May 10, 2004 -- A set of indicators may help doctors predict which people will suffer prolonged pain after a bout of shingles, according to a new study.
Shingles is an infection caused by the varicella-zoster virus, the virus that causes chickenpox. It is one of the most common neurological diseases and affects about half a million Americans each year. The condition causes a rash that appears as a band on one side of the body and moderate to severe pain that usually lasts three to five weeks. Shingles is triggered by a reactivation of the virus that has been dormant in someone who has had chickenpox.
In about a quarter of shingles cases, the pain persists for more than four months after the rash develops. This condition is known as postherpetic neuralgia, or PHN.
Until now, older age was the only known risk factor linked to PHN among people with shingles.
But this study, published in the May 11 issue of Neurology, suggests that several other factors may also affect the risk of developing PHN and may help doctors identify which patients would need preventive treatments.
Post-Shingles Pain Predictors
In the study, researchers examined data from 965 shingles patients who participated in two separate clinical trials of an antiviral drug.
Researchers found several criteria emerged as significant risk factors for PHN:
- Older age
Presence of symptoms before the rash appeared
Severe pain during initial stages of the illness
Larger extent of rash
The results suggest that these risk factors may reflect different mechanisms that each contribute to the development of chronic post-shingles pain.
"In future research, it will be important to examine whether additional risk factors, such as sensory thresholds or psychological distress, and various methods of weighting risk factors can increase the accuracy of this prediction," write researcher Beth F. Jung, EdD, MD, MPH, of the University of Rochester School of Medicine and Dentistry, and colleagues.