Objective: MASTER, a multicenter prospective study, was conducted to provide a thorough understanding of the burden of herpes zoster (HZ) and postherpetic neuralgia (PHN). Objectives are to: (1) describe the herpes zoster severity-of-illness (HZSOI), a composite measure of pain duration and severity; and (2) to identify the characteristics at recruitment predictive of greater HZSOI at the different phases of HZ.
Methods: From October, 2005 to July, 2006, 261 outpatients with HZ, aged more than equal to 50 years, were recruited within 14 days of rash onset across Canada. The pain was measured by the Zoster Brief Pain Inventory at recruitment and 7, 14, 21, 30, 60, 90, 120, 150, and 180 days later. The HZSOI represents the area under the curve of pain severity over time and ranges from 0 (no pain) to 1800 (pain=10 for 180 d).
Results: Median pain duration was 32.5 days. The predictors of greater HZSOI varied according to the different phases of HZ. Higher pain severity at recruitment, more lesions, lower income, and being immunocompromised were the predictors of a greater acute HZSOI. Higher acute pain severity, lower income, being immunocompromised, older age, and not receiving antivirals were the predictors of greater postherpetic HZSOI.
Discussion: Using an informative measure capturing simultaneously the burden caused by pain duration and severity, we identified subgroups that suffer most during the different phases of HZ. It is interesting to note that, younger participants were as likely to suffer as the older ones during the acute phase of HZ. This information should aid in optimizing the treatment and prevention of HZ.