title: Determinants of loss to follow-up in patients on antiretroviral treatment, South Africa, 2004-2012: a cohort study.
abstract: BACKGROUND
  The number of Human Immunodeficiency Virus (HIV) infected people eligible for initiation on antiretroviral Therapy (ART) is increasing. ART programmatic success requires that patients who are taking ART remain on treatment and are followed up regularly. This study investigated factors associated with being lost to follow-up, in a cohort of patients enrolled in a pharmacovigilance study in South Africa.
  
  
  METHODS
  This was a retrospective observational cohort study performed at one of the Medunsa National Pharmacovigilance Centre's (MNPC) ART sentinel surveillance sites. Loss to Follow-up (LTFU) was defined as "a patient who had been followed up at the sentinel site, who had not had contact with the health facility for 180 days or more since their last recorded expected date of return or if there were 180 days or more between the expected date of return and the next clinic visit".
  
  
  RESULTS
  Out of 595 patients, 65.5% (n = 390) were female and 23.4% (n = 139) were LTFU. The median time on ART before LTFU was 21.5 months (interquartile range: 12.9 - 34.7 months). The incidence rate of LTFU was 103 per 1000 person-years in the first year on ART and increased to 405 per 1000 person-years in the eighth year of taking ART. Factors associated with becoming LTFU included not having a committed partner (Adjusted Hazard Ratio (aHR): 2.9, 95% Confidence Interval (CI):1.19-6.97, p = 0.019), being self-employed (aHR: 13.9, 95% CI:2.81 - 69.06, p = 0.001), baseline CD4 count > 200 cells/ml (aHR: 3.8, 95% CI: 1.85-7.85, p < 0.001), detectable last known Viral Load (VL) (aHR: 3.6, 95% CI:1.98-6.52, p < 0.001) and a last known World Health Organisation clinical stage three or four (aHR: 2.0, 95% CI:1.22-3.27, p = 0.006). Patients that previously had an ART adverse event had a lower risk (aHR: 0.6, 95% CI: 0.38 - 0.99, p = 0.044) of becoming LTFU than those that had not.
  
  
  CONCLUSIONS
  The incidence rate of LTFU increases with additional years on ART. Intensified measures to improve patient retention on ART must be prioritised with increasing patient time on ART and in patients that are at increased risk of becoming lost to follow-up.
authors.affiliation: South African Field Epidemiology Training Programme, National Institute for Communicable Diseases of the National Health Laboratory Services, 1 Modderfontein Road, Monument Park 0105, Post net suite 179, P/bag X27923, Sandringham, South Africa. mazvita1979@gmail.com.|School of Health Systems and Public Health, Faculty of Health Sciences, University of Pretoria, Pretoria, Dr Savage Road 0084 Pinshof 349, Pretoria, South Africa. mazvita1979@gmail.com.|Medunsa National Pharmacovigilance Centre, Medunsa Campus, University of Limpopo, Pretoria, South Africa. mazvita1979@gmail.com.|Wits Reproductive Health and HIV Institute, 22 Esselen Street, Hillbrow, South Africa. mazvita1979@gmail.com.
authors.forename: Mazvita Naome
authors.initials: MN
authors.lastname: Mberi
authors.affiliation: South African Field Epidemiology Training Programme, National Institute for Communicable Diseases of the National Health Laboratory Services, 1 Modderfontein Road, Monument Park 0105, Post net suite 179, P/bag X27923, Sandringham, South Africa. LazarusK@nicd.ac.za.|School of Health Systems and Public Health, Faculty of Health Sciences, University of Pretoria, Pretoria, Dr Savage Road 0084 Pinshof 349, Pretoria, South Africa. LazarusK@nicd.ac.za.
authors.forename: Lazarus Rugare
authors.initials: LR
authors.lastname: Kuonza
authors.affiliation: South African Field Epidemiology Training Programme, National Institute for Communicable Diseases of the National Health Laboratory Services, 1 Modderfontein Road, Monument Park 0105, Post net suite 179, P/bag X27923, Sandringham, South Africa. ngumede@yahoo.com.
authors.forename: Nomathemba Michelle
authors.initials: NM
authors.lastname: Dube
authors.affiliation: National Institute for Occupational Health, Smit Street, Braamfontein, South Africa. Cornelius.nattey@nioh.nhls.ac.za.|Global Partnership Initiated Academia for the control of health threats, Bernard Nocht Institute for Tropical Medicine, Bernad-Nocht Street 74, 20259, Hamburg, Germany. Cornelius.nattey@nioh.nhls.ac.za.
authors.forename: Cornelius
authors.initials: C
authors.lastname: Nattey
authors.affiliation: Biostatistics Research unit, South African Medical Research Council, 1 Soutpansberg Road, Pretoria, South Africa. Samuel.Manda@mrc.ac.za.|Division of Epidemiology and biostatistics, School of Public Health, University of the Witwatersrand, 27 St Andrews Road Parktown, Johannesburg, South Africa. Samuel.Manda@mrc.ac.za.
authors.forename: Samuel
authors.initials: S
authors.lastname: Manda
authors.affiliation: Medunsa National Pharmacovigilance Centre, Medunsa Campus, University of Limpopo, Pretoria, South Africa. randbsummers@mweb.ac.za.|Department of Pharmacy, Faculty of Health Sciences, MEDUNSA Campus, University of Limpopo, Pretoria, South Africa. randbsummers@mweb.ac.za.
authors.forename: Robert
authors.initials: R
authors.lastname: Summers
mesh_terms: D000328:Adult; D044966:Anti-Retroviral Agents / Q000627:therapeutic use*; D018791:CD4 Lymphocyte Count; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000453:epidemiology; D006801:Humans; D059012:Lost to Follow-Up; D008297:Male; D008875:Middle Aged; D060735:Pharmacovigilance; D012189:Retrospective Studies; D012747:Sexual Partners; D013019:South Africa / Q000453:epidemiology; D019562:Viral Load; D014944:World Health Organization
chemical_list: D044966:Anti-Retroviral Agents