title: A prospective study of the risk of tuberculosis among HIV-infected patients.
abstract: OBJECTIVE
  To evaluate the risk of developing active tuberculosis (TB) in a cohort of HIV-1-infected patients.
  
  
  METHODS
  Prospective longitudinal follow-up of 839 HIV-infected patients, of whom 505 (60%) were parenteral drug users and 269 (32%) homosexual men. Tuberculin skin tests were performed at baseline and annually thereafter. Prophylaxis with isoniazid (300 mg daily for 9 months) was offered to those with a positive tuberculin test (induration > or = 5 mm). Diagnosis of TB was accepted if it could be confirmed microbiologically (acid-fast bacilli seen in Ziehl-Neelsen stains or grown in Lowenstein-Jensen cultures) or pathologically (presence of caseating granulomas) and patients had consistent clinical manifestations.
  
  
  RESULTS
  Active TB developed in 23 out of the 733 (3.1%) patients with a negative tuberculin skin test after a mean follow-up of 16 +/- 11 months (range, 2-52 months), with an estimated cumulative probability of 1.5 and 7% after 1 and 3 years, respectively (or 2.4 per 100 patient-years). None of the 87 patients with a negative tuberculin test but a positive Multitest developed TB. Conversely, 106 patients had a positive tuberculin skin test (97 at baseline and nine who converted during follow-up). Active TB developed in seven out of the 26 not receiving prophylaxis or in whom prophylaxis had to be discontinued (16.2 per 100 patient-years), in four out of 61 patients 3-27 months after having completed 9 months of prophylaxis with isoniazid (8.9 per 100 patient-years) and in none of the 19 still receiving isoniazid. When TB was diagnosed, the mean CD4 lymphocyte count of the 34 patients who developed it during follow-up was 77 +/- 103 x 10(6)/l (range, 1-400 x 10(6)/l).
  
  
  CONCLUSIONS
  Among HIV-infected patients in whom the tuberculin skin test is negative, the risk of developing active TB is sufficient to consider prophylaxis if the CD4 count falls below 400 x 10(6)/l, at least in those patients with skin anergy living in high-risk geographical areas such as Spain. When the tuberculin skin test was positive, isoniazid (9 months) provided a 45% protection beyond the period of its administration.
authors.affiliation: Infectious Disease Unit, Hospital Clinic, Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Guelar
authors.forename: J M
authors.initials: JM
authors.lastname: Gatell
authors.forename: J
authors.initials: J
authors.lastname: Verdejo
authors.forename: D
authors.initials: D
authors.lastname: Podzamczer
authors.forename: L
authors.initials: L
authors.lastname: Lozano
authors.forename: E
authors.initials: E
authors.lastname: Aznar
authors.forename: J M
authors.initials: JM
authors.lastname: Miró
authors.forename: J
authors.initials: J
authors.lastname: Mallolas
authors.forename: L
authors.initials: L
authors.lastname: Zamora
authors.forename: J
authors.initials: J
authors.lastname: González
mesh_terms: D017088:AIDS-Related Opportunistic Infections / Q000453:epidemiology*; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007538:Isoniazid / Q000627:therapeutic use; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D014374:Tuberculin Test; D014376:Tuberculosis / Q000150:complications / Q000453:epidemiology* / Q000517:prevention & control
chemical_list: D007538:Isoniazid