Philip Tarr

Dr. Philip Tarr

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Research Focus & Metrics

Academic Career Length

21Years (2006-Present)

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

Representative Publications

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1 June 2021 in Annals of Internal Medicine
Verified
Journal Article
Closed access
BSBernard Surial
Bernard Surial
CMCatrina Mugglin
Catrina Mugglin
ACAlexandra Calmy
Alexandra Calmy
MCMatthias Cavassini
Matthias Cavassini
HGHuldrych Günthard
Huldrych Günthard
ARAndri Rauch
Andri Rauch
This study compared changes in body weight, lipid levels, and development of obesity over 18 months among patients with HIV who switched from tenofovir disoproxil fumarate to tenofovir alafenamide ... Visual Metabolic Changes After Replacing TDF With TAF. This study compared changes in body weight, lipid levels, and development of obesity over 18 months among patients with HIV who switc... Background: Tenofovir-based antiretroviral therapy (ART) has become first-line in all major HIV treatment guidelines. Compared with tenofovir disoproxil fumarate (TDF), tenofovir alafenamide (TAF) ...

3 May 2023 in The Lancet Healthy Longevity
Verified
Journal Article
Open access
ISIsabella C Schoepf
Isabella C Schoepf
AEAndrés Esteban-Cantos
Andrés Esteban-Cantos
CTChristian W Thorball
Christian W Thorball
BRBerta Rodés
Berta Rodés
PRPeter Reiss
Peter Reiss
PTPhilip Tarr
Philip Tarr
Accelerated epigenetic ageing can occur in untreated HIV infection and is partially reversible with effective antiretroviral therapy (ART). We aimed to make a long-term comparison of epigenetic ageing dynamics in people with HIV during untreated HIV infection and during suppressive ART. In this longitudinal study, conducted over 17 years in HIV outpatient clinics in Switzerland, we applied 5 established epigenetic age estimators (epigenetic clocks) in peripheral blood mononuclear cells (PBMCs) in Swiss HIV Cohort Study participants before or during suppressive ART. All participants had a longitudinal set of PBMC samples available at four timepoints (T1-T4). T1 and T2 had to be 3 years or longer apart, as did T3 and T4. We assessed epigenetic age acceleration (EAA) and a novel rate of epigenetic ageing. Between March 13, 1990, and Jan 18, 2018, we recruited 81 people with HIV from the Swiss HIV Cohort Study. We excluded one participant because a sample did not meet quality checks (transmission error). 52 (65%) of 80 patients were men, 76 (95%) were white, and the median patient age was 43 (IQR 37·5-47) years. Per year of untreated HIV infection (median observation 8·08 years, IQR 4·83-11·09), mean EAA was 0·47 years (95% CI 0·37 to 0·57) for Horvath's clock, 0·43 years (0·3 to 0·57) for Hannum's clock, 0·36 years (0·27 to 0·44) for SkinBlood clock, and 0·69 years (0·51 to 0·86) for PhenoAge. Per year of suppressive ART (median observation 9·8 years, IQR 7·2-11), mean EAA was -0·35 years (95% CI -0·44 to -0·27) for Horvath's clock, -0·39 years (-0·50 to -0·27) for Hannum's clock, -0·26 years (-0·33 to -0·18) for SkinBlood clock, and -0·49 years (-0·64 to -0·35) for PhenoAge. Our findings indicate that people with HIV epigenetically aged by a mean of 1·47 years for Horvath's clock, 1·43 years for Hannum's clock, 1·36 years for SkinBlood clock, and 1·69 years for PhenoAge per year of untreated HIV infection; and 0·65 years for Horvath's clock, 0·61 years for Hannum's clock, 0·74 years for SkinBlood clock, and 0·51 years for PhenoAge, per year of suppressive ART. GrimAge showed some change in the mean EAA during untreated HIV infection (0·10 years, 0·02 to 0·19) and suppressive ART (-0·05 years, -0·12 to 0·02). We obtained very similar results using the rate of epigenetic ageing. Contribution of multiple HIV-related, antiretroviral, and immunological variables, and of a DNA methylation-associated polygenic risk score to EAA was small. In a longitudinal study over more than 17 years, epigenetic ageing accelerated during untreated HIV infection and decelerated during suppressive ART, highlighting the importance of limiting the duration of untreated HIV infection. Swiss HIV Cohort Study, Swiss National Science Foundation, and Gilead Sciences.

1 July 2014 in Open Forum Infectious Diseases
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Journal Article
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BHBarbara Hasse
Barbara Hasse
MIMartin Iff
Martin Iff
BLBruno Ledergerber
Bruno Ledergerber
ACAlexandra Calmy
Alexandra Calmy
PSPatrick Schmid
Patrick Schmid
SYS. Yerly
S. Yerly
Background. The factors that contribute to increasing obesity rates in human immunodeficiency virus (HIV)-positive persons and to body mass index (BMI) increase that typically occurs after starting antiretroviral therapy (ART) are incompletely characterized. Methods. We describe BMI trends in the entire Swiss HIV Cohort Study (SHCS) population and investigate the effects of demographics, HIV-related factors, and ART on BMI change in participants with data available before and 4 years after first starting ART. Results. In the SHCS, overweight/obesity prevalence increased from 13% in 1990 (n = 1641) to 38% in 2012 (n = 8150). In the participants starting ART (n = 1601), mean BMI increase was 0.92 kg/m2 per year (95% confidence interval, .83–1.0) during year 0–1 and 0.31 kg/m2 per year (0.29–0.34) during years 1–4. In multivariable analyses, annualized BMI change during year 0–1 was associated with older age (0.15 [0.06–0.24] kg/m2) and CD4 nadir 350 (P < .001). Annualized BMI change during years 1–4 was associated with CD4 nadir 350 (P = .001) and black compared to white ethnicity (0.28 [0.16–0.37] kg/m2). Individual ART combinations differed little in their contribution to BMI change. Conclusions. Increasing obesity rates in the SHCS over time occurred at the same time as aging of the SHCS population, demographic changes, earlier ART start, and increasingly widespread ART coverage. Body mass index increase after ART start was typically biphasic, the BMI increase in year 0–1 being as large as the increase in years 1–4 combined. The effect of ART regimen on BMI change was limited.

26 March 2013 in Clinical Infectious Diseases
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Journal Article
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MRMargalida Rotger
Margalida Rotger
TGTracy R. Glass
Tracy R. Glass
TJThomas Junier
Thomas Junier
JLJens Lundgren
Jens Lundgren
JNJames D. Neaton
James D. Neaton
TSthe Swiss HIV Cohort Study
the Swiss HIV Cohort Study
Background Persons infected with human immunodeficiency virus (HIV) have increased rates of coronary artery disease (CAD). The relative contribution of genetic background, HIV-related factors, antiretroviral medications, and traditional risk factors to CAD has not been fully evaluated in the setting of HIV infection. Methods In the general population, 23 common single-nucleotide polymorphisms (SNPs) were shown to be associated with CAD through genome-wide association analysis. Using the Metabochip, we genotyped 1875 HIV-positive, white individuals enrolled in 24 HIV observational studies, including 571 participants with a first CAD event during the 9-year study period and 1304 controls matched on sex and cohort. Results A genetic risk score built from 23 CAD-associated SNPs contributed significantly to CAD (P = 2.9×10−4). In the final multivariable model, participants with an unfavorable genetic background (top genetic score quartile) had a CAD odds ratio (OR) of 1.47 (95% confidence interval [CI], 1.05–2.04). This effect was similar to hypertension (OR = 1.36; 95% CI, 1.06–1.73), hypercholesterolemia (OR = 1.51; 95% CI, 1.16–1.96), diabetes (OR = 1.66; 95% CI, 1.10–2.49), ≥1 year lopinavir exposure (OR = 1.36; 95% CI, 1.06–1.73), and current abacavir treatment (OR = 1.56; 95% CI, 1.17–2.07). The effect of the genetic risk score was additive to the effect of nongenetic CAD risk factors, and did not change after adjustment for family history of CAD. Conclusions In the setting of HIV infection, the effect of an unfavorable genetic background was similar to traditional CAD risk factors and certain adverse antiretroviral exposures. Genetic testing may provide prognostic information complementary to family history of CAD.

24 March 2018 in European Heart Journal
Verified
Journal Article
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PTPhilip Tarr
Philip Tarr
BLBruno Ledergerber
Bruno Ledergerber
ACAlexandra Calmy
Alexandra Calmy
TDThanh Doco-Lecompte
Thanh Doco-Lecompte
AMAlex Marzel
Alex Marzel
SSSwiss HIV Cohort Study
Swiss HIV Cohort Study
HIV-positive persons have increased cardiovascular event rates but data on the prevalence of subclinical atherosclerosis compared with HIV-negative persons are not uniform. We assessed subclinical atherosclerosis utilizing coronary artery calcium (CAC) scoring and coronary computed tomography angiography (CCTA) in 428 HIV-positive participants of the Swiss HIV Cohort Study and 276 HIV-negative controls concurrently referred for clinically indicated CCTA. We assessed the association of HIV infection, cardiovascular risk profile, and HIV-related factors with subclinical atherosclerosis in univariable and multivariable analyses. HIV-positive participants (median duration of HIV infection, 15 years) were younger than HIV-negative participants (median age 52 vs. 56 years; P < 0.01) but had similar median 10-year Framingham risk scores (9.0% vs. 9.7%; P = 0.40). The prevalence of CAC score >0 (53% vs. 56.2%; P = 0.42) and median CAC scores (47 vs. 47; P = 0.80) were similar, as was the prevalence of any, non-calcified/mixed, and high-risk plaque. In multivariable adjusted analysis, HIV-positive participants had a lower prevalence of calcified plaque than HIV-negative participants [36.9% vs. 48.6%, P < 0.01; adjusted odds ratio (aOR) 0.57; 95% confidence interval (CI) 0.40–0.82; P < 0.01], lower coronary segment severity score (aOR 0.72; 95% CI 0.53–0.99; P = 0.04), and lower segment involvement score (aOR 0.71, 95% CI 0.52–0.97; P = 0.03). Advanced immunosuppression was associated with non-calcified/mixed plaque (aOR 1.97; 95% CI 1.09–3.56; P = 0.02). HIV-positive persons in Switzerland had a similar degree of non-calcified/mixed plaque and high-risk plaque, and may have less calcified coronary plaque, and lower coronary atherosclerosis involvement and severity scores than HIV-negative persons with similar Framingham risk scores.

31 January 2022 in BMJ Open
Verified
Journal Article
Open access
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CSCorina L Schwendener
Corina L Schwendener
LKLaura M Kiener
Laura M Kiener
KJKristen Jafflin
Kristen Jafflin
SRSarah Rouached
Sarah Rouached
AJAnna Juillerat
Anna Juillerat
PTPhilip Tarr
Philip Tarr
Objectives We aimed to provide a detailed characterisation of human papillomavirus (HPV) vaccine awareness, knowledge and information sources in the HPV vaccine decision-making process of youth, both male and female, in Switzerland. Design With a mixed-method study design, we conducted quantitative questionnaires and qualitative interviews, which lasted 20–45 min. Setting and participants We recruited participants, 15–26 years of age, in physicians’ offices, in a local sexual health clinic, and during military enlistment. We administered quantitative questionnaires to 997 youth participants (585 male, 412 female) and conducted qualitative interviews with 31 youth (17 male, 14 female). Primary and secondary outcome measures We assessed HPV vaccine awareness, knowledge, information sources and vaccination status. Results In the study’s quantitative component, 108 (20%) male and 262 (65%) female participants had received ≥1 dose of HPV vaccine. 697 (70%) participants were knowledgeable about the HPV vaccine. Females were more likely to be knowledgeable than males (342/412 (83%) vs 355/585 (61%); p<0.01). Younger participants in the sample compared with older participants were more likely to be aware of HPV vaccine (135/148 (91%) vs 695/849 (82%); p4 years prior to the data collection, HPV vaccine knowledge was higher among females than males, and a female-gendered perception of HPV vaccine remains prevalent. Internet and social media were minor HPV vaccine information sources. Study findings demonstrate that HPV knowledge matters for HPV vaccine uptake and suggest that we should improve HPV information quality and access for youth, particularly by tailoring knowledge campaigns to young men.