RESUMEN
OBJECTIVE: To examine response bias by neuroblastoma screening participation status in a population-based postal survey of parents in Ishikawa Prefecture, Japan. METHODS: The eligibility criteria for the study were: 1) parents whose infants were born in Ishikawa Prefecture between March 1997 and February 1998, and 2) of those parents who resided in the Prefecture in March 1999. Four-page questionnaires were mailed to one-third of screening participants (n = 2,886) and all the nonparticipants (n = 1,401). Questionnaires were anonymous, with no identifiers on the questionnaire. Colored papers were used for printing questionnaires to differentiate screening participation status. Response rates were calculated using demographic information on the infant registry as the denominator and demographic characteristics data from the returned questionnaire as the numerator. RESULTS: The response rate was 63% for participants and 33% for nonparticipants. The following factors were associated with lower response rates regardless of screening participation status: older maternal age (> or = 35 years), higher parity (> or = 4), nuclear family status, and mother having a full-time occupation. Approximately 20% of screening nonparticipants reported having participated in the screening. Place of residence, maternal age, and parity were associated with the percentage of incorrect reporting. CONCLUSION: Screening participation status was a major factor associated with low response rate, although some demographic characteristics were also predictive of low response rates. Incorrect reporting of screening participation among nonparticipants indicates a strong social desirability bias in this official survey in Japan.