry and the neonatology/paediatrics registry. The outcome measure was perinatal mortality (fetal and early neonatal mortality). The trend was studied with and without risk adjustment. Five clinical distinct groups with different perinatal mortality risks were used to gain further insight.Results:Perinatal mortality among singletons declined from 10.5 to 9.1 per 1000 total births in the period 2000–2006. This trend remained significant after full adjustment (odds ratio 0.97; 95% CI 0.96 to 0.98) and was present in both fetal and neonatal mortality. The decline was most prominent among births complicated by congenital anomalies, among premature births (32.0–36.6 weeks) and among term births. Home births showed the lowest mortality risk.Conclusions:Dutch perinatal mortality declined steadily over this period, which could not be explained by changes in known risk factors including high maternal age and non-western ethnicity. The decline was present in all risk groups except in very premature births. The mortality level is still high compared with European standards.

WE would like to respond to an article, concerning exposure to radon gas, which was published in the South China Morning Post on...