HIV/AIDS knowledge among men who have sex with men: applying the item response theory

Abstract

OBJECTIVETo 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.METHODSMulticenter, 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.RESULTSOverall, 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.CONCLUSIONSItem 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.

Fatores associados ao baixo conhecimento sobre HIV/AIDS entre homens que fazem sexo com homens no Brasil

“…Torna-se ainda mais preocupante se considerarmos que os itens avaliados abordam informações básicas amplamente divulgadas. A utilização da metodologia TRI permitiu avaliar não somente o grau de conhecimento, mas também os itens considerados mais difíceis e aqueles com a melhor capacidade de discriminação 5,25 .…”

“…As respostas corretas foram categorizadas como "um" e as incorretas e não sabe como "zero". Os escores de conhecimento foram estimados pelo modelo logístico de dois parâmetros (dificuldade e discriminação) fundamentado na Teoria de Resposta ao Item (TRI), cuja metodologia está detalhada no estudo de Gomes et al 5 .…”

“…A definição do ponto de corte da variável resposta ordinal (conhecimento) foi baseada em análise por meio da teoria da resposta ao item publicado anteriormente 5 . Dessa forma, os valores dos percentis 75 e 25 foram considerados para o agrupamento do grau de conhecimento em três categorias (k) de conhecimento: alto (> 75), médio (75-25) e baixo (< 25).…”

“…A prevalência global do HIV foi de 14,2% 3 com variações de 5,2 a 23,7% entre as cidades, e a proporção de relações anais receptivas desprotegidas foi de 36,5% 4 . Da mesma forma, o nível de conhecimento em HIV/AIDS entre os HSH foi avaliado e encontrou-se 40,7% da amostra com níveis de conhecimento abaixo da média 5 .…”

Unprotected receptive anal sex among men who have sex with men, Belo Horizonte, MG

“…Knowledge about HIV transmission was measured by ten questions about HIV transmission and prevention, and subsequently calculated a score by means of Item Response Theory. 15,16 Descriptive analysis of categorical variables and central tendency measures of continuous variables was performed with subsequent categorization. Differences in proportions were evaluated using the chisquared test with significance level of 0.05.…”