Comparison of three interview methods on response pattern to sensitive and non-sensitive questions

Background: To get more precise responses when gathering information about sensitive topics such as drug use, it is important to use the most optimal method.

Objectives: This study was carried out to address the impact of three interview methods (street-based, household, and telephone interviews) on response pattern to sensitive and non-sensitive questions in terms of participation, disclosure and discontinuing rates.

Patients and methods: We selected three culturally diverse major cities of Iran. Then, we randomly selected 300 subjects, 100 for each type of interview, from each major city (899 in total). For street-based interviews only pedestrians who were walking alone were recruited, for household interviews only one individual from each house participated (3-4 houses in each alley were selected), and for telephone interviews we selected phone numbers using a random number list. We asked five non-sensitive and five sensitive (related to drug use and sexual contact among their personal network) questions.

Results: For telephone and household interviews, relative to street-based interviews, participants were less likely to disclose alcohol and drug-related behaviors (Adjusted OR = 0.76; 95% CI: 0.60- 0.97) and sexual behaviors among their network (Adjusted OR telephone/street-based = 0.64; 95% CI: 0.39- 1.07 and Adjusted OR household/ street-based = 0.56; 95% CI: 0.33- 0.95). We found that participants who were interviewed via the telephone were more likely (Adjusted OR = 1.24) and those who were interviewed at home were less likely (Adjusted OR = 0.86) to report non-sensitive information compared to participants who were interviewed on the street; however, these findings were not statistically significant. The largest participation rate and the least discontinuation rate were observed for household interviews.

Conclusions: It seems that the methods of interview effect response to both sensitive and non-sensitive questions. We believe that for street-based interviews, respondents may disclose more sensitive information than telephone and household interviews.