Poor contraceptive practices are leading to pregnancies in users of isotretinoin, a drug that causes birth defects
In a Canadian study involving four provinces, researchers found that female patients with acne who are prescribed isotretinoin (trade names include Accutane, Clarus and Epuris), a drug known to harm the fetus, are becoming pregnant during therapy. These findings were observed despite clear Canadian guidelines for prescribers and patients designed to prevent pregnancy occurring during, and for at least one month after, treatment.
Published in the latest issue of the Canadian Medical Association Journal (CMAJ), the research was conducted by the Canadian Network for Observational Drug Effect Studies (CNODES), part of the Drug Safety and Effectiveness Network (DSEN). The research was requested by Health Canada, who required information about the rate of pregnancy among women using isotretinoin in Canada. This information is often under-reported.
Isotretinoin is a widely-used and effective treatment for severe acne. It is also a known teratogen, which can cause serious birth defects, involving the face, head, heart and brain, in children exposed during pregnancy.
CNODES researchers from four provinces (British Columbia, Saskatchewan, Manitoba and Ontario) examined anonymous health records of more than 59,000 patients in Canada. The researchers found evidence suggesting that between four and six out of every 1,000 patients may have become pregnant during treatment. The at-risk period for exposure extends beyond the end of treatment and higher pregnancy rates were recorded when follow-up was extended to determine final pregnancy outcomes. Pregnancy rates during isotretinoin treatment remained relatively stable over the 15 – year study period (1996 – 2011), indicating there has been no improvement in pregnancy prevention.
The pregnancy prevention program in Canada requires informed written consent by the patient, as well as two negative pregnancy tests before starting isotretinoin, and two reliable forms of contraception during treatment and one month after. Despite these recommendations, researchers found prescription data showing that less than one-third of isotretinoin users were prescribed an oral contraceptive, a rate similar to that observed in the year before they started isotretinoin. Other forms of contraception could not be assessed and the researchers noted that they were not able to track the use of birth control pills obtained without plan coverage, perhaps from a free clinic, directly from a supply maintained by their doctor, or the use of IUDs or barrier methods.
Another area of poor adherence with prescribing advice concerned the need to reserve isotretinoin for the most severe cases and try less restricted and safer treatments for acne before graduating to isotretinoin. In this study between 45 per cent and 72 per cent of isotretinoin users had been prescribed other acne treatments in the year prior, with the lowest rate in the Ontario cohort. This observation and the low use of oral contraceptives point to clear areas for improvement in the management of acne and isotretinoin therapy.
“Our findings reinforce the importance of ensuring patients and health professionals, including physicians and pharmacists, are fully aware of the vital importance of avoiding pregnancy while taking isotretinoin, and that this drug should be considered for females only when other safer options have failed,” said lead author David Henry, senior scientist, Institute for Clinical Evaluative Sciences (ICES) and professor at the Dalla Lana School of Public Health at the University of Toronto. “Adherence to the guidelines is essential, but is not happening consistently in Canada.”
Based on the study findings, the large majority of these potentially exposed pregnancies were lost spontaneously by miscarriage (20 per cent) or through medically-induced termination of pregnancy (70 per cent). In total, 118 children were born after being exposed to isotretinoin during pregnancy, of whom 11 had malformations. Further information on these abnormalities could not be obtained.
“Although the likelihood of becoming pregnant while using isotretinoin is low with good adherence to the Canadian guidelines, when it happens, the consequences can be profound,” advised co-author Dr. Brandace Winquist, research consultant to the Saskatchewan Health Quality Council. “Because of the potential risk to their baby’s health, women becoming pregnant while using this medication may feel medical termination of pregnancy is their only option.”
The CNODES network has a mandate to analyze large amounts of anonymous patient data in Canadian provinces to assess questions of drug safety more reliably than would otherwise be possible in smaller trials or epidemiological studies.
“This study from the CNODES team demonstrates the importance of pan-Canadian collaboration in addressing questions of prescription drug safety,” said Dr. Samy Suissa, the principal investigator of CNODES and director of the Centre for Clinical Epidemiology at the Lady Davis Institute at the Jewish General Hospital in Montreal. “The cutting-edge approach and the ability to study large numbers of patients anonymously provide more efficient and effective protection of the health of Canadians.”
"Occurrence of pregnancy and pregnancy outcomes during isotretinoin therapy" was published today in the Canadian Medical Association Journal (CMAJ).
Citation: Henry D, Dormuth CR, Winquist B, Carney G, Bugden S, Teare GF, Levesque L, Berard A, Paterson JM, Platt RW and the Canadian Network for Observational Drug Effect Studies (CNODES)*
CNODES is part of the Drug Safety and Effectiveness Network (DSEN), which is funded by Health Canada, and the Canadian Institutes of Health Research (CIHR). For more about CNODES: www.cnodes.ca
The Institute for Clinical Evaluative Sciences (ICES) is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of health care issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting health care needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy. For the latest ICES news, follow us on Twitter: @ICESOntario
*CNODES Investigators: Samy Suissa (Principal Investigator, McGill University); David Henry and Michael Paterson (Ontario); Colin Dormuth (British Columbia); Brenda Hemmelgarn (Alberta); Gary Teare (Saskatchewan); Patricia Caetano (Manitoba); Pierre Ernst, Jacques LeLorier, and Robert Platt (Québec); and Adrian Levy and Ingrid Sketris (Nova Scotia).
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