Time-tradeoff Values and Standard-gamble Utilities Assessed during Telephone Interviews versus Face-to-face Interviews

The purpose of this study was to compare time-tradeoff values and standard-gamble utilities obtained during telephone interviews with those obtained through face-to-face interviews. Sixty-five patients with peripheral arterial occlusive disease completed both interviews. One week prior to the telephone interview, the patients received by mail a questionnaire in which the value and utility measures were presented in writing. The face-to-face interviews used the same questions, but the interviewer used visual aids. The mean time-tradeoff values were 0.84 (SD 0.20) vs 0.86 (SD 0.17) for the telephone and face-to-face interviews, respectively (p = 0.31). The mean standard-gamble utilities were 0.93 (SD 0.16) vs 0.92 (SD 0.17) for the telephone and face-to-face interviews, respectively (p = 0.26). In conclusion, telephone interviews yield similar time-tradeoff values and standard-gamble utilities compared with face-to-face interviews, suggesting that telephone interviews can replace face-to-face interviews. Key works: utility as sessment ; time tradeoff; standard gamble; telephone interviews. (Med Decis Making 1998;18:400-405)