title: Cardio-Thoracic Ratio Is Stable, Reproducible and Has Potential as a Screening Tool for HIV-1 Related Cardiac Disorders in Resource Poor Settings.
abstract: BACKGROUND
  Cardiovascular disorders are common in HIV-1 infected persons in Africa and presentation is often insidious. Development of screening algorithms for cardiovascular disorders appropriate to a resource-constrained setting could facilitate timely referral. Cardiothoracic ratio (CTR) on chest radiograph (CXR) has been suggested as a potential screening tool but little is known about its reproducibility and stability. Our primary aim was to evaluate the stability and the inter-observer variability of CTR in HIV-1 infected outpatients. We further evaluated the prevalence of cardiomegaly (CTR≥0.5) and its relationship with other risk factors in this population.
  
  
  METHODS
  HIV-1 infected participants were identified during screening for a tuberculosis vaccine trial in Khayelitsha, South Africa between August 2011 and April 2012. Participants had a digital posterior-anterior CXR performed as well as history, examination and baseline observations. CXRs were viewed using OsiriX software and CTR calculated using digital callipers.
  
  
  RESULTS
  450 HIV-1-infected adults were evaluated, median age 34 years (IQR 30-40) with a CD4 count 566/mm3 (IQR 443-724), 70% on antiretroviral therapy (ART). The prevalence of cardiomegaly was 12.7% (95% C.I. 9.6%-15.8%). CTR was calculated by a 2nd reader for 113 participants, measurements were highly correlated r = 0.95 (95% C.I. 0.93-0.97) and agreement of cardiomegaly substantial κ = 0.78 (95% C.I 0.61-0.95). CXR were repeated in 51 participants at 4-12 weeks, CTR measurements between the 2 time points were highly correlated r = 0.77 (95% C.I 0.68-0.88) and agreement of cardiomegaly excellent κ = 0.92 (95% C.I. 0.77-1). Participants with cardiomegaly had a higher median BMI (31.3; IQR 27.4-37.4) versus 26.9; IQR 23.2-32.4); p<0.0001) and median systolic blood pressure (130; IQR 121-141 versus 125; IQR 117-135; p = 0.01).
  
  
  CONCLUSIONS
  CTR is a robust measurement, stable over time with substantial inter-observer agreement. A prospective study evaluating utility of CXR to identify cardiovascular disorder in this population is warranted.
authors.affiliation: Institute of Infectious Diseases and Molecular Medicine, Clinical Infectious Disease Research Initiative, University of Cape Town, Cape Town, South Africa.|Department of Medicine, Imperial College London, London, United Kingdom.|Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.
authors.forename: Hanif
authors.identifier: http://orcid.org/0000-0002-4278-9316
authors.initials: H
authors.lastname: Esmail
authors.affiliation: Institute of Infectious Diseases and Molecular Medicine, Clinical Infectious Disease Research Initiative, University of Cape Town, Cape Town, South Africa.|School of Public Health and Family Medicine, Division of Public Health Medicine, University of Cape Town, Cape Town, South Africa.
authors.forename: Tolu
authors.initials: T
authors.lastname: Oni
authors.affiliation: Institute of Infectious Diseases and Molecular Medicine, Clinical Infectious Disease Research Initiative, University of Cape Town, Cape Town, South Africa.|Department of Medicine, University of Cape Town, Cape Town, South Africa.
authors.forename: Friedrich
authors.initials: F
authors.lastname: Thienemann
authors.affiliation: Institute of Infectious Diseases and Molecular Medicine, Clinical Infectious Disease Research Initiative, University of Cape Town, Cape Town, South Africa.
authors.forename: Nashreen
authors.initials: N
authors.lastname: Omar-Davies
authors.affiliation: Institute of Infectious Diseases and Molecular Medicine, Clinical Infectious Disease Research Initiative, University of Cape Town, Cape Town, South Africa.|Department of Medicine, Imperial College London, London, United Kingdom.|Department of Medicine, University of Cape Town, Cape Town, South Africa.|The Francis Crick Institute, Mill Hill Laboratory, London, United Kingdom.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Wilkinson
authors.affiliation: Department of Medicine, Division of Cardiology, University of Cape Town, Cape Town, South Africa.
authors.forename: Mpiko
authors.initials: M
authors.lastname: Ntsekhe
mesh_terms: D000328:Adult; D006332:Cardiomegaly / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D005260:Female; D015658:HIV Infections / Q000150:complications*; D015497:HIV-1; D006295:Health Resources; D006331:Heart Diseases / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D008297:Male; D008403:Mass Screening; D009929:Organ Size; D013902:Radiography, Thoracic / Q000379:methods / Q000592:standards; D015203:Reproducibility of Results; D012307:Risk Factors; D013019:South Africa / Q000453:epidemiology