Such interventions would have the potential to reduce the prevalence of chronic pain in the population .
Although certain risk factors can identify individuals who are most likely to develop chronic pain , few interventions to prevent chronic pain have been identified .
To facilitate the identification of preventive interventions , an IMMPACT meeting was convened to discuss research design considerations for clinical trials investigating the prevention of chronic pain .
We present general design considerations for prevention trials in population s that are at relatively high risk for developing chronic pain .
A vaccine to prevent herpes zoster and postherpetic neuralgia in older adults.
BACKGROUND The incidence and severity of herpes zoster and postherpetic neuralgia increase with age in association with a progressive decline in cell-mediated immunity to varicella-zoster virus ( VZV ) . We tested the hypothesis that vaccination against VZV would decrease the incidence , severity , or both of herpes zoster and postherpetic neuralgia among older adults . METHODS We enrolled 38,546 adults 60 years of age or older in a r and omized , double-blind ,  placebo-controlled trial of an investigational live attenuated Oka/Merck VZV vaccine ( " zoster vaccine " ) . Herpes zoster was diagnosed according to clinical and laboratory criteria . The pain and discomfort associated with herpes zoster were measured repeatedly for six months . The primary end point was the burden of illness due to herpes zoster , a measure affected by the incidence , severity , and duration of the associated pain and discomfort . The secondary end point was the incidence of postherpetic neuralgia . RESULTS More than 95 percent of the subjects continued in the study to its completion , with a median of 3.12 years of surveillance for herpes zoster . A total of 957 confirmed cases of herpes zoster ( 315 among vaccine recipients and 642 among placebo recipients ) and 107 cases of postherpetic neuralgia ( 27 among vaccine recipients and 80 among placebo recipients ) were included in the efficacy analysis . The use of the zoster vaccine reduced the burden of illness due to herpes zoster by 61.1 percent ( P<0.001 ) , reduced the incidence of postherpetic neuralgia by 66.5 percent ( P<0.001 ) , and reduced the incidence of herpes zoster by 51.3 percent ( P<0.001 ) . Reactions at the injection site were more frequent among vaccine recipients but were generally mild . CONCLUSIONS The zoster vaccine markedly reduced morbidity from herpes zoster and postherpetic neuralgia among older adults
Such interventions would have the potential to reduce the prevalence of chronic pain in the population .
Although certain risk factors can identify individuals who are most likely to develop chronic pain , few interventions to prevent chronic pain have been identified .
To facilitate the identification of preventive interventions , an IMMPACT meeting was convened to discuss research design considerations for clinical trials investigating the prevention of chronic pain .
We present general design considerations for prevention trials in population s that are at relatively high risk for developing chronic pain .