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

Gomes RR, Batista JR, Ceccato Md, Kerr LR, Guimarães MD - Rev Saude Publica (2014)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Secretaria Municipal de Saúde de Belo Horizonte, Belo Horizonte, MG, Brasil.

ABSTRACT

Objective: 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.

Methods: 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.

Results: 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.

Conclusions: 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.

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Related in: MedlinePlus

Graphical representation of the characteristic and information curves of theitems selected.
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f01: Graphical representation of the characteristic and information curves of theitems selected.

Mentions: One item of each type of discrimination is shown in Figure 1, represented on the left by the ICC and on the right by thecurve of the item information. As observed, the ICC of item 5 is the steepest curve,gently sloping to the right of the knowledge scale. This indicates that a slightincrease in the level of knowledge is capable of significantly increasing theprobability of a correct response to this item. Because item 5 had the highestdegree of discrimination, it is capable of distinguishing individual knowledge atmuch closer levels, as compared to the remaining items. On the other hand, ICC foritem 1 is almost a straight line parallel to the scale of knowledge, indicating thatan increase in the theta values does not significantly change the probability ofcorrectly answering the item, i.e., low discriminatory power of this item. The iteminformation curve shows how much the item contributes to the measure of knowledge,i.e., it indicates precisely which levels of theta were better discriminated.Usually the item brings best information about a few theta levels than others, andits representation resembles a normal curve type. The information curve of item 5brought more information for measuring the levels of knowledge around value 3.0.Outside this amplitude, the item starts producing incorrect information on the levelof knowledge, since the standard error curve is inversely proportional to theinformation curve. On the other hand, the information curve of item 1 showed thatthis item hardly contributed with any information for measuring HIV/AIDSknowledge.


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

Gomes RR, Batista JR, Ceccato Md, Kerr LR, Guimarães MD - Rev Saude Publica (2014)

Graphical representation of the characteristic and information curves of theitems selected.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4206150&req=5

f01: Graphical representation of the characteristic and information curves of theitems selected.
Mentions: One item of each type of discrimination is shown in Figure 1, represented on the left by the ICC and on the right by thecurve of the item information. As observed, the ICC of item 5 is the steepest curve,gently sloping to the right of the knowledge scale. This indicates that a slightincrease in the level of knowledge is capable of significantly increasing theprobability of a correct response to this item. Because item 5 had the highestdegree of discrimination, it is capable of distinguishing individual knowledge atmuch closer levels, as compared to the remaining items. On the other hand, ICC foritem 1 is almost a straight line parallel to the scale of knowledge, indicating thatan increase in the theta values does not significantly change the probability ofcorrectly answering the item, i.e., low discriminatory power of this item. The iteminformation curve shows how much the item contributes to the measure of knowledge,i.e., it indicates precisely which levels of theta were better discriminated.Usually the item brings best information about a few theta levels than others, andits representation resembles a normal curve type. The information curve of item 5brought more information for measuring the levels of knowledge around value 3.0.Outside this amplitude, the item starts producing incorrect information on the levelof knowledge, since the standard error curve is inversely proportional to theinformation curve. On the other hand, the information curve of item 1 showed thatthis item hardly contributed with any information for measuring HIV/AIDSknowledge.

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Secretaria Municipal de Saúde de Belo Horizonte, Belo Horizonte, MG, Brasil.

ABSTRACT

Objective: 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.

Methods: 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.

Results: 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.

Conclusions: 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.

Show MeSH
Related in: MedlinePlus