Allergy tests useful before implanting devices

NEW YORK (Reuters Health) - Patients with an allergy to metal, often first revealed when wearing certain jewelry, are also at risk for reactions to implanted medical devices made of metal, such as pacemakers and orthopedic prostheses.

Patch testing, which involves placing some of the suspected allergen on the skin, can be helpful in detecting medical device reactions. However, doctors need to wait longer than usual when looking to see if a skin reaction has occurred, researchers report in the Archives of Dermatology.

Normally, researcher Dr. Mark D. P. Davis told Reuters Health, readings at days 3 and 5 "are adequate for detecting contact allergy to most of the common allergens." In the case of metal allergy, however, the reaction may be delayed and doctors should look again at days 7 to 10.

In the present study, Davis, from the Mayo Clinic in Rochester, Minnesota, and colleagues reviewed the results of 44 patients who were tested for metal allergies and found that testing before the device was implanted helped identify those with allergies. In four out of five patients, detection of the allergy led to a change in the device used.

SOURCE: Archives of Dermatology, August 2008.