Ruth M. Hadfield

Quality of data in perinatal population health databases: a systematic review.

BackgroundAdministrative or population health datasets (PHDS) are increasingly being used for research related to maternal and infant health. However, the accuracy and completeness of the information in the PHDS is important to ensure validity of the results of this research. ObjectiveTo compile and review studies that validate the reporting of conditions and procedures related to pregnancy, childbirth, and newborns and provide a tool of reference for researchers. MethodsA systematic search was conducted of Medline and EMBASE databases to find studies that validated routinely collected datasets containing diagnoses and procedures related to pregnancy, childbirth, and newborns. To be included datasets had to be validated against a gold standard, such as review of medical records, maternal interview or survey, specialized register, or laboratory data. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and/or &kgr; statistic for each diagnosis or procedure code were calculated. ResultsForty-three validation studies were included. Under-enumeration was common, with the level of ascertainment increasing as time from diagnosis/procedure to birth decreased. Most conditions and procedures had high specificities indicating few false positives, and procedures were more accurately reported than diagnoses. Hospital discharge data were generally more accurate than birth data, however identifying cases from more than 1 dataset further increased ascertainment. ConclusionsThis comprehensive collection of validation studies summarizing the quality of perinatal population data will be an invaluable resource to all researchers working with PHDS.

The accuracy of reporting of the hypertensive disorders of pregnancy in population health data.

Objective. To assess the accuracy of hypertensive disorders of pregnancy reporting in birth and hospital discharge data compared with data abstracted from medical records. Methods. Data from a validation study of 1200 women provided the ‘gold standard’ for hypertension status. The validation data were linked to both hospital discharge and birth databases. Hypertension could be reported in one, both, or neither database. Results. Of the 1184 records available for review, 8.3% of women had pregnancy-related hypertension and 1.3% had chronic hypertension. Reporting sensitivities ranged from 23% to 99% and specificities from 96% to 100%. Using broad rather than specific categories of hypertension and more than one source to identify hypertension improved case ascertainment. Women with severe preeclampsia or adverse outcomes were more likely to have their pregnancy-related hypertension reported. When the hypertension reporting was discordant on the birth and hospital discharge data, the hospital data were more accurate. Conclusions. Pregnancy-related hypertension is reported with a reasonable level of accuracy, but chronic hypertension is markedly under-ascertained, even when cases were identified from more than one source. Milder forms of hypertension are more likely to go unreported. Studies utilizing population health data may overestimate the proportion of more severe forms of disease and any risk these conditions contribute to other outcomes.

How accurate is the reporting of obstetric haemorrhage in hospital discharge data? A validation study.

Background: Routinely collected datasets are frequently used for population‐based research but their accuracy needs to be assured.

The prevalence of maternal medical conditions during pregnancy and a validation of their reporting in hospital discharge data.

Population health datasets are a valuable resource for studying maternal and obstetric health outcomes. However, their validity has not been thoroughly examined. We compared medical records from a random selection of New South Wales (NSW) women who gave birth in a NSW hospital in 2002 with coded hospital discharge records. We estimated the population prevalence of maternal medical conditions during pregnancy and found a tendency towards underreporting although specificities were high, indicating that false positives were uncommon.

Is there an association between endometriosis and the risk of pre-eclampsia? A population based study

BACKGROUND An association between endometriosis and reduced risk of pre-eclampsia has recently been reported. Longitudinally-linked electronic hospital records are a valuable resource for investigating such findings in a large, population-based sample. Our aim was to determine whether women with a history of endometriosis were at modified risk for pregnancy hypertension or pre-eclampsia. METHODS A population-based, longitudinal study of all women in the Australian state of New South Wales, aged from 15 to 45 years of age with a singleton birth during the period 2000-2005. Endometriosis was identified using ICD-10 codes. Endometriosis subgroups were analysed based on: (i) site of endometriosis (ovary or peritoneum), (ii) multiple (i.e. two or more) sites affected and (iii) infertility. To investigate the association between pregnancy hypertension and endometriosis, number of weeks gestation at birth and maternal age, we used logistic regression. RESULTS In the 3239 (1.6%) women with endometriosis diagnosed before their first birth, 352 (10.9%) had a diagnosis of pregnancy hypertension compared with 23,186/205,640 (11.3%) in women with no endometriosis diagnosis (OR 0.96; 95% CI 0.9-1.3). The frequency of pregnancy hypertension and pre-eclampsia was not significantly different in women with more severe endometriosis or endometriosis in conjunction with infertility when compared with those with no endometriosis. After adjusting for maternal age and weeks gestation there was still no altered risk. CONCLUSIONS We have found no evidence for an association between endometriosis and subsequent risk of either pregnancy hypertension or pre-eclampsia in this large population-based dataset.

Sleep Apnea in Early Childhood Associated with Preterm Birth but Not Small for Gestational Age: A Population-Based Record Linkage Study

STUDY OBJECTIVES Investigate the relationship between gestational age and weight for gestational age and sleep apnea diagnosis in a cohort of children aged up to 6 years old. DESIGN A cohort study, using record linked population health data. SETTING New South Wales, Australia. PARTICIPANTS 398,961 children, born between 2000 and 2004, aged 2.5 to 6 years. MEASUREMENTS The primary outcome was sleep apnea diagnosis in childhood, first diagnosed between 1 and 6 years of age. Children with sleep apnea were identified from hospital records with the ICD-10 code G47.3: sleep apnea, central or obstructive. RESULTS A total of 4,145 (1.0%) children with a first diagnosis of sleep apnea were identified. Mean age at first diagnosis was 44.2 months (SD 13.9). Adenoidectomy, tonsillectomy, or both were common among the children diagnosed with sleep apnea (85.6%). Children born preterm compared to term were significantly more likely to be diagnosed with sleep apnea (< 32 weeks versus term hazard ratio 2.74 [95% CI: 2.16, 3.49]) this remained even after adjustment for known confounding variables. Children born small for gestational age were not at increased risk of sleep apnea compared to children born appropriate for gestational age, hazard ratio 0.95 (95% CI 0.86-1.06). CONCLUSIONS This is the largest study investigating preterm birth and sleep apnea diagnosis and suggests that diagnosis of sleep disordered breathing is more prevalent in children born preterm, but not those who are small for gestational age.

Levels of soluble fms-like tyrosine kinase one in first trimester and outcomes of pregnancy: a systematic review.

Angiogenic factors are involved in formation of new blood vessels required for placental development and function; and critical for fetal growth and development. Soluble fms-like tyrosine kinase 1(sFlt-1) is an anti-angiogenic protein that inhibits formation of new blood vessels resulting in potential pregnancy complications. The objective of this study was to undertake a systematic review to assess levels of sFlt-1 in early pregnancy and association with adverse pregnancy outcomes. PubMed and Medline databases and reference lists were searched up to July 2010. Inclusion criteria were pregnant women, blood sample taken during first trimester and assessment/reporting of sFlt-1 concentrations and subsequent pregnancy complications. Twelve relevant studies were identified of 71 to 668 women. No pooling of results was undertaken due to variation in sFlt-1 concentrations (range, 166-6,349 pg/ml amongst controls), samples used (serum, plasma), different summary statistics (mean, median, odds ratio) and outcome definitions applied. Levels of sFlt-1 were generally higher among women who developed preeclampsia (11 studies) or gestational hypertension (two studies), but not significantly different to normotensive women in most studies. There was no consistent pattern in association between sFlt-1 concentrations and fetal growth restriction (4 studies); and levels were non-significantly higher for women with postpartum bleeding (1 study) and significantly lower for stillbirths (1 study).This review found no clear evidence of an association between sFlt-1 levels in first trimester and adverse pregnancy outcomes. However, findings were affected by methodological, biological and testing variations between studies; highlighting the need for consistent testing of new biomarkers and reporting of outcome measures.

Trends in obstetric practices and meconium aspiration syndrome: a population‐based study

Please cite this paper as: Vivian‐Taylor J, Sheng J, Hadfield R, Morris J, Bowen J, Roberts C. Trends in obstetric practices and meconium aspiration syndrome: a population‐based study. BJOG 2011;118:1601–1607.

Trends in the use of epidural analgesia in Australia

To investigate whether changes in maternal and birth characteristics explain the increase in the use of epidural analgesia during labor.

A prevalence survey of every-day activities in pregnancy

BackgroundResearch into the effects of common activities during pregnancy is sparse and often contradictory. To examine whether common activities are an acute trigger of pregnancy complications the prevalence of these activities are necessary to determine sample size estimates. The aim of this study is to ascertain the prevalence of selected activities in any seven day period during pregnancy.MethodsThe study was conducted in the antenatal clinic of a teaching hospital with tertiary obstetric and neonatal care in Sydney, Australia between August 2008 and April 2009. Women who were at least 20 weeks pregnant and able to read English completed a questionnaire to assess whether they had performed a list of activities in the seven days prior to survey completion. Results were analysed using frequency tabulations, contingency table analyses and chi square tests.ResultsA total of 766 surveys were completed, 29 surveys were excluded as the women completing them were less than 20 weeks pregnant, while 161 women completed the survey more than once. Ninety seven per cent of women completed the survey when approached for the first time, while 87% completed the survey when approached a subsequent time. In the week prior to completing the survey 82.6% of women had consumed a caffeinated beverage, 42.1% had had sexual intercourse, 32.7% had lifted something over 12 kilograms, 21.4% had consumed alcohol and 6.4% had performed vigorous exercise. The weekly prevalence of heavy lifting was higher for multiparous women compared to nulliparous women.ConclusionsThe results of this study can be used to inform future research into activities as acute triggers of pregnancy complications.