The term “glaucoma” describes a group of eye conditions with damage to the optic nerve. This is often caused by an abnormally high pressure in the eye. The biological basis of the disease is not yet fully understood. Glaucoma is one of the leading causes of blindness in the world.
Topiramate is licensed to treat a medical condition affecting the brain (epilepsy) and for the prevention of severe headache attacks (migraine).
Recently, medical doctors reported about several patients who developed glaucoma after the use of topiramate. Furthermore, Canadian researchers performed a scientific study similar to this proposed study, and found a slightly increased risk of glaucoma in users of topiramate: topiramate users were 1,5 times more likely to have a glaucoma diagnosis than people in the general population. We therefore aim to assess the association between use of topiramate and the risk of glaucoma with data from UK primary care.
We will include patients with treated glaucoma and control patients with no glaucoma. We will compare previous use of topiramate in the two groups and calculate a relative risk which will tell us the odds of developing glaucoma in users of topiramate compared to non-users.
The results of this study will help patients, clinical practitioners and decision makers in the health care system to judge the risk of glaucoma associated with the use of topiramate.
Previous case reports suggested an association between topiramate and glaucoma. In a case-control study using electronic medical records from British Columbia, researchers found a slightly increased risk of glaucoma after exposure to topiramate compared to unexposed controls. Our aim is to confirm or reject the results of the previous case-control study using a different data source (CPRD Aurum).
We will assess the use of topiramate in adult patients with a recorded incident diagnosis of and treatment for glaucoma (primary open angle glaucoma, primary angle closure glaucoma or unspecified glaucoma). Exposure will be defined as any use of topiramate in the years prior to the index date. We will also evaluate duration of use (i.e., number of prescriptions). We will compare topiramate use among patients with newly diagnosed glaucoma to a matched control sample of the general population without glaucoma or without increased intraocular pressure (>21 mmHg). The comparison group will be matched 1:4 on age, sex, index date (controls will have the same index date as the matched case), general practice, and years of history in the database before the glaucoma diagnosis (or the respective date in the controls). We will exclude patients with secondary or congenital glaucoma, HIV, drug/alcohol abuse, cancer except non-melanoma skin cancer, blindness, or less than three years of medical history on the database before the diagnosis date. We will apply conditional logistic regression to derive odds ratios and 95% confidence intervals. We will adjust our analysis for family history of glaucoma, a diagnosis of diabetes mellitus, use of systemic corticosteroids, and the number of GP visits one year prior to the glaucoma diagnosis.
The results of this study will aid patients, clinical practitioners and decision makers in the health care system to judge the risk of glaucoma associated with the use of topiramate.
Glaucoma (i.e., open angle, angle closure or unspecified)
Susan Jick - Chief Investigator - BCDSP - Boston Collaborative Drug Surveillance Program
- Corresponding Applicant -
Christoph Meier - Collaborator - University of Basel
Luis Velez - Collaborator - University of Basel
Svenja Küng - Collaborator - University of Basel