Telephone vs. mail survey gives different SF-36 quality-of-life scores among cancer survivors.

OBJECTIVE: To assess whether SF-36 quality-of-life (QOL) subscale scores varied across two survey modes controlling for cancer type and diagnosis cohort. STUDY DESIGN AND SETTING: Stratified random samples of 720 cancer survivors from six cancer types and three time-since diagnosis cohorts were selected from two state cancer registries. Selected survivors were randomly assigned to mail, telephone, or choice of these for survey administration. This study analyzes completed questionnaires obtained from 140 and 155 survivors who were assigned to telephone and mail, respectively. RESULTS: A significant multivariate effect for survey mode was noted. Mean levels for each subscale controlling for age and accounting for cancer type were higher for telephone compared to mail respondents; significant differences were noted for vitality, role physical, and mental health. The impact of cancer type on QOL subscales was not significant, and the effect of mode was consistent across cancer type. CONCLUSIONS: Previous findings in mode effects for the SF-36 are reproduced here among cancer survivors who may feel more comfortable revealing physical and emotional deficits via mail rather than by telephone. For cancer survivors, it may be that "social desirability" favors responses implying more functioning be it perceived, mental, or physical.