Association between perinatal mortality and morbidity and customised and non-customised birthweight centiles in Denmark, Finland, Norway, Wales, and England: comparative, population based, record linkage study.

Objectives: To compare the risk of adverse perinatal outcomes according to infants who are born small for gestational age (SGA; <10th centile) or large for gestational age (LGA; >90th centile), as defined by birthweight centiles that are non-customised (ie, standardised by sex and gestational age only) and customised (by sex, gestational age, maternal weight, height, parity, and ethnic group). Design: Comparative, population based, record linkage study with meta-analysis of results. Setting: Denmark, Finland, Norway, Wales, and England (city of Bradford), 1986-2019. Participants: 2 129 782 infants born at term in birth registries. Main outcome measures: Stillbirth, neonatal death, infant death, admission to neonatal intensive care unit, and low Apgar score (<7) at 5 minutes. Results: Relative to those infants born average for gestational age (AGA), both SGA and LGA births were at increased risk of all five outcomes, but observed relative risks were similar irrespective of whether non-customised or customised charts were used. For example, for SGA versus AGA births, when non-customised and customised charts were used, relative risks pooled over countries were 3.60 (95% confidence interval 3.29 to 3.93) versus 3.58 (3.02 to 4.24) for stillbirth, 2.83 (2.18 to 3.67) versus 3.32 (2.05 to 5.36) for neonatal death, 2.82 (2.07 to 3.83) versus 3.17 (2.20 to 4.56) for infant death, 1.66 (1.49 to 1.86) versus 1.54 (1.30 to 1.81) for low Apgar score at 5 minutes, and (based on Bradford data only) 1.97 (1.74 to 2.22) versus 1.94 (1.70 to 2.21) for admission to the neonatal intensive care unit. The estimated sensitivity of combined SGA or LGA births to identify the three mortality outcomes ranged from 31% to 34% for non-customised charts and from 34% to 38% for customised charts, with a specificity of 82% and 80% with non-customised and customised charts, respectively. Conclusions: These results suggest an increased risk of adverse perinatal outcomes of a similar magnitude among SGA or LGA term infants when customised and non-customised centiles are used. Use of customised charts for SGA/LGA births-over and above use of non-customised charts for SGA/LGA births-is unlikely to provide benefits in terms of identifying term births at risk of these outcomes.

Agreement between the Danish Cancer Registry and the Danish Colorectal Cancer Group Database.

Background: The Danish Cancer Registry (DCR) and the Danish Colorectal Cancer Group (DCCG) database are population-based registries collecting information on Danish patients with colorectal cancer (CRC). DCR registers all patients with incident CRC whereas DCCG records patients with first time CRC. The registries use different inclusion criteria. The consequencenses of this are unknown and not previously evaluated. The aim of this study was to examine the agreement between patients registered in DCR and DCCG and to evaluate its influence on estimated survival and mortality.Material and methods: Patients registered in DCR and DCCG with CRC in 2014-2015 were included. Because of different inclusion criteria, DCCG's inclusion criteria were applied to DCR. Descriptive statistics were used for comparisons. One-year relative survival (1-year RS) was calculated, and the Cox proportional hazard model used for calculating 1-year mortality rate ratios (1-year MRR).Results: In 2014-2015, DCR registered 9678 Danish residents with CRC that fulfilled DCCG's inclusion criteria, while DCCG registered 10,312 Danish residents with CRC. Allowing ±180 days between dates of diagnosis, 10,688 patients were registered with CRC in the merger of the two registries. Of these, 86% were included in both registers, 4% only in DCR, and 10% only in DCCG. No difference was found in 1-year RS between patients in DCR 86% (95% CI: 85-87) and DCCG 85% (95% CI: 84-86). However, patients registered in DCCG had a 1-year MRR of 1.09 (95% CI: 1.01-1.17) compared to DCR.Conclusion: An agreement of 86% of patients was found between the two registries. The discrepancy did not influence 1-year RS. DCCG registered more patients than DCR, and 1-year MRR of patients in DCCG was increased compared to patients in DCR. Regular linkage of the registries is recommended to improve data quality of both registries.

Nordic Cancer Registries - an overview of their procedures and data comparability.

BACKGROUND: The Nordic Cancer Registries are among the oldest population-based registries in the world, with more than 60 years of complete coverage of what is now a combined population of 26 million. However, despite being the source of a substantial number of studies, there is no published paper comparing the different registries. Therefore, we did a systematic review to identify similarities and dissimilarities of the Nordic Cancer Registries, which could possibly explain some of the differences in cancer incidence rates across these countries. METHODS: We describe and compare here the core characteristics of each of the Nordic Cancer Registries: (i) data sources; (ii) registered disease entities and deviations from IARC multiple cancer coding rules; (iii) variables and related coding systems. Major changes over time are described and discussed. RESULTS: All Nordic Cancer Registries represent a high quality standard in terms of completeness and accuracy of the registered data. CONCLUSIONS: Even though the information in the Nordic Cancer Registries in general can be considered more similar than any other collection of data from five different countries, there are numerous differences in registration routines, classification systems and inclusion of some tumors. These differences are important to be aware of when comparing time trends in the Nordic countries.