Gomes Raquel Regina de Freitas Magalhães, Batista José Rodrigues, Ceccato Maria das Graças Braga, Kerr Lígia Regina Franco Sansigolo, Guimarães Mark Drew Crosland
Secretaria Municipal de Saúde de Belo Horizonte, Belo Horizonte, MG, Brasil.
Faculdade de Educação, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil.
Rev Saude Publica. 2014 Apr;48(2):206-15. doi: 10.1590/s0034-8910.2014048004911.
To evaluate the level of HIV/AIDS knowledge among men who have sex with men in Brazil using the latent trait model estimated by Item Response Theory.
Multicenter, cross-sectional study, carried out in ten Brazilian cities between 2008 and 2009. Adult men who have sex with men were recruited (n = 3,746) through Respondent Driven Sampling. HIV/AIDS knowledge was ascertained through ten statements by face-to-face interview and latent scores were obtained through two-parameter logistic modeling (difficulty and discrimination) using Item Response Theory. Differential item functioning was used to examine each item characteristic curve by age and schooling.
Overall, the HIV/AIDS knowledge scores using Item Response Theory did not exceed 6.0 (scale 0-10), with mean and median values of 5.0 (SD = 0.9) and 5.3, respectively, with 40.7% of the sample with knowledge levels below the average. Some beliefs still exist in this population regarding the transmission of the virus by insect bites, by using public restrooms, and by sharing utensils during meals. With regard to the difficulty and discrimination parameters, eight items were located below the mean of the scale and were considered very easy, and four items presented very low discrimination parameter (< 0.34). The absence of difficult items contributed to the inaccuracy of the measurement of knowledge among those with median level and above.
Item Response Theory analysis, which focuses on the individual properties of each item, allows measures to be obtained that do not vary or depend on the questionnaire, which provides better ascertainment and accuracy of knowledge scores. Valid and reliable scales are essential for monitoring HIV/AIDS knowledge among the men who have sex with men population over time and in different geographic regions, and this psychometric model brings this advantage.
运用项目反应理论估计的潜在特质模型，评估巴西男男性行为者的艾滋病毒/艾滋病知识水平。
2008年至2009年在巴西十个城市开展多中心横断面研究。通过应答驱动抽样招募成年男男性行为者（n = 3746）。通过面对面访谈的十条陈述确定艾滋病毒/艾滋病知识，并运用项目反应理论通过双参数逻辑模型（难度和区分度）获得潜在分数。使用项目功能差异分析按年龄和受教育程度检查每个项目特征曲线。
总体而言，运用项目反应理论得出的艾滋病毒/艾滋病知识得分未超过6.0（范围0 - 10），均值和中位数分别为5.0（标准差 = 0.9）和5.3，40.7%的样本知识水平低于平均水平。该人群中仍存在一些关于病毒通过蚊虫叮咬、使用公共卫生间和用餐时共用器具传播的观念。关于难度和区分度参数，八个项目位于量表均值以下，被认为非常容易，四个项目的区分度参数非常低（< 0.34）。缺乏难度较大的项目导致对中等水平及以上人群知识测量不准确。
聚焦每个项目个体属性的项目反应理论分析，能够获得不随问卷变化或依赖问卷的测量结果，从而提高知识得分的确定度和准确性。有效且可靠的量表对于长期监测不同地理区域男男性行为者人群的艾滋病毒/艾滋病知识至关重要，这种心理测量模型具有这一优势。
