by Dan Roberts
A relationship has been found, but don’t throw away the meds.
The media has recently been reporting research from the University of Wisconsin, which found an association between development of age-related macular degeneration (AMD) and use of blood pressure (BP) lowering medications. Before patients begin discarding their BP drugs, however, they should realize that an association between a drug and a disease means they have a relationship, not that the drug causes the disease.
Since 1987, the researchers collected data from the National Eye Institute’s Beaver Dam Eye Study on nearly 5,000 people aged 43 to 86 years. They found that vasodilators like Apresoline and Loniten were “associated” with a greater risk of developing early-stage AMD. Specifically, an estimated 8.2% of people not taking BP meds developed signs of early AMD, while 19.1% of people taking the meds developed the disease.
A good amount of research has found a causative relationship between BP and AMD*. It makes sense, therefore, that, since people with high BP are at risk of developing AMD, they are more likely to take vasodilators. This forms a relationship, but not a causative relationship, between the drugs and the disease.
The researchers themselves caution that their study was not able to discern effects of the medications themselves and high BP. Until further research is done to connect the cause to the effect, medications should not be adjusted without advice from a discerning professional.
*Source: Long-term blood pressure and age-related macular degeneration: the ALIENOR study. Cougnard-Grégoire, et al (Invest Ophthalmol Vis Sci. 2013 Mar 28;54(3):1905-12. doi: 10.1167/iovs.12-10192.)