Diagnostic test(s) | HIV-infected patients with CD4 count >200 cells per mL | HIV-infected patients with CD4 count ≤200 cells per mL | ||||||||
Group 1 patients | Group 2 patients | Group 1 patients | Group 2 patients | |||||||
Microbiological reference (M. tuberculosis culture positive versus negative) | Composite reference standard (definite- and probable-TB versus non-TB) | Microbiological reference (M. tuberculosis culture positive versus negative) | Composite reference standard (definite- and probable-TB versus non-TB) | |||||||
Sensitivity | Specificity | Sensitivity | Specificity | Specificity | Sensitivity | Specificity | Sensitivity | Specificity | Specificity | |
Subjects n | 55 | 55 | 84 | 173 | 147 | 84 | ||||
Rapid smear microscopy | 58 (39–75) 15/26 | 90 (79–100) 26/29 | 38 (25–52) 17/45 | 95 (55–100) 9/10 | No results | 56++ (45–66) 45/81 | 91##,§§ (86–97) 84/92 | 44## (36–53) 58/131 | 100 (79–100) 16/16 | No results |
LAM ELISA | 27*** (14–46) 7/26 | 89** (77–100) 24/27 | 28*** (17–43) 12/43 | 100 (69–100) 10/10 | 100** (93–100) 53/53 | 70** (59–79) 56/80 | 76§§,** (67–85) 69/91 | 59*** (50–67) 76/129 | 94 (70–100) 15/16 | 97** (90–100) 28/29 |
LAM strip-test (grade 1 cut-off point) | 54 (36–71) 14/26 | 76 (60–91) 22/29 | 49 (35–63) 22/45 | 100 (69–100) 10/10 | 91¶¶ (83–99) 49/54 | 72 (61–80) 58/81 | 61# (51–71) 56/92 | 64 (56–72) 84/131 | 94 (70–100) 15/16 | 87# (75–99) 26/30 |
LAM strip-test (grade 2 cut-off point) | 27¶ (14–46) 7/26 | 83§ (69–97) 24/29 | 29+ (18–43) 13/45 | 100 (69–100) 10/10 | 100§,¶¶ (93–100) 54/54 | 58¶,¶¶ (47–68) 47/81 | 72ƒ (63–81) 66/92 | 52+,++ (43–60) 68/131 | 94 (70–100) 15/16 | 97ƒ (90–100) 29/30 |
LAM strip-test (grade 2 cut-off point) in smear-negative/sputum scarce M. tuberculosis culture-positive patients | 0 (0–26) 0/11 | N/A | 14 (6–32) | N/A | N/A | 51 (36–66) 21/41 | N/A | 43 (32–54) 31/73 | N/A | N/A |
Combined sputum smear microscopy and LAM strip-test (grade 2 cut-off point) | 58 (39–75) 15/26 | 79 (65–94) 23/29 | 47** (33–61) 21/45 | 95 (55–100) 9/10 | No results | 75¶¶,++ (65–83) 61/81 | 70**,## (60–79) 64/92 | 68**,##,++ (60–75) 89/131 | 100** (79–100) 16/16 | No results |
Data are presented as sensitivity/specificity (95% CI) n/ntotal, unless otherwise stated. N/A: not applicable. Using the microbiological reference, 14 out of the 242 HIV-infected group 1 patients had no CD4 cell count data, leaving 228 patients for the above analysis. 107 Mycobacterium tuberculosis (M. tuberculosis) culture-positive group 1 patients were used for the sensitivity calculations and 121 M. tuberculosis culture-negative group 1 for specificity calculations. Using the composite reference, 12 out of of the 218 HIV-infected group 1 patients had no CD4 cell count data, leaving 202 patients for the above analysis. 176 definite- and probable-tuberculosis (TB) were used for the sensitivity calculations and 26 non-TB patients for specificity calculations. Additionally, 84 non-TB group 2 patients were used for a second specificity calculation. Rapid (within 24 h of hospitalisation) smear microscopy includes both sputum and non-sputum samples (e.g. fine-needle aspirate and cerebrospinal fluid samples). Two CD4 >200 cells per mL and CD4 ≤200 cells per mL group 1 patients (analysis 1) and three CD4 >200 and CD4 ≤200 (analysis 2) had a missing LAM ELISA result while one CD4 >200 (analysis 2) had a missing LAM strip-test result. For a comparison of differences in diagnostic accuracy measures between analyses and patient groups for a specific test (LAM ELISA or LAM strip-test) p-values were p<0.05; specific p-values: **: p =0.01; ***: p <0.001; #: p =0.009; ¶: p =0.006; +: p =0.008; §: p =0.002; ƒ: p =0.004; nonsignificant p-values are not shown. For a comparison of the specific measures of diagnostic accuracy (sensitivity or specificity) between different tests (LAM ELISA versus LAM strip-test) or combinations thereof, or between different cut-off points of the urine LAM strip-test (grade 1 versus grade 2 cut-off point) p-values were p<0.05; specific p-values: ##: p<0.001; ¶¶: p=0.02; ++: p=0.008; §§: p=0.005; nonsignificant p-values not shown.