Evaluation of the Arkansas method of urine testing for isoniazid in South Africa

Int J Tuberc Lung Dis. 2007 Nov;11(11):1232-6.

Abstract

Setting: A South African hospital serving gold mine employees.

Objective: To determine the sensitivity and specificity of the Arkansas method for detecting isoniazid (INH) metabolites among South African adults and to examine the effect of smoking status on positive results.

Design: Urine specimens were collected from in-patients taking INH as part of tuberculosis treatment at 6, 12 and 24 h after a directly observed 300 mg oral dose. As a control group, a single urine specimen was collected from surgical in-patients not taking INH. Specimens were tested for INH using a commercially available dipstick.

Results: A total of 153 patients on INH and 60 controls were recruited. The sensitivity of the test was 93.3% (95%CI 88.1-96.8) at 6 h post INH, 93.4% (95%CI 88.2-96.8) at 12 h and 77% (95%CI 69.1-83.7) at 24 h. The specificity of the test was 98.3% (95%CI 91.1->99.9). There was no association between smoking status and colour change of positive results.

Conclusions: This test is a useful method of monitoring adherence to TB treatment or preventive therapy among South Africans. However, it is less than 100% sensitive, especially with increasing time post dose, which should be taken into consideration when interpreting results for individual patients.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antitubercular Agents / administration & dosage
  • Antitubercular Agents / therapeutic use
  • Antitubercular Agents / urine*
  • Cross-Sectional Studies
  • Humans
  • Isoniazid / urine*
  • Male
  • Middle Aged
  • Patient Compliance
  • Sensitivity and Specificity
  • Smoking
  • South Africa
  • Tuberculosis / drug therapy*

Substances

  • Antitubercular Agents
  • Isoniazid