Methodological difficulties in the comparison of indicators of perinatal health across Europe

doi:10.1016/j.ejogrb.2003.09.004

European Journal of Obstetrics & Gynecology and Reproductive Biology

Volume 111, Supplement 1, 28 November 2003, Pages S33-S44

https://doi.org/10.1016/j.ejogrb.2003.09.004 Get rights and content

Abstract

The main purpose of this article is to point out common pitfalls that can confuse comparative analyses of indicators of perinatal health and to discuss ways to overcome or minimize these difficulties. The challenge is to distinguish ‘real’ variations in the value of an indicator from variations due to differences in registration practices and definitions and from random variation. The first section presents the major properties that are desirable in indicators of perinatal health status and perinatal health care in Europe to be used for comparative purposes. The second section provides specific examples of the types of methodological difficulties encountered in European cross-country comparisons due to variations in the definition, measurement and construction of indicators. The conclusion discusses the PERISTAT project’s responses to these difficulties and how these methodological constraints impact on the selection of an appropriate indicator set for Europe today.

Section snippets

Optimal properties of indicators of perinatal health and care

It is good practise to begin by determining the characteristics of ideal indicators and then to use these as guidelines for selecting or constructing performance measures. Generally, good indicators are expected to be representative, useful, precise, highly sensitive, readily accessible, valid, specific, unbiased and reliable. Last but not least, the entire set of indicators should be comprehensive, that is, it should cover all aspects of the field of interest.

Indicators of health and health

Variation in Europe-wide indicators due to differences in registration, definition, measurement and precision: examples

European indicators do not always fulfil all the desired criteria described in Section 1: differences in health systems and health reporting systems throughout Europe present major challenges to the construction of comparable indicators. The following examples illustrate the impact of differences in the measurement and construction of these indicators on their values.

Conclusions and practical recommendations

The recommendations of the PERISTAT scientific advisory committee were made in light of these methodological difficulties in cross-European comparisons. The SAC aimed to minimize these methodological problems for the set of indicators it established, both through its selection process and its recommendations about the computation and presentation of indicators.

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Cited by (31)

International Ranking of Infant Mortality Rates: Taiwan Compared with European Countries
2016, Pediatrics and Neonatology
Citation Excerpt :
A recent study suggested that the survival rate of very low birth weight infants was higher than that observed in the USA, but lower than Canada and Japan.11 However, many scholars indicated the presence of bias, such as the variation in registration of live births and stillbirths among countries, in comparisons of infant mortality rates among countries.12–25 Therefore, the World Health Organization (WHO) recommended restricting international comparisons of infant mortality rates to comparing live births with a known birth weight of at least 1000 g.26 Despite this suggestion, information on the number of live births with a birth weight < 1000 g is not readily available for many countries, which hinders valid international comparisons.
Rankings of infant mortality rates are commonly cited international comparisons to assess the health status of individual countries. We compared the infant mortality rate of Taiwan with those of European countries for 2004 according to two definitions.
First, the countries were ranked on the basis of crude infant, neonatal, and postneonatal mortality rates. The countries were then ranked according to the mortality rates calculated after exclusion of live births with a known birth weight of <1000 g, which is the definition set by the World Health Organization.
Taiwan was ranked 11^th, 12^th, and 15^th among 26 high-income countries for crude infant, neonatal, and postneonatal mortality rates, respectively. The ranks were 12^th, 16^th, and 15^th, respectively, for mortality rates, excluding live births with a birth weight of <1000 g. However, in only seven, four, and 10 countries were the mortality rate ratios statistically significantly lower than Taiwan in infant, neonatal, and postneonatal mortality, respectively, according to the second definition.
The ranking of Taiwan was similar (11^th vs. 12^th) according the two definitions. However, after consideration of the confidence interval, only six countries (Sweden, Finland, Czech Republic, Belgium, Austria, and Germany) had infant mortality rates statistically significantly lower than those of Taiwan in 2004.
The European perinatal health report: Delivering comparable data for examining differences in maternal and infant health
2009, European Journal of Obstetrics and Gynecology and Reproductive Biology
In December 2008, the first-ever European Perinatal Health Report was released by EURO-PERISTAT. Part of the EU Health Programme for health surveillance and reporting, this landmark report presents indicators of perinatal health and care derived from routine statistical data in 25 EU Member States and Norway. It also includes chapters from three other European projects with perinatal data: SCPE on cerebral palsy, EUROCAT on congenital anomalies and EURONEOSTAT on very preterm babies admitted to intensive care.
Infant Mortality in Canada
2009, Journal of Obstetrics and Gynaecology Canada
Canada’s infant mortality rates appear to be worsening, but this may be due, at least in part, to inconsistencies in registration of births at the edge of viability, variations in international practices for reporting live births, and related factors. There are striking differences in reported infant mortality rates among provinces and territories and between certain population groups within Canada. Efforts are underway through the Canadian Perinatal Surveillance System, Public Health Agency of Canada, to further improve the reporting of stillbirths and livebirths throughout Canada and to promote accurate reporting of First Nations, Inuit, and Métis births.
Bien que, au Canada, les taux de mortalité infantile semblent s’aggraver, cela pourrait être attribuable (du moins, en partie) à des irrégularités dans l’enregistrement des naissances se situant à la limite de la viabilité, à des variations des pratiques internationales en ce qui concerne le signalement des naissances vivantes et à des facteurs connexes. Des différences remarquables en matière de taux de signalement de la mortalité infantile sont constatées entre les provinces et les territoires, et entre certains groupements de population au Canada. Des efforts sont en cours, par l’intermédiaire du Système canadien de surveillance périnatale (Agence de la santé publique du Canada), en vue d’améliorer davantage le signalement des mortinaissances et des naissances vivantes partout au Canada, ainsi qu’en vue de promouvoir la précision du signalement des naissances au sein des Premières nations et des communautés inuites et métis.
Determinants of increases in stillbirth rates from 2000 to 2010
2013, CMAJ. Canadian Medical Association Journal
Citation Excerpt :
Most pregnancy terminations in our study occurred between 20 and 23 weeks' gestation, whereas some countries (e.g., the UK) consider fetal deaths to be stillbirths only if they occur at 24 weeks' gestation or later. Such variations in definitions and birth registration practices are responsible for changes in the ranking of countries based on crude stillbirth rates versus ranking based on rates of stillbirths with a birth weight of 1000 g or more.16–19 Concerns regarding maternal and fetal health status are not misplaced given recent increases in the frequency of risk factors for adverse perinatal outcomes, including higher maternal age, weight before pregnancy and multiple births.11–13
After decades of decline, stillbirth rates have increased in several industrialized countries in recent years. We examined data from the province of British Columbia, Canada, in an attempt to explain this unexpected phenomenon.
We carried out a retrospective population-based cohort study of all births in British Columbia from 2000 to 2010. Outcomes of interest included overall stillbirth rates, birth weight– and gestational age–specific stillbirth rates, rates of spontaneous stillbirths (excluding pregnancy terminations that satisfied the definition of stillbirth [fetal death with a birth weight ≥ 500 g or gestational age at delivery ≥ 20 wk], hereafter referred to as “pregnancy terminations”) and rates of congenital anomalies among live-born infants. We used logistic regression to adjust for changes in maternal age, parity, weight before pregnancy and multiple births.
Overall, stillbirth rates increased by 31% (95% confidence interval [CI] 13% to 50%), from 8.08 per 1000 total births in 2000 to 10.55 per 1000 in 2010. The rate of stillbirths with a birth weight of less than 500 g increased significantly (p_trend = 0.03), whereas the rate of stillbirths with a birth weight of 1000 g or more decreased significantly (p_trend = 0.009). The rate of spontaneous stillbirths decreased nonsignificantly by 16%, from 5.7 per 1000 total births in 2000 to 4.8 per 1000 in 2010. There was a significant decline of 30% (95% CI 6% to 47%) in the rate of spontaneous stillbirth with a birth weight of 1000 g or more between 2000 and 2010; adjustment for maternal factors did not appreciably change this temporal effect. The prevalence of congenital anomalies among live-born infants decreased significantly, from 5.21 per 100 live births during the first 3 years (2000–02) to 4.77 per 100 during the final 3 years (2008–10).
Increases in pregnancy terminations were responsible for the increases observed in stillbirth rates and were associated with declines in the prevalence of congenital anomalies among live-born infants.
Behind international rankings of infant mortality: How the United States compares with Europe
2010, International Journal of Health Services
Perinatal epidemiology: Issues, challenges, and potential solutions
2021, Obstetric Medicine

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Methodological difficulties in the comparison of indicators of perinatal health across Europe

Abstract

Section snippets

Optimal properties of indicators of perinatal health and care

Variation in Europe-wide indicators due to differences in registration, definition, measurement and precision: examples

Conclusions and practical recommendations

Bjog

Am. J. Obstet. Gynecol.

Bjog

Am. J. Obstet. Gynecol.

Bias in studies of preterm and postterm delivery due to ultrasound assessment of gestational age

Epidemiology