Clinical Health Updates

Moderate-severe pain unusual following zoster

Clinical Question:
What is the natural history of pain following herpes zoster?

Bottom Line:
In a longitudinal observational study of 94 patients (39 M:55 F, mean age 69) at elevated risk for developing post herpetic neuralgia (PHN), the natural history of pain during the first 6 months after herpes zoster (HZ) rash onset was determined. Pain severity and impact were rated using pain-VAS, SF-MPQ, and MPI. Applying a definition of PHN of average daily pain >0/100 on the pain VAS during the last 48 h, 30 subjects had PHN at 6 months. These 30 subjects reported more pain and a higher SF-MPQ score (p<0.01)> or = 30/100 on the pain VAS). Defining PHN as average daily pain >0/100 at 6 months after rash onset appears to substantially overestimate the number of HZ patients negatively impacted by ongoing pain and disability.

Reference:
Thyregod HG, Rowbotham MC, Peters M, Possehn J, Berro M, Petersen KL. Natural history of pain following herpes zoster. Pain 2007;128:148-156.

Study Design:
Cohort (retrospective)

Synopsis:
The likelihood and severity of PHN has not been well-described in the medical literature, and definitions vary as to what it actually is. To evaluate the natural history of PHN, these investigators enrolled 94 immunocompetent subjects who all completed the 6-month study. All had herpes zoster on the neck or trunk producing pain of at least 20 on a 0 to 100-mm visual analog scale (VAS). The patients were recruited through newspaper advertisements, physician referrals, and community outreach programs in San Francisco. The majority of patients received antiviral treatment. Using a definition of pain as a any score greater than 0 on the VAS, 50% of patients had pain at 3 months and 32% still reported pain at 6 months. The average pain score at 6 months was 11. However, “clinically relevant pain,” defined as a score greater than 30 mm on the VAS, was present in only 3% of patients at 3 months and only 2% of patients at 6 months. Patients with pain were more likely to have zoster in the cervical and lumbar regions.