@article{ref1,
title="Is the use of oral contraceptives associated with operatively treated anterior cruciate ligament injury? A case-control study from the Danish Knee Ligament Reconstruction Registry",
journal="American journal of sports medicine",
year="2014",
author="Rahr-Wagner, Lene and Thillemann, Theis Muncholm and Mehnert, Frank and Pedersen, Alma Becic and Lind, Martin",
volume="42",
number="12",
pages="2897-2905",
abstract="BACKGROUND: The incidence of anterior cruciate ligament (ACL) injuries is 2 to 9 times higher in women than in men. In addition, in vitro studies have demonstrated that ACL is an estrogen target tissue, and some studies have therefore suggested a protective association between oral contraceptives (OC) and the likelihood of sustaining ACL injury. HYPOTHESIS: There is a protective association between OC use and the likelihood of operatively treated ACL injury. STUDY DESIGN: Case-control study; Level of evidence, 3. <br><br>METHODS: The study population included 4497 women with an operatively treated ACL injury registered in the Danish Knee Ligament Reconstruction Registry for the 2005 to 2011 period and 8858 age-matched controls with no ACL injury. The study evaluated exposure to OC use at the time of ACL injury (index date) and in the 5 previous years (&quot;ever user&quot;) or no OC use (&quot;never user&quot;). Ever users were further classified as either new users (patients who redeemed their first prescription within the first year before the index date), long-term users (redeemed additional prescriptions 1 to 5 years before the index date), or recent users (redeemed their most recent prescription >1 year before the index date). Finally, a dose-response analysis of OC use was performed. Conditional logistic regression was used to calculate the relative risk (RR) with a 95% CI of sustaining an operatively treated ACL injury according to OC use. <br><br>RESULTS: The adjusted RR associating OC with ACL injury was 0.82 (95% CI, 0.75-0.90) between ever users and never users. Furthermore, there was a decreased RR of sustaining ACL injury of 0.80 (95% CI, 0.74-0.91) in long-term users and 0.81 (95% CI, 0.72-0.89) in recent users. Using OC for more than 4 years did not seem to alter the likelihood of sustaining an operatively treated ACL injury. <br><br>CONCLUSION: This population-based pharmacoepidemiological study including 13,355 women indicates that a protective association exists between OC use and the likelihood of sustaining an operatively treated ACL injury. Although this study does indicate a protective association of OC use, OC should not be used as a prophylactic measure before additional clinical studies have further clarified the biological and causal association between OC use and the likelihood of sustaining operatively treated ACL injury.<p /> <p>Language: en</p>",
language="en",
issn="0363-5465",
doi="10.1177/0363546514557240",
url="http://dx.doi.org/10.1177/0363546514557240"
}