Evaluation of Three Postal Invitational Strategies to Increase Survey Response Rates in a Combat-Injured U.S. Military Population: Findings From the Wounded Warrior Recovery Project.

The survival rate of those injured in combat in overseas contingency operations is higher than in previous conflicts. There is a need to assess the long-term psychosocial and quality of life outcomes of those injured in combat, yet surveying this population presents inherent challenges. As part of a large-scale, longitudinal examination of patient-reported outcomes of service members injured on deployment, the present manuscript evaluated the effectiveness of three postal strategies on response rates: (1) mailing a study prenotification postcard, (2) mailing the survey invitation in a larger envelope, and (3) including a small cash preincentive ($2). Evaluation of these strategies yielded mixed results in this population. Neither the prenotification postcard nor inclusion of a $2 cash preincentive significantly increased response rates. However, use of a larger envelope to mail the survey invitation significantly increased the response rate by 53.1%. Researchers interested in collecting patient-reported outcomes among military populations, including those with combat-related injuries, may find that increasing the visibility of recruitment materials is more effective for improving response rates than attempting to cognitively prime or offer prospective participants preincentives.