Phillip Chan

Dr. Phillip Chan

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Research Focus & Metrics

Academic Career Length

15Years (2012-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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7 January 2020 in AIDS Research and Therapy
Verified
Journal Article
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PCPhillip Chan
Phillip Chan
OGOrlanda Goh
Orlanda Goh
EKEugène Kroon
Eugène Kroon
DCDonn Colby
Donn Colby
CSCarlo Sacdalan
Carlo Sacdalan
RPRobert Paul
Robert Paul
Introduction: Dolutegravir (DTG)-based antiretroviral therapy (ART) is currently the first-line treatment for people living with HIV. Neuropsychiatric adverse events (NP-AEs) have been reported with DTG but neuropsychiatric symptoms have not been systemically quantified using structured scales. This study examined mood and cognitive parameters before and after a planned transition from non-DTG to DTG-based ART within a longitudinal study of acute HIV infection (AHI). Methods: RV254 AHI cohort participants on ≥ 24 weeks of ART initiated at AHI underwent sequential assessments before and after the switch including: (1) Patient Health Questionnaire-9 (PHQ-9), a 9-item survey (scores 0–27) that evaluates somatic and affective/cognitive symptoms of depression; (2) a 2-Questions screening that has been validated locally for depression; (3) Distress Thermometer (scores 0–10); and 4) administration of a 4-test neurocognitive battery sensitive to HIV. Results: 254 individuals (95% male, median age 30) switched to a DTG-based regimen after a median 144 weeks of ART. Serial assessments were completed at a median of 19 weeks before and 37 weeks after DTG. There was a modest but statistically significant increase in PHQ-9 scores after DTG (pre-switch: 5 [IQR 1–7] vs. Post-switch: 5 [IQR 2–8], p = 0.009). The percentage of participants with at least moderate depression (PHQ-9 ≥ 10) increased from 10 to 16% (p = 0.006), but the frequency of moderate-severe depression (PHQ-9 ≥ 15) remained unchanged (3%). No volunteer reported NP-AEs within the study period. Somatic symptoms of depression increased more than cognitive/affective symptoms. Plasma viral suppression (HIV-1 RNA < 50; p = 0.005) and PHQ-9 ≥ 10 (p < 0.001) before switch were linked to lower PHQ-9 scores after DTG in multivariable analysis. Performance on all neuropsychological tests, except grooved pegboard test, improved modestly after DTG (all p < 0.05). Conclusion: After a median duration of 37 weeks of DTG use, there was a modest increase in the higher quartile of PHQ-9. This increase was associated with a rise in moderate depression symptoms but not the more severe forms of depression on PHQ-9. No clinically relevant NP-AEs were reported. Pre-existing depression was not associated with subsequent worsening of symptoms after DTG. Cognitive test performance improved post-DTG but could be due to practice effect.

10 April 2017 in European Journal of Clinical Microbiology & Infectious Diseases
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HEHakan Erdem
Hakan Erdem
AIA. Inan
A. Inan
EGE. Guven
E. Guven
SHSally Hargreaves
Sally Hargreaves
LLLykke Larsen
Lykke Larsen
MNM. Nassar
M. Nassar


19 June 2014 in Current Neurology and Neuroscience Reports
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BBBruce J. Brew
Bruce J. Brew
PCPhillip Chan
Phillip Chan

1 January 2018 in NeuroImage: Clinical
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Journal Article
Open access
VSVishal Samboju
Vishal Samboju
CPCarissa L. Philippi
Carissa L. Philippi
PCPhillip Chan
Phillip Chan
YCYann Cobigo
Yann Cobigo
JFJames L.K. Fletcher
James L.K. Fletcher
VVVictor Valcour
Victor Valcour
HIV RNA is identified in cerebrospinal fluid (CSF) within eight days of estimated viral exposure. Neurological findings and impaired neuropsychological testing performance are documented in a subset of individuals with acute HIV infection (AHI). The purpose of this study was to determine whether microstructural white matter and resting-state functional connectivity (rsFC) are disrupted in AHI. We examined 49 AHI (100% male; mean age = 30 ± SD 9.9) and 23 HIV-uninfected Thai participants (78% male; age = 30 ± 5.5) with diffusion tensor imaging (DTI) and rsFC acquired at 3 Tesla, and four neuropsychological tests (summarized as NPZ-4). MRI for the AHI group was performed prior to combination antiretroviral treatment (ART) in 26 participants and on average two days (range:1-5) after ART in 23 participants. Fractional anisotropy (FA), mean (MD), axial (AD), and radial diffusivity (RD) were quantified for DTI. Seed-based voxelwise rsFC analyses were completed for the default mode (DMN), fronto-parietal, and salience and 6 subcortical networks. rsFC and DTI analyses were corrected for family-wise error, with voxelwise comparisons completed using t-tests. Group-specific voxelwise regressions were conducted to examine relationships between imaging indices, HIV disease variables, and treatment status. The AHI group had a mean (SD) CD4 count of 421(234) cells/mm3 plasma HIV RNA of 6.07(1.1) log10 copies/mL and estimated duration of infection of 20(5.5) days. Differences between AHI and CO groups did not meet statistical significance for DTI metrics. Within the AHI group, voxelwise analyses revealed associations between brief exposure to ART and higher FA and lower RD and MD bilaterally in the corpus callosum, corona radiata, and superior longitudinal fasciculus (p < 0.05). Diffusion indices were unrelated to clinical variables or NPZ-4. The AHI group had reduced rsFC between left parahippocampal cortex (PHC) of the DMN and left middle frontal gyrus compared to CO (p < 0.002). Within AHI, ART status was unrelated to rsFC. However, higher CD4 cell count associated with increased rsFC for the right lateral parietal and PHC seeds in the DMN. Direct associations were noted between NPZ-4 correspond to higher rsFC of the bilateral caudate seed (p < 0.002). Study findings reveal minimal disruption to structural and functional brain integrity in the earliest stages of HIV. Longitudinal studies are needed to determine if treatment with ART initiated in AHI is sufficient to prevent the evolution of brain dysfunction identified in chronically infected individuals.

17 May 2016 in Current HIV/AIDS Reports
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Journal Article
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PCPhillip Chan
Phillip Chan
JHJoanna Hellmuth
Joanna Hellmuth
SSSerena Spudich
Serena Spudich
VVVictor Valcour
Victor Valcour