Methodological approaches to evaluate teratogenic risk using birth defect registries: advantages and disadvantages

Misleading meta-analyses of observational studies may generate unjustified alarms: The case of medications for nausea and vomiting in pregnancy

OBJECTIVES

Because observational studies often use imperfect measurements, results are prone to misclassification errors. We used as a motivating example the possible teratogenic risks of antiemetic agents in pregnancy since a large observational study recently showed that first-trimester exposure to doxylamine-pyridoxine was associated with significantly increased risk of congenital malformations as a whole, as well as central nervous system defects, and previous observational studies did not show such associations. A meta-analysis on this issue was carried out with the aim to illustrate how differential exposure and outcome misclassifications may lead to uncertain conclusions.

METHODS

Medline, searched to October 2019 for full text papers in English. Summary Odds Ratios (ORs) with confidence intervals (CIs) were calculated using random-effect models. Probabilistic sensitivity analyses were performed for evaluating the extension of differential misclassification required to account for the exposure-outcome association.

RESULTS

Summary ORs were 1.02 (95 % CI, 0.92-1.15), 0.99 (0.82-1.19) and 1.25 (1.08-1.44) for overall congenital, cardiocirculatory, and central nervous system malformations respectively. By assuming exposure and outcome bias factor respectively of 0.95 (i.e., newborns with congenital defects had exposure specificity 5% lower than healthy newborns) and 1.12 (i.e., exposed newborns had outcome sensitivity 12 % higher than unexposed newborns), summary OR of central nervous system defects became 1.13 (95 % CI, 0.99-1.29) and 1.17 (95 % CI, 0.99-1.38).

CONCLUSION

Observational investigations and meta-analyses of observational studies need cautious interpretations. Their susceptibility to several, often sneaky, sources of bias should be carefully evaluated.

Assessing the value of Western Cape Provincial Government health administrative data and electronic pharmacy records in ascertaining medicine use during pregnancy

Background

In African settings, where there is a high disease burden, there is a need to improve the science of documenting and analysing accurate information regarding medicine exposures in women immediately before and during pregnancy to assess the extent of use and safety in pregnant women and their unborn children.

Objectives

To compare evidence of medicine use during pregnancy, as documented in paper-based clinical records (maternity case records (MCRs)) against electronic health information resources (Provincial Health Data Centre (PHDC)) and assess the level of concordance between the two as part of baseline investigations before piloting a provincial pregnancy exposure registry and birth defect surveillance system. The PHDC consolidates electronic clinical and pharmacy data.

Methods

A folder review of completed pregnancies between November 2013 and January 2016 was conducted on randomly selected MCRs from midwife-run obstetric units and a secondary maternity hospital in Cape Town, South Africa. Medication exposures in the MCR were captured and compared with a customised PHDC data extract. The type and timing of drug exposures were compared. Total exposures were compiled from all data sources.

Results

Two hundred and six MCRs from three facilities were sampled: 83 women had documented antiretroviral therapy (ART) exposure; all but 1 (1%) had been recorded in the PHDC extract. There was no evidence of ART use in the MCRs of 4 (5%) cases, despite evidence in the PHDC. There were imprecise drug names in the MCRs of 14 (17%) ART patients, discordant dates of onset between the MCRs and PHDC extracts in 10/83 (12%) and inaccurate medicine names and incorrect dates in 1 (1%) case each. Nine of 10 (90%) women who were administered antituberculosis medication were recorded in the PHDC extract. Ten of 21 (48%) isoniazid preventive therapy treatments appeared in the MCRs and PHDC; 9 (42%) in the PHDC only and 2 (10%) in the MCRs only. Half (n=18/36) of all antibiotic use was reflected only in the MCRs, while 13/36 (36%) appeared only in the PHDC extract. In the former cases, antibiotics used for treatment of sexually transmitted infections and urinary tract infections were dispensed from ward stock and not captured electronically. Antibiotics reflected only in the PHDC were either dispensed at a referral facility or before the first recorded antenatal clinic visit. Folic acid and iron were mostly documented in the MCR only (n=79/99 (80%) and n=107/128 (84%), respectively). However, analgesics and antihistamines more often appeared in the PHDC extract only (n=11/16 (73%) and n=5/5 (100%), respectively).

Conclusions

The PHDC extract provided a better and more complete reflection of chronic drug exposures compared with the MCRs, especially when women sought care at facilities other than the antenatal care unit where they first attended, or when exposures occurred before the initial antenatal visit. The exception was antibiotics dispensed from ward stock to treat sexually transmitted and urinary tract infections.

Risk factors and demographics for microtia in South America: a case-control analysis

BACKGROUND

The etiopathogenesis of microtia is still unknown in the majority of the cases, particularly for individuals presenting with isolated microtia. Our aim was to evaluate potential risk factors for this condition using a case-control approach.

METHODS

We analyzed data from 1,194 live births with isolated microtia enrolled in the ECLAMC study (Estudio Colaborativo Latino Americano de Malformaciones Congénitas) from 1982 to 2011 and their respective controls. Odds ratios (ORs) were estimated with logistic regression models along with 95% confidence intervals for the resulting OR estimates controlling for the effects of potential confounders (sex, maternal age, hospital, and year of birth) for an adjusted OR (aOR).

RESULTS

Multiparity was associated with a higher risk of microtia compared with primiparity (aOR, 1.5; 95% confidence interval [CI], 1.2-1.8), with women who had eight or more prior pregnancies having the highest risk (aOR, 2.8; 95% CI, 1.6-5.2). Women who presented with cold-like symptoms were at higher risk for microtia (aOR, 2.2; 95% CI, 1.2-3.9) as well as those that used tobacco or alcohol during pregnancy (aOR, 1.7; 95% CI, 1.1-2.6 and aOR, 1.4; 95% CI, 0.9-2.1, respectively). The association with alcohol use appeared to be limited to those women who reported binge drinking during pregnancy (aOR, 1.4; 95% CI, 0.7-3.1). Cases from hospitals at low altitude (<2500 m) tended to have more severe types of microtia than those from hospitals at high altitude.

CONCLUSION

These results support the hypothesis that, in addition to teratogens, other nongenetic risk factors contribute to the occurrence of isolated microtia.