Hanifa, Y; Mngadi, K; Lewis, J; Fielding, K; Churchyard, G; Grant, AD; (2007) Evaluation of the Arkansas method of urine testing for isoniazid in South Africa. The international journal of tuberculosis and lung disease, 11 (11). pp. 1232-1236. ISSN 1027-3719 https://researchonline.lshtm.ac.uk/id/eprint/8380
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https://researchonline.lshtm.ac.uk/id/eprint/8380
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.