Diagnosing smear-negative tuberculosis using case definitions and treatment response in HIV-infected adults.
OBJECTIVE
To assess the diagnostic utility of expanded case definitions for HIV-associated smear-negative pulmonary tuberculosis (PTB) and extra-pulmonary TB (EPTB), and to derive objective criteria for response to anti-tuberculosis treatment.


METHODS
A prospective cohort study of HIV-infected adults who met expanded clinical case definitions for smear-negative PTB and EPTB.


METHODS
All participants were started on rifampicin-based anti-tuberculosis treatment after mycobacterial cultures from multiple sites. At weeks 2, 4 and 8, response to treatment (RTT) was assessed by measuring changes in weight, haemoglobin, C-reactive protein, Karnofsky performance score and symptom count ratio.


RESULTS
Of 147 participants enrolled, 105 (71%) were diagnosed with definite (culture-positive) or probable (histological features) TB and 25 (17%) with possible TB (treatment response). The positive predictive value for the most common case definitions ranged from 89% to 96%. Significant improvements in all the RTT parameters occurred in the subjects with confirmed TB (P < 0.001). Clinically relevant RTT criteria were derived, two or more of which were met at week 8 in 97.5% of subjects with confirmed TB, 91.3% of subjects with possible TB and none of the subjects without TB.


CONCLUSIONS
Expanded case definitions could enhance the diagnosis of PTB and EPTB in HIV-infected adults in resource-limited settings. Using objective criteria, RTT can be assessed within 8 weeks of initiating anti-tuberculosis treatment.
Wilson
D
D
Department of Medicine, Division of Infectious Diseases, University of Cape Town, Cape Town, South Africa.
Nachega
J
J
Morroni
C
C
Chaisson
R
R
Maartens
G
G
D017088:AIDS-Related Opportunistic Infections / Q000175:diagnosis* / Q000188:drug therapy; D000328:Adult; D000904:Antibiotics, Antitubercular / Q000627:therapeutic use; D002097:C-Reactive Protein / Q000032:analysis; D015331:Cohort Studies; D005260:Female; D015658:HIV Infections / Q000150:complications*; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D017567:Karnofsky Performance Status; D008297:Male; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification; D011237:Predictive Value of Tests; D012293:Rifampin / Q000627:therapeutic use; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D014376:Tuberculosis / Q000150:complications / Q000175:diagnosis* / Q000188:drug therapy
D000904:Antibiotics, Antitubercular; D006454:Hemoglobins; D002097:C-Reactive Protein; D012293:Rifampin