Non oral contraceptives carry higher clot risks

Copenhagen, May 11 (IANS) Certain non-oral hormonal contraceptives, skin patches, implants and vaginal rings carry a higher risk of serious blood clots than others, says a new study.

Several studies have assessed the risk of venous thrombosis (blood clots) in women using oral contraceptive pills, but now studies have assessed the risk in users of non-oral hormonal contraceptives. These products more continuously release hormones into the body to prevent pregnancy.

A team, led by Ojvind lidegaard professor at the University of Copenhagen, reviewed data on non-oral hormonal contraceptive use and first ever venous thrombosis in all Danish non-pregnant women aged between 15 and 49 years from 2001 to 2010. All the women had no record of either blood clots or cancer before the study began.

Several factors that could affect the results, including age and education level, were taken into account. The results are based on 9,429,128 observation years during which 3,434 confirmed diagnoses of first ever venous thrombosis were recorded, the British Medical Journal reports.

The risk of clots among women who did not use any type of hormonal contraception and who were 15-49 years old was on average two events per 10,000 exposure years. Women taking a combined oral contraceptive pill containing the hormone levonorgestrel had a three times increased risk, according to a Copenhagen statement.

Compared with non-users of the same age, women who used a skin patch had an eight times increased risk, while women who used a vaginal ring had a 6.5 times increased risk.

Unlike combined pills, no reduction in risk was seen with long-term use of a patch or a vaginal ring. Based on these findings, the authors calculated that 2,000 women using a vaginal ring and 1,250 women using a skin patch should shift to a combined pill containing levonorgestrel to prevent one event of venous thrombosis in one year.