Non-response was related to younger age, less education, higher BSI-12 and OASIS scores at 6 months; younger age, higher BSI-12, Sheehan Disability and OASIS scores, higher rate of panic, and higher rate among Hispanics at 12 months; and younger age, higher BSI-12 and OASIS scores, lower preference for current health state, higher rate of panic, and higher rate among Hispanics at 18 months.