The loss of top performers is of growing concern to employers in the Midwest, according to a report by Right Management Inc. A survey of 700 U.S. companies found that 30 percent of respondents expect the defection of top talent to other organizations to be their most pressing human resources challenge in 2011. Another 30 percent said lack of high-potential leaders in their organizations poses the biggest threat. In the Midwest, 30 percent of the 157 companies surveyed view lack of qualified leadership as the biggest concern, and 27 percent worry about losing top performers to other organizations.