Table 4.
Positive and negative predictive values of Determine TB-LAM or Determine TB-LAM and smear microscopy combined when applied to different patient subgroups with differing tuberculosis prevalence
| TB prevalence |
Determine TB-LAM |
Determine TB-LAM and sputum AFB* |
||||
|---|---|---|---|---|---|---|
| Positive predictive value | Negative predictive value | Positive predictive value | Negative predictive value | |||
| All patients (n=516) | 16·5% (13·4–20·0) | 80·0% (61·4–92·3) | 87·4% (84·2–90·3) | 84·1% (69·9–93·4) | 89·8% (86·7–92·4) | |
| CD4 cell count (cells per μL)† | ||||||
| <50 | 28·1% (17·6–40·8) | 92·3% (64·0–99·8) | 90·2% (78·6–96·7) | 92·9% (66·1–99·8) | 90·0% (78·2–96·7) | |
| <100 | 22·7% (15·7–30·9) | 93·8% (69·8–99·8) | 87·5% (79·9–93·0) | 95·0% (75·1–99·9) | 90·7% (83·6–95·5) | |
| <150 | 20·5% (15·4–26·4) | 91·3% (72·0–98·9) | 87·6% (82·2–91·8) | 93·1% (77·2–99·2) | 90·3% (85·2–94·0) | |
| <200 | 18·2% (14·1–22·8) | 88·5% (69·8–97·6) | 88·0% (83·7–91·4) | 88·6% (73·3–96·8) | 90·3% (86·3–93·5) | |
| ≥200 | 13·2% (8·7–18·9) | 66·7% (9·4–99·2) | 87·1% (81·4–91·6) | 75·0% (34·9–96·8) | 89·5% (84·1–93·6) | |
| WHO stage | ||||||
| Stage 1 or 2 | 13·6% (10·2–17·7) | 63·6% (30·8–89·1) | 88·0% (84·1–91·3) | 78·9% (54·4–93·9) | 90·2% (86·4–93·2) | |
| Stage 3 or 4 | 22·4% (16·3–29·4) | 94·4% (72·7–99·9) | 86·8% (80·3–91·7) | 91·7% (73·0–99·0) | 89·7% (83·5–94·1) | |
| WHO symptom screen | ||||||
| Positive | 19·7% (15·7–24·2) | 84·6% (65·1–95·6) | 85·4% (81·1–89·0) | 87·2% (72·6–95·7) | 88·6% (84·6–91·9) | |
| Negative | 9·4% (5·3–15·0) | 66·7% (9·4–99·2) | 92·3% (86·9–96·0) | 75·0% (19·4–99·4) | 93·5% (88·4–96·8) | |
| Any chest-radiograph abnormality‡ | 26·4% (20·9–32·5) | 85·0% (62·1–96·8) | 79·4% (73·4–84·6) | 90·3% (74·2–98·0) | 83·7% (77·9–88·5) | |
Data are % (95% CI) or positive or negative predictive value (95% CI). AFB=acid-fast bacilli. TB=tuberculosis. LAM=lipoarabinomannan.
*
When assessing the predictive values of combined results of Determine TB-LAM and smear microscopy, the positive predictive value was based on either test being positive, and the negative predictive value was based on both tests being negative.
†
514 patients.
‡
470 patients.