O'Connor EE, et al. – This study was performed to evaluate the consistency across studies of HIV effects on DTI measures and then examine the DTI reliability in a longitudinal seropositive cohort. Findings revealed substantial variations regarding HIV effects on WM microstructure that could result from acquisition, processing, or cohort–selection differences. On carefully controlling acquisition parameters and processing, the resulting DTI measures did not show high temporal variation. HIV effects on WM microstructure could be age–dependent. The high longitudinal reliability of DTI WM microstructure measures suggested them promising disease–activity markers.

Methods

• Data sources included published studies and investigators.
• 16 cross–sectional studies reporting fractional anisotropy and 12 studies reporting mean diffusivity in the corpus callosum were included in this meta–analysis .
• Researchers used random–effects meta–analysis to estimate study standardized mean differences and heterogeneity.
• Estimation of DTI longitudinal reliability was performed in seropositive participants studied before and 3 and 6 months after beginning treatment.

Results

• Findings revealed that seropositive participants had lower fractional anisotropy (standardized mean difference, -0.43; P < .001) and higher mean diffusivity (standardized mean difference, 0.44; P < .003).
• Nevertheless, between–study heterogeneity accounted for 58% and 66% of the observed variance (P < .01).
• In contrast, researchers observed higher longitudinal cohort fractional anisotropy and lower mean diffusivity in seropositive participants (both, P < .001), and fractional anisotropy and mean diffusivity measures were very stable during 6 months, with intraclass correlation coefficients all >0.96.