title: High HIV incidence among persons who inject drugs in Pakistan: greater risk with needle sharing and injecting frequently among the homeless.
abstract: BACKGROUND
  The incidence of HIV among persons who inject drugs (PWIDU) has fallen in many nations, likely due to successes of clean needle/syringe exchange and substance abuse treatment and service programs. However in Pakistan, prevalence rates for PWID have risen dramatically. In several cities, prevalence exceeded 20% by 2009 compared to a 2003 baseline of just 0.5%. However, no cohort study of PWID has ever been conducted.
  
  
  METHODS
  We enrolled a cohort of 636 HIV seronegative PWID registered with three drop-in centers that focus on risk reduction and basic social services in Karachi. Recruitment began in 2009 (March to June) and PWID were followed for two years. We measured incidence rates and risk factors associated with HIV seroconversion.
  
  
  RESULTS
  Incidence of HIV was 12.4 per 100 person-years (95% exact Poisson confidence interval [CI]: 10.3-14.9). We followed 474 of 636 HIV seronegative persons (74.5%) for two years, an annual loss to follow-up of <13 per 100 person years. In multivariable Cox regression analysis, HIV seroconversion was associated with non-Muslim religion (Adjusted risk ratio [ARR] = 1.7, 95%CI:1.4, 2.7, p = 0.03), sharing of syringes (AR  = 2.3, 95%CI:1.5, 3.3, p<0.0001), being homeless (ARR = 1.7, 95%CI:1.1, 2.5, p = 0.009), and daily injection of drugs (ARR = 1.1, 95%CI:1.0, 1.3, p = 0.04).
  
  
  CONCLUSIONS
  Even though all members of the cohort of PWID were attending risk reduction programs, the HIV incidence rate was very high in Karachi from 2009-2011. The project budget was low, yet we were able to retain three-quarters of the population over two years. Absence of opiate substitution therapy and incomplete needle/syringe exchange coverage undermines success in HIV risk reduction.
authors.affiliation: Bridge Consultants Foundation, Karachi, Pakistan ; Department of Community Health Sciences, Aga Khan University, Karachi, Pakistan.
authors.forename: Rab Nawaz
authors.initials: RN
authors.lastname: Samo
authors.affiliation: Bridge Consultants Foundation, Karachi, Pakistan.
authors.forename: Arshad
authors.initials: A
authors.lastname: Altaf
authors.affiliation: Department of Community Health Sciences, Aga Khan University, Karachi, Pakistan.
authors.forename: Ajmal
authors.initials: A
authors.lastname: Agha
authors.affiliation: Department of Community Health Sciences, Aga Khan University, Karachi, Pakistan.
authors.forename: Omrana
authors.initials: O
authors.lastname: Pasha
authors.affiliation: Department of Community Health Sciences, Aga Khan University, Karachi, Pakistan.
authors.forename: Shafquat
authors.initials: S
authors.lastname: Rozi
authors.affiliation: Sindh AIDS Control Programme, Karachi, Pakistan.
authors.forename: Ashraf
authors.initials: A
authors.lastname: Memon
authors.affiliation: Pakistan Society, Karachi, Pakistan.
authors.forename: Saleem
authors.initials: S
authors.lastname: Azam
authors.affiliation: Vanderbilt Institute for Global Health and Departments of Biostatistics & Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America.
authors.forename: Meridith
authors.initials: M
authors.lastname: Blevins
authors.affiliation: Vanderbilt Institute for Global Health and Departments of Biostatistics & Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America.
authors.forename: Sten H
authors.initials: SH
authors.lastname: Vermund
authors.affiliation: Bridge Consultants Foundation, Karachi, Pakistan.
authors.forename: Sharaf Ali
authors.initials: SA
authors.lastname: Shah
mesh_terms: D000328:Adult; D005260:Female; D015658:HIV Infections / Q000453:epidemiology*; D006679:HIV Seropositivity / Q000453:epidemiology*; D006703:Ill-Housed Persons; D006801:Humans; D015994:Incidence; D008297:Male; D016485:Needle Sharing / Q000706:statistics & numerical data*; D018671:Needle-Exchange Programs; D010154:Pakistan; D015819:Substance Abuse, Intravenous / Q000453:epidemiology*; D013594:Syringes