shcri.com - Postherpetic neuralgia (PHN) is the most common complication of herpes zoster infection, and is the result of the reactivation of the varicella-zoster virus acquired during the primary varicella infection (chickenpox). PHN is one of the main causes of neuropathic pain in herpes zoster patients ages 60 years and older (Stankus et al., 2000). The main symptom of PHN is severe pain and allodynia (pain resulting from a non-injurious stimulus to the skin). The pain associated with PHN is often described as a deep aching, burning, stabbing sensation, or a feeling similar to an electric shock; this pain, which can last for months, is sensitive to touch and/or temperature changes. PHN is associated with a significant loss of activity levels and a reduced quality of life, particularly in the elderly, due to the intermittent or constant frequency of the accompanying pain symptoms (Dubinsky et al., 2004; Stankus et al., 2000). -EpiCast Report: Postherpetic Neuralgia - Epidemiology Forecast to 2022
PHN with pain persisting for three or more months after the onset of a herpes zoster rash is relatively common and affects approximately 9-34% of herpes zoster patients in the US, depending on the population studied. The incidence of PHN varies widely in Europe, from 2.6% of herpes zoster patients developing PHN in the Netherlands, to 32.1% of herpes zoster patients developing PHN in France (Dworkin and Portenoy, 1996; Johnson and McElhaney, 2009; Mick et al., 2010; Opstelten et al., 2002). Since there is no single treatment for PHN, treatment is customized for each patient. Currently, there is no absolute preventative therapy for PHN. However, a vaccine is available to help prevent herpes zoster infection; in turn, this vaccine helps reduce the incidence of PHN to an extent because PHN is the sequela of herpes zoster (Chen et al., 2011).
EpiCast Report: Postherpetic Neuralgia - Epidemiology Forecast to 2022 provides an overview of the risk factors and the global and historical trends for PHN in the 7MM. In addition, this report includes a 10-year epidemiological forecast (2012-2022) of the diagnosed incident cases of PHN (defined as pain persistent for three or more months after herpes zoster rash onset) segmented by age (ages 50-85+ years) and sex in these markets.
EpiCast Report: Postherpetic Neuralgia - Epidemiology Forecast to 2022 forecasts that the diagnosed incident cases of PHN in the seven major markets (7MM) (US, France, Germany, Italy, Spain, UK, and Japan) will grow by 20.22% over the next decade, from 241,808 cases in 2012 to 290,694 cases in 2022, with over 50% of the incident cases occurring in the US and France combined. The increase in the number of incident cases of PHN in the 7MM can be attributed to changing population demographics in the respective markets, rather than to an actual forecast increase in the incidence of PHN.
The definitions of PHN vary among studies because there is no universal definition for the disease. EpiCast Report: Postherpetic Neuralgia - Epidemiology Forecast to 2022 only selected studies that defined PHN as pain persistent for three or more months after the onset of a herpes zoster rash. Therefore, studies defining PHN as pain persistent for one or more months, or pain persistent for six or more months were excluded to keep the incidence measures consistent across the 7MM. Furthermore, EpiCast Report: Postherpetic Neuralgia - Epidemiology Forecast to 2022 excluded studies that were not representative of the entire population, as well as studies conducted prior to the introduction of herpes zoster vaccination programs in a country, because they may not reflect the most recent PHN incidence rates.