Postherpetic Neuralgia Incidence Following Shingles
Approximately 10-30% of patients who develop shingles will develop postherpetic neuralgia (PHN), with the percentage varying significantly by age and time point measured.
Age-Stratified Risk
The incidence of PHN increases dramatically with age:
- Patients over 50 years: 40% develop PHN 1
- Patients over 75 years: 75% develop PHN, with the proportion among HZ cases aged >75 years being 4% 2, 1
- General adult population: Approximately 20% of all shingles patients develop PHN 3
Time-Based Prevalence
The percentage of patients with persistent pain decreases over time after the acute shingles episode:
PHN is formally defined as pain persisting or recurring at the site of shingles at least 3 months (120 days) after the onset of the acute rash 5, 1.
Critical Risk Factors Beyond Age
Several factors significantly increase the likelihood of developing PHN:
- Severity of acute pain: More severe pain during the acute shingles episode strongly predicts PHN development 4, 1
- Prodromal pain: Pain before rash onset increases risk 1
- Rash extent: Spread beyond a single dermatome, particularly affecting the face or trigeminal distribution 5, 1
- Viremia at presentation: Detection of viral DNA in blood at presentation is significantly associated with pain persisting at 6 months or beyond 4
Clinical Impact
PHN accounts for 11-15% of all referrals to pain clinics and represents the most common and debilitating complication of herpes zoster, particularly in the elderly 2, 5. Patients with PHN demonstrate higher consumption of healthcare services, including outpatient visits, emergency room visits, and hospital admissions 2.
Prevention Context
The most effective strategy to prevent PHN is vaccination against herpes zoster. The recombinant zoster vaccine (RZV/Shingrix) demonstrates 88.8% efficacy against PHN in adults ≥70 years, while the live zoster vaccine (ZVL/Zostavax) shows 66.5% efficacy 2. Early antiviral treatment of acute shingles and pre-emptive treatment with low-dose tricyclics (10-25 mg nightly) from the time of diagnosis can reduce PHN incidence by approximately 50% 5.