Nirupa Dattani

The Impact of the Increasing Number of Multiple Births on the Rates of Preterm Birth and Low Birthweight: An International Study

OBJECTIVES We studied the effects of twins and triplets on perinatal health indicators in the overall population in the 1980s and 1990s in Canada, England and Wales, France, and the United States. METHODS Data were derived mostly from live birth registration. We used rates, relative risks, and population attributable risks for twins and triplets separately. RESULTS In each country, the increase in multiple births, and the increase in preterm delivery among multiple births, contributed almost equally to the rise in or stabilization of the overall rates of preterm delivery. Twins contributed a much larger proportion of the preterm deliveries and low-birthweight newborns than did triplets. CONCLUSIONS Twins have a major population-based impact on the trends of perinatal health indicators.

Linking maternity data for England, 2005-06: methods and data quality

AbstractIntroduction Maternity Hospital Episode Statistics (HES) data were linked to birth registration and NHS Numbers for Babies (NN4B) data to bring together some key demographic and clinical data items not otherwise available at a national level. This project added to earlier work involving linkage of birth registration records to NN4B records. Methods Birth registration and NN4B records were linked to Maternity HES delivery records and also Maternity HES baby records using the NHS Number or other indirect identifiers if NHS Number was missing.Data quality and completeness of Maternity HES were assessed in relation to birth registration data wherever possible. For information not collected at registration, NN4B data were used to validate quality of Maternity HES. Results Overall, 91 per cent of Maternity HES delivery records could be linked to the birth registration/NHS Numbers for Babies records and 84 per cent of Maternity HES baby records were linked.In 2005 only 3 per cent of Maternity HES records had mothers NHS number missing, compared with 30 per cent in the NN4B dataset. This did not reflect the extent to which Maternity HES data items were missing or discordant.Over a quarter of all linked Maternity HES records for singleton babies had one or more of the following data items missing: birthweight, gestational age, birth status, sex, and date of birth of the baby. On the other hand, for data items where information was stated such as birthweight, birth status, and sex for singleton babies, there was good agreement between Maternity HES and linked birth registration and NN4B data.Although NN4B records the ethnic category of the baby as defined by the mother, and Maternity HES records mothers ethnic category, 87 per cent of the linked records had the same ethnic group. Conclusion Even though a good linkage rate was obtained, the method used will be simplified before data for 2007 are linked. To gain the maximum benefit from this linkage in future years, improvements are urgently needed in the quality and completeness of the data contained in Maternity HES. List of Tables, 55

Identifying possible false matches in anonymized hospital administrative data without patient identifiers

OBJECTIVE To identify data linkage errors in the form of possible false matches, where two patients appear to share the same unique identification number. DATA SOURCE Hospital Episode Statistics (HES) in England, United Kingdom. STUDY DESIGN Data on births and re-admissions for infants (April 1, 2011 to March 31, 2012; age 0-1 year) and adolescents (April 1, 2004 to March 31, 2011; age 10-19 years). DATA COLLECTION/EXTRACTION METHODS Hospital records pseudo-anonymized using an algorithm designed to link multiple records belonging to the same person. Six implausible clinical scenarios were considered possible false matches: multiple births sharing HESID, re-admission after death, two birth episodes sharing HESID, simultaneous admission at different hospitals, infant episodes coded as deliveries, and adolescent episodes coded as births. PRINCIPAL FINDINGS Among 507,778 infants, possible false matches were relatively rare (n = 433, 0.1 percent). The most common scenario (simultaneous admission at two hospitals, n = 324) was more likely for infants with missing data, those born preterm, and for Asian infants. Among adolescents, this scenario (n = 320) was more common for males, younger patients, the Mixed ethnic group, and those re-admitted more frequently. CONCLUSIONS Researchers can identify clinically implausible scenarios and patients affected, at the data cleaning stage, to mitigate the impact of possible linkage errors.

Estimating the prevalence of chronic conditions in children who die in England, Scotland and Wales: a data linkage cohort study.

Objectives To estimate the proportion of children who die with chronic conditions and examine time trends in childhood deaths involving chronic conditions. Design Retrospective population-based death cohort study using linked death certificates and hospital discharge records. Setting England, Scotland and Wales. Participants All resident children who died aged 1–18 years between 2001 and 2010. Primary and secondary outcome measures The primary outcome was the proportion of children who died with chronic conditions according to age group and type of chronic condition. The secondary outcome was trends over time in mortality rates involving chronic conditions per 100 000 children and trends in the proportion of children who died with chronic conditions. Results 65.4% of 23 438 children (95% CI 64.8%, 66.0%) died with chronic conditions, using information from death certificates. This increased to 70.7% (95% CI 70.1% to 71.3%) if hospital records up to 1 year before death were also included and was highest (74.8–79.9% depending on age group) among children aged less than 15 years. Using data from death certificates only led to underascertainment of all types of chronic conditions apart from cancer/blood conditions. Neurological/sensory conditions were most common (present in 38.5%). The rate of children dying with a chronic condition has declined since 2001, whereas the proportion of deaths affected by chronic conditions remained stable. Conclusions The majority of children who died had a chronic condition. Neurological/sensory conditions were the most prevalent. Linkage between death certificate and hospital discharge data avoids some of the under-recording of non-cancer conditions on death certificates, and provides a low-cost, population-based method for monitoring chronic conditions in children who die.

Linking databases on perinatal health: a review of the literature and current practices in Europe

Background: International comparisons of perinatal health indicators are complicated by the heterogeneity of data sources on pregnancy, maternal and neonatal outcomes. Record linkage can extend the range of data items available and thus can improve the validity and quality of routine data. We sought to assess the extent to which data are linked routinely for perinatal health research and reporting. Methods: We conducted a systematic review of the literature by searching PubMed for perinatal health studies from 2001 to 2011 based on linkage of routine data (data collected continuously at various time intervals). We also surveyed European health monitoring professionals about use of linkage for national perinatal health surveillance. Results: 516 studies fit our inclusion criteria. Denmark, Finland, Norway and Sweden, the US and the UK contributed 76% of the publications; a further 29 countries contributed at least one publication. Most studies linked vital statistics, hospital records, medical birth registries and cohort data. Other sources were specific registers for: cancer (70), congenital anomalies (56), ART (19), census (19), health professionals (37), insurance (22) prescription (31), and level of education (18). Eighteen of 29 countries (62%) reported linking data for routine perinatal health monitoring. Conclusion: Research using linkage is concentrated in a few countries and is not widely practiced in Europe. Broader adoption of data linkage could yield substantial gains for perinatal health research and surveillance.

Making a hash of data: what risks to privacy does the NHS's care.data scheme pose?

Care.data proposes to link individual level hospital episode statistics (HES) and general practice data at the Health and Social Care Information Centre. As is currently the case for HES, linked data will be pseudoanonymised before being released to researchers.1 A proposed alternative is for identifiers (such as NHS number, date of birth) to be pseudoanonymised at source,2 using an encrypted hash, before linkage is performed.3 4 Pseudoanonymisation …

What can the UK learn from international comparisons of routinely collected perinatal data? UK perspectives on the Euro-Peristat project

Abstract Background Claims that perinatal and infant mortality rates in the UK are higher than those of all comparable countries are often made in a spirit of moral panic, to argue for policies or interventions that may or may not be effective at reducing the rates. Crude perinatal and infant mortality rates tend to be included routinely in successive national and international indicator sets, sometimes being interpreted as measures of population health and sometimes as measures of quality of health care. Such claims inevitably ignore the effect of differences in childbearing populations, data collection methods, and inclusion criteria. The Euro-Peristat project was established to move beyond presentation of unidimensional indicators in isolation and to present data about the outcome of pregnancy for mothers and babies stratified by birthweight and gestational age while presenting comparative data about maternity care and the characteristics of the childbearing population to set them in context. Methods Collaborators from 26 European Union (EU) member states plus Iceland, Norway, and Switzerland took part in the most recent phase. The indicators were selected with a Delphi process for the first data collection for the year 2000 and revised to compile data for 2004 and then 2010. They were designed to be compiled from routine national vital registration, clinical, or administrative data collection systems in the form of cross-tabulations of aggregated anonymised data. Each country provided information about methods of data collection and inclusion criteria. No rankings were applied and the countries were listed alphabetically according to their official EU names. Data were published in the form of graphs of indicators and tables of data. Stillbirth and neonatal mortality rates were calculated with WHO definitions. Where possible, indicators of outcome were constructed with common cutoffs on the basis of gestational age or birthweight, to avoid bias towards higher reported rates in countries in which births and deaths are registered at lower gestational ages. Findings All indicators showed wide variation between countries, although some of this variation could be attributed to differences in data collection and ascertainment. Because of differences in data collection, data for the countries of the UK were compiled separately. Stillbirth rates at or after 28 weeks of gestation ranged from 1·5 per 1000 total births in the Czech Republic to 4·3 per 1000 total births in France, with rates of 3·8 per 1000 total births in England and Wales, 3·6 per 1000 total births in Scotland, and 3·4 per 1000 total births in Northern Ireland being among the higher rates. Neonatal mortality rates at 24 weeks or more of gestation ranged from 0·8 per 1000 livebirths in Iceland and 1·1 per 1000 livebirths in Finland to 4·3 per 1000 livebirths in Romania, with rates of 2·0 per 1000 livebirths in England and Wales, 2·1 per 1000 livebirths in Scotland, and 3·0 per 1000 livebirths in Northern Ireland. Rates for some countries were based on small numbers of events. There were also differences in risk factors. Interpretation The interpretation of these and other indicators are discussed more fully in the first and second European Perinatal Health Report. Infant and perinatal mortality rates in the UK were not the highest in Europe but they were above the median. To be useful for identification of scope for improvements, international comparisons of the outcome of pregnancy should take account of random variation and differences in methods of data collection and population characteristics. Simple league tables based on crude rates are unhelpful. Funding Euro-Peristat is funded by the Health Programme of the European Commissions Directorate General for Health and Consumers. The funding source had no role in the writing of this abstract or the reports on which it is based.

Data on births by ethnic group now available for England and Wales

Raleigh says that ethnic origin is not known for sentinel outcomes—such as the 636 000 births and 470 000 deaths annually in England.1 However, we have just published data by ethnic group on all births in England and Wales in 2005.2 Like the …

Ethnic variation in unexplained deaths in infancy, including sudden infant death syndrome (SIDS), England and Wales 2006–2012: national birth cohort study using routine data

Background Unexplained deaths in infancy comprise ‘sudden infant death syndrome’ (SIDS) and deaths without ascertained cause. They are typically sleep-related, perhaps triggered by unsafe sleep environments. Preterm birth may increase risk, and varies with ethnicity. We aimed to compare ethnic-specific rates of unexplained infant death, explore sociodemographic explanations for ethnic variation, and examine the role of preterm birth. Methods We analysed routine data for 4.6 million live singleton births in England and Wales 2006–2012, including seven non-White ethnic groups ranging in size from 29 313 (Mixed Black-African-White) to 180 265 (Pakistani). We calculated rates, birth-year-adjusted ORs, and effects of further adjustments on the χ2 for ethnic variation. Results There were 1559 unexplained infant deaths. Crude rates per 1000 live singleton births were as follows: 0.1–0.2 for Indian, Bangladeshi, Pakistani, White Non-British, Black African; 0.4 for White British; 0.6–0.7 for Mixed Black-African-White, Mixed Black-Caribbean-White, Black Caribbean. Birth-year-adjusted ORs relative to White British ranged from 0.38 (95% CI 0.24 to 0.60) for Indian babies to 1.73 (1.21 to 2.47) for Black Caribbean (χ2(10 df)=113.6, p<0.0005). Combined adjustment for parents’ marital/registration status and mother’s country of birth (UK/non-UK) attenuated the ethnic variation. Adjustments for gestational age at birth, maternal age and area deprivation made little difference. Conclusion Substantial ethnic disparity in risk of unexplained infant death exists in England and Wales. Apparently not attributable to preterm birth or area deprivation, this may reflect cultural differences in infant care. Further research into infant-care practices in low-risk ethnic groups might enable more effective prevention of such deaths in the general population.

Linkage of Maternity Hospital Episode Statistics data to birth registration and notification records for births in England 2005-2014: methods. A population-based birth cohort study

Introduction Maternity Hospital Episode Statistics (HES) data for 2005–2014 were linked to birth registration and birth notification data (previously known as NHS Numbers for Babies or NN4B) to bring together some key demographic and clinical data items not otherwise available at a national level. The linkage algorithm that was previously used to link 2005–2007 data was revised to improve the linkage rate and reduce the number of duplicate HES records. Methods Birth registration and notification linked records from the Office for National Statistics (‘ONS birth records’) were further linked to Maternity HES delivery and birth records using the NHS Number and other direct identifiers if the NHS Number was missing. Results For the period 2005–2014, over 94% of birth registration and notification records were correctly linked to HES delivery records. Two per cent of the ONS birth records were incorrectly linked to the HES delivery record and 5% of ONS birth records were linked to more than one HES delivery record. Therefore, a considerable amount of time was spent in quality assuring these files. Conclusion The linkage rate for birth registration and notification records to HES delivery records steadily improved from 2005 to 2014 due to improvement in the quality and completeness of patient identifiers in both HES and birth notification data.