A Pharmacoepidemiologic Approach to Evaluate Real-world Effectiveness of Hormonal Contraceptives in the Presence of Drug-drug Interactions

Prenatal Care Initiation and Exposure to Teratogenic Medications

Importance

With new legal abortion restrictions, timing of prenatal care initiation is critical to allow for discussion of reproductive options among pregnancies exposed to teratogenic medications.

Objective

To investigate the prevalence of prenatal exposure to teratogenic medications and prenatal care initiation across gestational weeks.

Design, Setting, and Participants

This descriptive, population-based cross-sectional study used health encounter data from a national sample of individuals with employer-sponsored health insurance. A validated algorithm identified pregnancies among persons identifying as female that ended with a live or nonlive outcome between January 2017 and December 2019. Data were analyzed from December 2022 to December 2023.

Exposures

Prenatal exposure to any of 137 teratogenic medications, measured via pharmacy and medical claims. Measurement of prenatal care initiation was adapted from the Children's Health Care Quality Measures.

Main Outcomes and Measures

Prevalence of prenatal exposure to teratogens and prenatal care initiation by gestational week. Timing of prenatal teratogenic exposure was compared with timing of prenatal care initiation and legal abortion cutoffs.

Results

Among 639 994 pregnancies, 472 472 (73.8%; 95% CI, 73.7%-73.9%) had a live delivery (mean [SD] age, 30.9 [5.4] years) and 167 522 (26.2%; 95% CI, 26.1%-26.3%) had a nonlive outcome (mean [SD] age, 31.6 [6.4] years). Of pregnancies with live deliveries, 5.8% (95% CI, 5.7%-5.8%) were exposed to teratogenic medications compared with 3.1% (95% CI, 3.0%-3.2%) with nonlive outcomes. Median time to prenatal care was 56 days (IQR, 44-70 days). By 6 weeks' gestation, 8186 pregnancies had been exposed to teratogenic medications (25.2% [95% CI, 24.7%-25.7%] of pregnancies exposed at any time during gestation; 1.3% [95% CI, 1.3%-1.3%] of all pregnancies); in 6877 (84.0%; 95% CI, 83.2%-84.8%), prenatal care was initiated after 6 weeks or not at all. By 15 weeks, teratogenic exposures had occurred for 48.9% (95% CI, 48.4%-49.5%) of all teratogen-exposed pregnancies (2.5% [2.4-2.5] of all pregnancies); prenatal care initiation occurred after 15 weeks for 1810 (16.8%; 95% CI, 16.1%-17.5%) with live deliveries and 2975 (58.3%; 95% CI, 56.9%-59.6%) with nonlive outcomes. Teratogenic medications most used within the first 15 gestational weeks among live deliveries included antiinfectives (eg, fluconazole), anticonvulsants (eg, valproate), antihypertensives (eg, lisinopril), and immunomodulators (eg, mycophenolate). For nonlive deliveries, most antihypertensives were replaced by vitamin A derivatives.

Conclusions and Relevance

In this cross-sectional study, most exposures to teratogenic medications occurred in early pregnancy and before prenatal care initiation, precluding prenatal risk-benefit assessments. Prenatal care commonly occurred after strict legal abortion cutoffs, prohibiting consideration of pregnancy termination if concerns about teratogenic effects arose.

Common teratogenic medication exposures-a population-based study of pregnancies in the United States

BACKGROUND

Risk mitigation for most teratogenic medications relies on risk communication via drug label, and prenatal exposures remain common. Information on the types of and risk factors for prenatal exposures to medications with teratogenic risk can guide strategies to reduce exposure.

OBJECTIVE

This study aimed to identify medications with known or potential teratogenic risk commonly used during pregnancy among privately insured persons.

STUDY DESIGN

We used the Merative™ MarketScan® Commercial Database to identify pregnancies with live or nonlive (ectopic pregnancies, spontaneous and elective abortions, stillbirths) outcomes among persons aged 12 to 55 years from 2011 to 2018. Start/end dates of medication exposure and pregnancy outcomes were identified via an adapted algorithm based on validation studies. We required continuous health plan enrollment from 90 days before conception until 30 days after the pregnancy end date. Medications with known or potential teratogenic risk were selected from TERIS (Teratogen Information System) and drug monographs based on the level of risk and quality of evidence (138 with known and 60 with potential risk). We defined prenatal exposure on the basis of ≥1 outpatient pharmacy claim or medical encounter for medication administration during target pregnancy periods considering medication risk profiles (eg, risk only in the first trimester or at a certain dose threshold). Sex hormones and hormone analogs, and abortion and postpartum/abortion hemorrhage treatments were not considered as teratogenic medications because of challenges in separating pregnancy-related indications, nor were opioids (because of complex risk-benefit considerations) or antiobesity medications if their only teratogenic mechanism was weight loss.

RESULTS

Among all pregnancies, the 10 medications with known teratogenic risk and the highest prenatal exposures were sulfamethoxazole/trimethoprim (1988 per 100,000 pregnancy-years), high-dose fluconazole (1248), topiramate (351), lisinopril (144), warfarin (57), losartan (56), carbamazepine (50), valproate (49), vedolizumab (28 since 2015), and valsartan (25). Prevalence of exposure to sulfamethoxazole/trimethoprim decreased from 2346 to 1453 per 100,000 pregnancy-years from 2011 to 2018, but prevalence of exposure to vedolizumab increased 6-fold since its approval in 2015. Prenatal exposures in the first trimester were higher among nonlive pregnancies than among live-birth pregnancies, with the largest difference observed for warfarin (nonlive 370 vs live birth 78), followed by valproate (258 vs 86) and topiramate (1728 vs 674). Prenatal exposures to medications with potential teratogenic risk were most prevalent for low-dose fluconazole (6495), metoprolol (1325), and atenolol (448). The largest first-trimester exposure differences between nonlive and live-birth pregnancies were observed for lithium (242 vs 89), gabapentin (1639 vs 653), and duloxetine (1914 vs 860). Steady increases in hydralazine and gabapentin exposures were observed during the study years, whereas atenolol exposure decreased (561 to 280).

CONCLUSION

Several medications with teratogenic risk for which there are potentially safer alternatives continue to be used during pregnancy. The fluctuating rates of prenatal exposure observed for select teratogenic medications suggest that regular reevaluation of risk mitigation strategies is needed. Future research focusing on understanding the clinical context of medication use is necessary to develop effective strategies for reducing exposures to medications with teratogenic risk during pregnancy.

Improved survival of non-small cell lung cancer patients after introducing patient navigation: A retrospective cohort study with propensity score weighted historic control

OnkoNetwork is a patient navigation program established in the Moritz Kaposi General Hospital to improve the timeliness and completeness of cancer investigations and treatment. The H2020 SELFIE consortium selected OnkoNetwork as a promising integrated care initiative in Hungary and conducted a multicriteria decision analysis based on health, patient experience, and cost outcomes. In this paper, a more detailed analysis of clinical impacts is provided in the largest subgroup, non-small cell lung cancer (NSCLC) patients. A retrospective cohort study was conducted, enrolling new cancer suspect patients with subsequently confirmed NSCLC in two annual periods, before and after OnkoNetwork implementation (control and intervention cohorts, respectively). To control for selection bias and confounding, baseline balance was improved via propensity score weighting. Overall survival was analyzed in univariate and multivariate weighted Cox regression models and the effect was further characterized in a counterfactual analysis. Our analysis included 123 intervention and 173 control NSCLC patients from early to advanced stage, with significant between-cohort baseline differences. The propensity score-based weighting resulted in good baseline balance. A large survival benefit was observed in the intervention cohort, and intervention was an independent predictor of longer survival in a multivariate analysis when all baseline characteristics were included (HR = 0.63, p = 0.039). When post-baseline variables were included in the model, belonging to the intervention cohort was not an independent predictor of survival, but the survival benefit was explained by slightly better stage distribution and ECOG status at treatment initiation, together with trends for broader use of PET-CT and higher resectability rate. In conclusion, patient navigation is a valuable tool to improve cancer outcomes by facilitating more timely and complete cancer diagnostics. Contradictory evidence in the literature may be explained by common sources of bias, including the wait-time paradox and adjustment to intermediate outcomes.

Development of a Translational Exposure-Bracketing Approach to Streamline the Development of Hormonal Contraceptive Drug Products

Worldwide, 922 million women of reproductive age (or their partners) use some sort of contraception to prevent pregnancy. Oral combined hormonal contraceptives (CHC) typically utilize a combination of a progestin and an estrogen. CHC are potentially at risk to metabolic drug-drug interaction (DDI) via CYP3A4, the main enzyme involved in the oxidative metabolism of ethinyl estradiol (EE) and most progestins, e.g. levonorgestrel (LNG) and drospirenone (DRSP). Recently, the FDA issued a guidance addressing metabolic DDIs in the realm of CHC, establishing an overall class-based recommendation with respect to avoidance of CYP3A4 induction interactions. Given that different progestins have varying magnitudes of fraction metabolized by CYP3A4 (fm_CYP3A4 ), it would be of clinical benefit to determine if all progestins are at the same risk to CYP3A4-mediated metabolic DDI. LNG and DRSP are commonly used progestins that are at the margins of the rifampicin induction effect observed in vivo since they have the relatively lowest and highest fm_CYP3A4 among commonly used CHC formulations containing norgestimate, desogestrel, norgestrel, and norethindrone. Therefore, we applied a multi-pronged strategy, i.e. (1) development of the PBPK models, (2) comparison of the effect of CYP3A inducers and inhibitors on DRSP vs. LNG, and (3) providing the clinical-practice context based on real world data, to explore the difference in DDI risk for oral CHCs.

Application of exposure bracketing to streamline the development of contraceptive products

Developing new long-acting products of well-characterized contraceptive drugs is one way to address some of the reasons for unmet need for modern methods of family planning among women in low- and middle-income countries. Development and approval of such products traditionally follow a conventional paradigm that includes large Phase 3 clinical trials to evaluate efficacy (pregnancy prevention) and safety of the investigational product. Exposure-bracketing is a concept that applies known pharmacokinetics and pharmacodynamics of a drug substance to inform its safe and efficacious use in humans. Several therapeutic areas have applied this concept by leveraging established drug concentration-response relationships for approved products to expedite development and shorten the timeline for the approval of an investigational product containing the same drug substance. Based on discussions at a workshop hosted by the Bill & Melinda Gates Foundation in December 2020, it appears feasible to apply exposure-bracketing to develop novel contraceptive products using well-characterized drugs.

Antiseizure medications and oral contraceptives: Impact of enzyme inducers on pregnancy outcomes and costs

PURPOSE

To show the impact of drug-drug interactions (DDIs) associated with co-administration of enzyme-inducing (EI) antiseizure medications and oral contraceptives (OCs) on the annual number of unintended pregnancies, their outcomes, and their associated costs in the United States (US).

METHODS

A Microsoft Excel pregnancy-outcomes model was developed to determine the impact of DDIs in women who take an OC as well as an EI antiseizure medication known to lower the effectiveness of the OC in preventing pregnancy. The model compared the number of unintended pregnancies, the expected pregnancy outcomes, and associated costs in women taking an OC and an EI medication with a matched cohort of women who took an OC and an enzyme-neutral (EN) antiseizure medication that is known not to interact with OCs. The model perspectives were patients and third-party payers in the US. Unintended pregnancy rates, pregnancy outcomes, and cost inputs for the model were taken from published studies.

RESULTS

The results of the analysis showed an estimated increase in the annual number of unintended pregnancies in the US of 503 (a change from 1151 to 1654), an increase of 44.7%, for the estimated 71,922 women currently taking an OC plus an EI medication in the US when compared with a matched cohort taking an OC plus an EN medication. This resulted in an estimated annual healthcare cost increase of $3 million, which is an increase of 5.5% in the annual costs for contraception and pregnancy care. A scenario analysis showed that the annual number of unintended pregnancies could be lower (575 vs 1654) for a matched cohort of women taking EI medications and using a copper intrauterine device, a highly effective and nonhormonal form of contraception, rather than an OC.

CONCLUSIONS

Physicians treating women of reproductive age for epilepsy who wish to avoid pregnancy should consider the potential for DDIs that might result in unintended pregnancies. Thus, physicians should alert women using EI medications for epilepsy control to the increased potential for unintended pregnancies if they use OCs for contraception.

Quantifying the economic burden of unintended pregnancies due to drug–drug interactions with hormonal contraceptives from the United States payer perspective

Background: In the United States of America (USA), nearly 10 million women use oral contraceptives (OCs). Concomitant administration of certain medications can result in contraceptive failure, and consequently unintended pregnancies due to drug–drug interactions (DDIs). The objective of this analysis was to estimate the economic impact of unintended pregnancies due to DDIs among women of reproductive age using an OC alone or in combination with an enzyme inducer co-medication in the USA from a payer perspective. Methods: A Markov model using a cohort of 1,000 reproductive-age women was developed to estimate costs due to contraceptive failure for OC alone versus OC with concomitant enzyme inducer drugs. All women were assumed to begin an initial state, continuing until experiencing an unintended pregnancy. Unintended pregnancies could result in birth, induced abortion, spontaneous abortion, or ectopic pregnancy. The cohort was analyzed over a time horizon of 1 year with a cycle length of 1 month. Estimates of costs and probabilities of unintended pregnancy outcomes were obtained from the literature. Probabilities from the Markov cohort trace was used to estimate number of pregnancy outcomes. Results: On average, enzyme inducers resulted in 20 additional unintended pregnancies with additional unadjusted and adjusted costs median (range) of USD136,304 (USD57,436–USD320,093) and USD65,146 (USD28,491–USD162,635), respectively. The major component of the direct cost is attributed to the cost of births. Considering the full range of events, DDIs with enzyme inducers could result in 16–25 additional unintended pregnancies and total unadjusted and adjusted costs ranging between USD46,041 to USD399,121 and USD22,839 to USD202,788 respectively. Conclusion: The direct costs associated with unintended pregnancies due to DDIs may be substantial and are potentially avoidable. Greater awareness of DDI risk with oral contraceptives among payers, physicians, pharmacists and patients may reduce unintended pregnancies in at-risk populations.