Validity of Neuropsychological Testing in Young African Children Affected by HIV

Abstract

Introduction: Western-constructed neuropsychological tests have been used in low and middle income countries to assess the impact of HIV/AIDS and other chronic illnesses. We explore using such instruments cross-culturally in a sub-Saharan Africa setting.

Methods: IMPAACT P1104S was a two-year observational study carried out at six clinical sites (South Africa- 3 sites, Malawi, Uganda and Zimbabwe) to assess and compare neuropsychological outcomes in three cohorts of children 5-11 years of age: HIV-infected (HIV), HIV-exposed but uninfected (HEU) and HIV unexposed and uninfected (HU). Descriptive statistics compared socio-demographic characteristics among children at sites. Instruments included the KABC-II cognitive ability, TOVA attention/impulsivity, BOT-2 motor proficiency tests, and BRIEF executive function problems. Test characteristics were assessed using intraclass and Spearman non-parametric correlations, linear regression and principal factor analyses.

Results: Of the 611 participants, 50% were male and mean age ranged from 6.6 to 8 years. In Malawi, Uganda and Zimbabwe, substantial proportions of families lived in rural settings in contrast to the South African sites. Intraclass correlation coefficients between weeks 0 and 48 were highest for the KABC scores, ranging between 0.42 to 0.71.Correlations among similar test domains were low to moderate but significant, with positive correlation between KABC Sequential and TOVA scores and negative correlation between BRIEF and KABC scores. TOVA response time scores correlated negatively with the BOT-2 Total points score. Strong and significant associations between individual measures of growth, disability and development with all test scores were observed. Performance-based measures were markedly lower for HIV compared to HEU and HU participants, even after controlling for age, sex and site. Factor analyses confirmed the underlying theoretical structure of the KABC scaled item scores.

Conclusion: The KABC, TOVA, BRIEF and BOT-2 were valid and reliable tools for assessing the neuropsychological impact of HIV in four sub-Saharan African countries.

Keywords: Africa; Neuropsychological testing; Pediatric HIV; reliability; validity.

Figure 1

The number of participants at each P1104S study visit and reasons for discontinuations. Note: HIV=HIV-infected cohort; HEU=HIV-exposed, uninfected; HU=HIV unexposed, uninfected

Figure 2

Factors and factor loadings for the exploratory factor analysis of scaled KABC items for all study participants. Note: Factor loadings are only shown if 0.40 or over. The values by the curved arrowed lines indicate factor and error variance estimates. Factor variances are scaled to the value “1”. Factor interpretations are noted in the oval shapes; in order of the amount of total variance explained, they are: Learning, Planning (with Simultaneous), Sequential and Simultaneous processing. Values by the straight arrowed lines indicate factor loadings, which represents the correlation of the specific factor with the indicated KABC item. The square of the factor loading indicates the proportion of variance for that item accounted for by the specific factor. For example, the correlation between the factor representing Learning and Rebus is 0.89. The amount of variance of Rebus accounted for by the Learning factor is (.89)²= 79%. Error variances for the item scores indicate the proportion of total variance that is unique and not explained by the four common factors. For example, for Block count, 73% of the total variance is unique to that variable while 27% is common to the four factors (refer to manuscript Table 5 for the communalities).