Does Crosswise Method Cause Overestimation? An Example to Estimate the Frequency of Symptoms Associated With Sexually Transmitted Infections in General Population: A Cross Sectional Study

Abstract

Background: Crosswise, as an indirect questioning method, is not applied to the general population. The current study aimed at assessing the feasibility of crosswise among Iranian general population to estimate the frequency of sexually transmitted infection (STI) symptoms. Methods: To estimate the frequency of STI-associated symptoms among the general population of Kerman, Iran, in 2014, participants were inquired to specify whether their "yes or no" answers to a set of paired questions (sensitive/non-sensitive) were the same (concordance) or different (discordance). Based on the frequency of concordance response and known prevalence of positive response to non-sensitive questions, the frequency of positive responses to the sensitive questions was estimated. The estimations were compared with the results of a population-based survey, conducted at the same time and setting, in which participants directly responded to the sensitive questions. Results: The current study recruited 128 people aged 18 - 60 years (50 male). The estimated frequency for genital ulcer in crosswise method was 53.1 and 34.9 in males and females, respectively. The estimated frequency of urethral discharge in crosswise method was 72.3. The crosswise method outcomes were significantly different from those of the survey (P > 0.05). Conclusions: The estimated frequency of STI-associated symptoms in crosswise was unexpectedly higher than that of obtained by the population-based survey. Hence, experts in the field of STIs did not accept the crosswise estimations. This overestimation could be a result of differences in the ability of people, with various socioeconomic levels, to understand conceptually how to answer the questions along with the influence of study setting and administration method of questionnaires on the participants self-reports.