An international case-control study on hypospadias. The problem with variability and the beauty of diversity

The maternal drug exposure birth cohort (DEBC) in China

Drug exposure during pregnancy lacks global fetal safety data. The maternal drug exposure birth cohort (DEBC) study, a prospective longitudinal investigation, aims to explore the correlation of maternal drug exposure during pregnancy with pregnancy outcomes, and establish a human biospecimen biobank. Here we describe the process of establishing DEBC and show that the drug exposure rate in the first trimester of pregnant women in DEBC (n = 112,986) is 30.70%. Among the drugs used, dydrogesterone and progesterone have the highest exposure rates, which are 11.97% and 10.82%, respectively. The overall incidence of adverse pregnancy outcomes is 13.49%. Dydrogesterone exposure during the first trimester is correlated with higher incidences of stillbirth, preterm birth, low birth weight, and birth defects, along with a lower incidence of miscarriage/abortion. Due to the limitations of this cohort study, causative conclusions cannot be drawn. Further follow-up and in-depth data analysis are planned for future studies.

EUROmediCAT signal detection: an evaluation of selected congenital anomaly-medication associations

AIMS

To evaluate congenital anomaly (CA)-medication exposure associations produced by the new EUROmediCAT signal detection system and determine which require further investigation.

METHODS

Data from 15 EUROCAT registries (1995-2011) with medication exposures at the chemical substance (5th level of Anatomic Therapeutic Chemical classification) and chemical subgroup (4th level) were analysed using a 50% false detection rate. After excluding antiepileptics, antidiabetics, antiasthmatics and SSRIs/psycholeptics already under investigation, 27 associations were evaluated. If evidence for a signal persisted after data validation, a literature review was conducted for prior evidence of human teratogenicity.

RESULTS

Thirteen out of 27 CA-medication exposure signals, based on 389 exposed cases, passed data validation. There was some prior evidence in the literature to support six signals (gastroschisis and levonorgestrel/ethinylestradiol (OR 4.10, 95% CI 1.70-8.53; congenital heart disease/pulmonary valve stenosis and nucleoside/tide reverse transcriptase inhibitors (OR 5.01, 95% CI 1.99-14.20/OR 28.20, 95% CI 4.63-122.24); complete absence of a limb and pregnen (4) derivatives (OR 6.60, 95% CI 1.70-22.93); hypospadias and pregnadien derivatives (OR 1.40, 95% CI 1.10-1.76); hypospadias and synthetic ovulation stimulants (OR 1.89, 95% CI 1.28-2.70). Antipropulsives produced a signal for syndactyly while the literature revealed a signal for hypospadias. There was no prior evidence to support the remaining six signals involving the ordinary salt combinations, propulsives, bulk-forming laxatives, hydrazinophthalazine derivatives, gonadotropin releasing hormone analogues and selective serotonin agonists.

CONCLUSION

Signals which strengthened prior evidence should be prioritized for further investigation, and independent evidence sought to confirm the remaining signals. Some chance associations are expected and confounding by indication is possible.

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

Background

Different approaches have been used in case-control studies to estimate maternal exposure to medications and the risk of birth defects. However, the performance of these approaches and how they affect the odds ratio (OR) estimates have not been evaluated using birth-defect surveillance programmes. The aim of this study was to evaluate the scope and limitations of three case-control approaches to assess the teratogenic risk of birth defects in mothers exposed to antiepileptic medications, insulin, or acetaminophen.

Methodology/Principal Findings

We studied 110,814 non-malformed newborns and 58,514 live newborns with birth defects registered by the Latin American Collaborative Study of Congenital Anomalies (ECLAMC) between 1967 and 2008. Four controls were randomly selected for each case in the same hospital and period, and three different control groups were used: non-malformed newborns (HEALTHY), malformed newborns (SICK), and a subgroup of SICK, only-exposed cases (OECA). Associations were evaluated using OR and Pearson's chi-square (P<0.01). There were no concordance correlations between the HEALTHY and OECA designs, and the average OR differences ranged from 3.0 to 11.5 for the three evaluated medicines. The overestimations observed for HEALTHY design were increased as higher OR values were given, with a high and statistically significant correlation between the difference and the mean. On the contrary, the concordance correlations obtained between the SICK and OECA designs were quite good, with no significant differences in the average risks.

Conclusions

The HEALTHY design estimates the true population OR, but shows a high rate of false-positive results presumably caused by differential misclassification bias. This bias decreases with the increase of the proportion of exposed controls. SICK and OECA odds ratios cannot be considered a direct estimate of the true population OR except under certain conditions. However, the SICK and OECA designs could provide practical information to generate hypotheses about potential teratogens.

Postmarketing analysis of medicines: methodology and value of the spanish case-control study and surveillance system in preventing birth defects

There are many surveillance systems of congenital defects all over the world; several of them have developed specific approaches to generate and test selected hypotheses regarding human teratogens. However, to the best of our knowledge, none of them have a permanent and systematised programme for the study of the risk and safety of drugs. The aim of this article is to describe the research programme on the potential effects of drugs in pregnancy followed by the Spanish Collaborative Study of Congenital Malformations (ECEMC), which is a permanent ongoing case-control study and surveillance system. The programme to analyse drugs includes a continuous and systematic study on the potential effects of medicines used during pregnancy. This programme has several characteristics that make it different from other current systems: (i) the collection of numerous datapoints (up to 312 per infant) in a case-control design; (ii) the use of a versatile and specific coding of birth defects; (iii) a specific programme for the continuous analysis of the potential effects of each type of drugs used during pregnancy that has been developed specifically for the ECEMC methodology, including its dysmorphological coding system. The description of the ECEMC's approach to surveillance of the effects of drug use during pregnancy may help researches in this area, particularly those using data from birth defects registries.

Assessment of Birth Defects According to Maternal Therapy Among Infants in the Women and Infants Transmission Study

BACKGROUND

To evaluate rate and types of birth defects according to timing of antiretroviral exposure among babies born to HIV-infected women.

METHODS

Anomalies identified during the prenatal, neonatal, or follow-up period were classified using criteria of the Antiretroviral Pregnancy Registry. Antiretroviral use was classified as none, second or third trimester only, or first trimester.

RESULTS

From January 1, 1990 through June 30, 2004, 2527 live births (LBs) occurred to 2353 women. Defects were identified in 90 babies for a rate of 3.56 defects per 100 LBs. The rate of defects was 3.19 per 100 LBs (24 of 752 LBs) with first-trimester antiretroviral exposure, 3.54 per 100 LBs (41 of 1158 LBs) with exposure later in pregnancy, and 4.05 of 100 LBs (25 of 617 LBs) with no antiretroviral use. Only genital abnormalities, specifically hypospadias, were significantly increased among babies born to women with first-trimester exposure to antiretrovirals (7 of 382 male LBs) compared with the 2 other groups (2 of 892 male LBs; P = 0.007). On logistic regression, use of zidovudine in the first trimester was associated with hypospadias (adjusted odds ratio = 10.68, 95% confidence interval: 2.11 to 54.13; P = 0.004).

CONCLUSIONS

In general, data were reassuring, although the frequency of exposure to newer agents was limited. The increased risk of hypospadias after first-trimester exposure must be explored, because this association has not been detected previously.

The potential of the European network of congenital anomaly registers (EUROCAT) for drug safety surveillance: a descriptive study

BACKGROUND

European Surveillance of Congenital Anomalies (EUROCAT) is a network of population-based congenital anomaly registries in Europe surveying more than 1 million births per year, or 25% of the births in the European Union. This paper describes the potential of the EUROCAT collaboration for pharmacoepidemiology and drug safety surveillance.

METHODS

The 34 full members and 6 associate members of the EUROCAT network were sent a questionnaire about their data sources on drug exposure and on drug coding. Available data on drug exposure during the first trimester available in the central EUROCAT database for the years 1996-2000 was summarised for 15 out of 25 responding full members.

RESULTS

Of the 40 registries, 29 returned questionnaires (25 full and 4 associate members). Four of these registries do not collect data on maternal drug use. Of the full members, 15 registries use the EUROCAT drug code, 4 use the international ATC drug code, 3 registries use another coding system and 7 use a combination of these coding systems. Obstetric records are the most frequently used sources of drug information for the registries, followed by interviews with the mother. Only one registry uses pharmacy data. Percentages of cases with drug exposure (excluding vitamins/minerals) varied from 4.4% to 26.0% among different registries. The categories of drugs recorded varied widely between registries.

CONCLUSIONS

Practices vary widely between registries regarding recording drug exposure information. EUROCAT has the potential to be an effective collaborative framework to contribute to post-marketing drug surveillance in relation to teratogenic effects, but work is needed to implement ATC drug coding more widely, and to diversify the sources of information used to determine drug exposure in each registry.

Methodological issues in the epidemiological study of the teratogenicity of drugs

The review presented here discusses and exemplifies problems in epidemiological studies of drug teratogenesis according to methodology: case-control studies, cohort studies, or total population studies. Sources of errors and the possibility of confounding are underlined. The review stresses the caution with which conclusions have to be drawn when exposure data are retrospective or other possible bias exists. It also stresses the problem with the multiple testing situation that is usually present in the studies. It is therefore difficult to draw any firm conclusion from single studies and still more difficult to draw conclusions on causality. As randomized studies are in most cases out of the question, one has to rely on the type of studies which can be made, but the interpretation of the results should be cautious. The ideal study, next to a randomized one, is a large prospective study with detailed exposure information and detailed and unbiased outcome data. Even so, such a study can mainly be used for identifying possible associations which have to be verified or rejected in new studies. Nearly every finding of a risk increase, if not extremely strong, should only be regarded as a tentative signal to be tested in independent studies.

Risk of drug-induced congenital defects

Defects attributable to drug therapy represent about 1% of congenital defects of known aetiology. This means that a precautionary attitude and correct use of drugs in fertile, and especially pregnant, women is a feasible form of prevention. Drugs currently in use with proven teratogenic effect number approximately 25, but new pharmaceutical drugs are constantly in preparation. Recognition of a drug-induced teratogenic effect is a complex procedure taking into account not only experimental animal data but also experience in humans. Considering that 40% of pregnancies are not planned, it follows that any drug with known or suspected teratogenic potential must be used only under strict medical control. Also, adequate knowledge on potential teratogenicity of a drug permits modification of therapy before conception. It goes without saying that any drug should be used during pregnancy only if it is essential, and it would be prudent to use only those where adequate information is provided and prior clinical experience is available. Teratology Information Services can assist both physicians and patients when any doubt exists.