Evidence of recall bias in volunteered vs. prompted responses about occupational exposures

Background Recall bias remains a concern in case-control studies, although few investigations have found evidence of differential recall. This study e xamined whether differences in occupational exposure reporting occur in vol unteered vs. prompted questionnaire responses. Methods In. a large, population-based case-control study of a childhood can cer neuroblastoma, Mie calculated odds ratios for broad occupational exposu re groups on the assumption that in the absence of recall bias, risk estima tes for such broad groupings should be close to the null value. Results Prompted exposures and work activities showed little evidence of di fferential recall by parents of cases and controls (all OR < 1.2), bur case parents were more likely to volunteer information about other exposures or activities (ORs: 1.35-1.71), Case mothers were also more likely than contr ol mothers to report activities involving indirect exposure (OR = 1.41), Conclusions These findings suggest that prompted exposure questions a-e les s likely to be subject to recall bias than open-ended questions. (C) 2000 W iley-Liss, Inc.