The interpretation of nucleic acid amplification tests for tuberculosis: do rapid tests change treatment decisions?
OBJECTIVE
To describe changes in treatment decisions after receipt of nucleic acid amplification (NAA) test for the diagnosis of M. tuberculosis.


METHODS
Retrospective notes review of treatment decisions in patients receiving a NAA test for suspected pulmonary or non-pulmonary tuberculosis at the Royal Free Hospital in London between March 2001 and February 2002. Notes were sought on a 50% random sample of patients with both smear and NAA negative specimens and all patients with other specimen results.


RESULTS
Two hundred and fifty patients were tested with NAA; clinical details were obtained on 138; 61 were ever treated. Seventeen (17/18) smear-negative patients were started on treatment after a positive NAA; none of six smear-negative patients treated prior to a negative NAA result had treatment stopped. Seventeen (17/21) smear-positive patients were treated prior to NAA result and all were NAA positive; treatment was delayed in four smear-positive patients until receipt of an NAA and one NAA-negative patient was not treated.


CONCLUSIONS
In routine practice a positive test in an untreated smear-negative patient leads to decision to treat in almost all, but the proportion testing positive is low (8% or 17/219). In patients already on treatment negative tests did not lead to decisions to stop.
Conaty
S J
SJ
Department of Primary Care and Population Science, UCL Centre for Infectious Disease Epidemiology, Royal Free and University College Medical School, Royal Free Campus, London NW3 2PF, UK. s.conaty@pcps.ucl.ac.uk
Claxton
A P
AP
Enoch
D A
DA
Hayward
A C
AC
Lipman
M C I
MC
Gillespie
S H
SH
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000995:Antitubercular Agents / Q000627:therapeutic use*; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D021141:Nucleic Acid Amplification Techniques; D010818:Practice Patterns, Physicians'; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D013183:Sputum / Q000382:microbiology; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000188:drug therapy
D000995:Antitubercular Agents