Natural history of pain following herpes zoster

Abstract

In a longitudinal observational study of 94 patients (39M:55F, 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 hours, 30 subjects had PHN at 6 months. These 30 subjects reported more pain and a higher SF-MPQ score (p<0.01) at study inclusion than the 64 subjects whose pain completely resolved by 6 months. At 6 months, mean daily pain in the PHN group was 11/100 (95% CI 5,16) and only nine of these subjects were still taking prescription medication for HZ pain. The rate of recovery (pain severity over time) was the same in the PHN and no-pain groups. At study inclusion, the SF-MPQ and MPI scores in our PHN group were similar to historical controls with chronic severe PHN enrolled in clinical trials, but by 6 months the scores in our PHN subjects were significantly lower than historic controls. Only two subjects met the more stringent criteria for 'clinically meaningful' PHN at 6 months (≥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.

Postherpetic Neuralgia #272

“…1 For those who develop PHN, prolonged severe disabling symptoms rarely remain beyond six months. 5 A small subset may experience irreversible damage to skin and sensory abnormalities that can result in ongoing pain for years. 2 For all patients with acute HZ and/or PHN, physical and emotional quality of life can be affected.…”

Zoster-Associated Pain and Post Herpetic Neuralgia

“…More recently this definition has been revised, with a further distinction (Arani et al, www.intechopen.com 2001; Jung et al, 2004, Niv & Maltsman-Tseikhin, 2005: pain present within 30 days from the onset of rash is defined as acute herpetic neuralgia; pain present between 30 and 120 days is defined as subacute herpetic neuralgia; pain persisting after 120 days from the onset of HZ is defined as PHN. Moreover other authors introduced the concept that only clinically relevant pain should be defined as PHN, to avoid overestimation of the problem: they proposed PHN to be defined as pain ≥3 on a 10-point VAS scale persisting 120 days after rash healing (Coplan et al, 2004;Oxman et a., 2005;Thyregod et al, 2007). All these definitions, however, introduce purely arbitrary partitions of an entity that is a continuum, from prodromal to post herpetic pain.…”

“…The prospective Italian study already quoted had a very similar approach, using verbal rating pain scores instead of worst pain scores in the calculation of AUC (Parruti et al, 2010). A recent study ) used a slightly different measure (HZ severity of illness, HZSOI) in which scores below 3 on a 0-to-10 scale were considered as zero, as they have been demonstrated not to affect relevantly quality of life and activities of daily living (Thyregod et al, 2007). The predictive role of HZSOI for greater acute and post herpetic pain burden was assessed in 261 HZ patients enrolled within 14 days of rash onset, strictly followed with different pain questionnaires up to 6 months .…”

“…Verbal rating scales, asking to the patient to define his pain as no pain, mild, moderate, intense or very intense, are easy to handle in real clinical life, but don't allow to stratify and better characterize pain. Visual Analogue Scales (VAS) have been extensively investigated and used in various settings of pain clinical management (Hao et al, 1994;Thyregod et al, 2007), allowing a more precise identification of the single patient's pain level, and being easily understood by patients. Other structured tools have been defined in recent years: McGill Pain Questionnaire and its Short Form (Melzack 2005) are widely used for pain evaluation in a consistent part of more recent studies (Melzack & Togerson, 1971;Thyregod et al, 2007;Ursini et al, 2010) as they allow to evaluate different pain dimensions (sensory, affective and mixed features).…”

“…Visual Analogue Scales (VAS) have been extensively investigated and used in various settings of pain clinical management (Hao et al, 1994;Thyregod et al, 2007), allowing a more precise identification of the single patient's pain level, and being easily understood by patients. Other structured tools have been defined in recent years: McGill Pain Questionnaire and its Short Form (Melzack 2005) are widely used for pain evaluation in a consistent part of more recent studies (Melzack & Togerson, 1971;Thyregod et al, 2007;Ursini et al, 2010) as they allow to evaluate different pain dimensions (sensory, affective and mixed features). Zoster Brief Pain Inventory (ZBPI) is the more specific tool designed on-purpose for HZ pain (Coplan et al, 2004): it includes discomfort other than pain, such as itch, occurring in the same area as HZ rash.…”