title: Incidence and risk factors of AIDS-defining cancers in a cohort of HIV-positive adults: Importance of the definition of incident cases.
abstract: BACKGROUND
  The aim of this study was to investigate the incidence and risk factors for the development of AIDS-defining cancers (ADCs); and to investigate the effect of making different assumptions on the definition of incident cases.
  
  
  METHODS
  A multicentre cohort study was designed. Poisson regression was used to assess incidence and risk factors. To account for misclassification, incident cases were defined using lag-times of 0, 14 and 30 days after enrolment.
  
  
  RESULTS
  A total of 6393 HIV-positive subjects were included in the study. The incidences of ADCs changed as the lag periods were varied from 0 to 30 days. Different risk factors emerged as the definition of incident cases was changed. For a lag time of 0, the risk of Kaposi sarcoma [KS] and non-Hodgkin lymphoma [NHL] increased at CD4 counts <200/ml. HAART was associated with lower risk of NHL and KS. Men who had sex with men had a higher risk of KS. KS and NHL were not associated with viral load, gender, or hepatitis B or C. The results were similar for a lag-time of 14 and 30 days; however, hepatitis C was significantly associated with NHL.
  
  
  CONCLUSIONS
  This analysis shows the importance of the definition of incident cases in cohort studies. Alternative definitions gave different incidence estimates, and may have implications for the analysis of risk factors.
authors.affiliation: Grupo de Enfermedades Infecciosas, Servicio de Medicina Interna, Hospital Infanta Sofía, San Sebastián de los Reyes, Madrid, Spain. inessuarez@hotmail.com
authors.forename: Inés
authors.initials: I
authors.lastname: Suárez-García
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Jarrín
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Iribarren
authors.forename: Luis Fernando
authors.initials: LF
authors.lastname: López-Cortés
authors.forename: José
authors.initials: J
authors.lastname: Lacruz-Rodrigo
authors.forename: Mar
authors.initials: M
authors.lastname: Masiá
authors.forename: Juan Luis
authors.initials: JL
authors.lastname: Gómez-Sirvent
authors.forename: José
authors.initials: J
authors.lastname: Hernández-Quero
authors.forename: Francesc
authors.initials: F
authors.lastname: Vidal
authors.forename: Belén
authors.initials: B
authors.lastname: Alejos-Ferreras
authors.forename: Santiago
authors.initials: S
authors.lastname: Moreno
authors.forename: Julia
authors.initials: J
authors.lastname: Del Amo
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000150:complications* / Q000175:diagnosis*; D000328:Adult; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D006679:HIV Seropositivity / Q000150:complications*; D006801:Humans; D015994:Incidence; D016483:Lymphoma, AIDS-Related / Q000453:epidemiology*; D008228:Lymphoma, Non-Hodgkin / Q000453:epidemiology* / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012514:Sarcoma, Kaposi / Q000453:epidemiology* / Q000209:etiology*