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 .
Herpes zoster: risk categories for persistent pain.
Acute neuritis and persistent pain are the most significant clinical manifestations of herpes zoster and are end points for clinical trials therapy . In an acyclovir and prednisone study , patients were categorized according to pain severity and number of lesions at presentation  . Risk categories were defined according to the magnitude of risk ratios ( RRs ) and a comparison of Kaplan-Meier survival estimates . For acute neuritis and zoster-associated pain , RRs defined rate of resolution . Patients who presented with  severe or incapacitating pain  and a large number of lesions were less likely to achieve resolution of both acute neuritis and zoster-associated pain ( RR , 18.0 ; 95 % confidence interval [ CI ] , 6 . 6 - 48.6 , and RR , 5.3 ; 95 % CI , 4.2 - 17.2 , respectively ) . These analyses identify the subgroups of patients for whom aggressive interventions are most strongly indicated
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 .