title: A pseudo-random patient sampling method evaluated.
abstract: To compare two human immunodeficiency virus (HIV) cohorts to determine whether a pseudo-random sample can represent the entire study population.
  
  
  
  HIV-positive patients receiving care at eight sites in seven Asian countries. The TREAT Asia HIV Observational database (TAHOD) pseudo-randomly selected a patient sample, while TREAT Asia HIV Observational database-Low Intensity Transfer (TAHOD-LITE) included all patients. We compared patient demographics, CD4 count, and HIV viral load testing for each cohort. Risk factors associated with CD4 count response, HIV viral load suppression (<400 copies/mL), and survival were determined for each cohort.
  
  
  
  There were 2,318 TAHOD patients and 14,714 TAHOD-LITE patients. Patient demographics, CD4 count, and HIV viral load testing rates were broadly similar between the cohorts. CD4 count response and all-cause mortality were consistent among the cohorts with similar risk factors. HIV viral load response appeared to be superior in TAHOD and many risk factors differed, possibly due to viral load being tested on a subset of patients.
  
  
  
  Our study gives the first empirical evidence that analysis of risk factors for completely ascertained end points from our pseudo-randomly selected patient sample may be generalized to our larger, complete population of HIV-positive patients. However, results can significantly vary when analyzing smaller or pseudo-random samples, particularly if some patient data are not completely missing at random, such as viral load results.
authors: The Kirby Institute, UNSW Australia, Wallace Wurth Building, Sydney, NSW 2052, Australia. Electronic address: ndelamata@kirby.unsw.edu.au.
authors: Nicole L
authors: NL
authors: De La Mata
authors: Department of Internal Medicine and AIDS Research Institute, Yonsei University College of Medicine, Severance Hospital, Seoul, South Korea.
authors: Mi-Young
authors: MY
authors: Ahn
authors: Chennai Antiviral Research and Treatment Clinical Research Site (CART CRS), YRGCARE Medical Centre, VHS, Chennai, India.
authors: Nagalingeswaran
authors: N
authors: Kumarasamy
authors: National Center for HIV/AIDS, Dermatology & STDs, Phnom Penh, Cambodia.
authors: Penh Sun
authors: PS
authors: Ly
authors: Department of Infectious Diseases, Tan Tock Seng Hospital, Tan Tock Seng, Singapore.
authors: Oon Tek
authors: OT
authors: Ng
authors: National Hospital for Tropical Diseases, Hanoi, Vietnam.
authors: Kinh Van
authors: KV
authors: Nguyen
authors: Department of Internal Medicine, Udayana University, Sanglah Hospital, Bali, Indonesia.
authors: Tuti Parwati
authors: TP
authors: Merati
authors: Bach Mai Hospital, Hanoi, Vietnam.
authors: Thuy Thanh
authors: TT
authors: Pham
authors: Department of Medicine, Queen Elizabeth Hospital, Hong Kong, China.
authors: Man Po
authors: MP
authors: Lee
authors: TREAT Asia, amfAR-The Foundation for AIDS Research, Bangkok, Thailand.
authors: Nicolas
authors: N
authors: Durier
authors: The Kirby Institute, UNSW Australia, Wallace Wurth Building, Sydney, NSW 2052, Australia.
authors: Matthew G
authors: MG
authors: Law
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000627:therapeutic use*; D001208:Asia; D018791:CD4 Lymphocyte Count / Q000706:statistics & numerical data; D015331:Cohort Studies; D016208:Databases, Factual / Q000706:statistics & numerical data; D003710:Demography / Q000706:statistics & numerical data; D015340:Epidemiologic Research Design; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000453:epidemiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D064887:Observational Studies as Topic / Q000706:statistics & numerical data; D011159:Population Surveillance / Q000379:methods*; D012307:Risk Factors; D016019:Survival Analysis; D019562:Viral Load / Q000706:statistics & numerical data
chemical_list: D019380:Anti-HIV Agents
keywords: Asia; Cohort; HIV; Observational data; Patient sampling; Selection bias