Sensitivity and specificity of CRP and symptom screening as tuberculosis screening tools among HIV-positive and negative outpatients at a primary healthcare facility in Lusaka, Zambia: a prospective cross-sectional study
Bibliographic record
Abstract
OBJECTIVES: To evaluate the performance of point-of-care C-reactive protein (CRP) as a screening tool for tuberculosis (TB) using a threshold of 10 mg/L in both people living with HIV (PLHIV) and HIV-negative individuals and compare it to symptom screening using a composite reference for bacteriological confirmation of TB. METHODS: Prospective cross-sectional study. SETTING: A primary healthcare facility in Lusaka, Zambia. PARTICIPANTS: Consecutive adults (≥18 years) presenting for routine outpatient healthcare were enrolled. Of the 816 individuals approached to participate in the study, 804 eligible consenting adults were enrolled into the study, of which 783 were included in the analysis. PRIMARY OUTCOME MEASURES: Sensitivity, specificity, positive predictive value and negative predictive value (NPV) of CRP and symptom screening. RESULTS: Overall, sensitivity of WHO-recommended four-symptom screen (W4SS) and CRP were 87.2% (80.0-92.5) and 86.6% (79.6-91.8) while specificity was 30.3% (26.7-34.1) and 34.8% (31.2-38.6), respectively. Among PLHIV, sensitivity of W4SS and CRP was 92.2% (81.1-97.8) and 94.8% (85.6-98.9) while specificity was 37.0% (31.3-43.0) and 27.5% (22.4-33.1), respectively. Among those with CD4≥350, the NPV for CRP was 100% (92.9-100). In the HIV negative, sensitivity of W4SS and CRP was 83.8% (73.4-91.3) and 80.3% (69.5-88.5) while specificity was 25.4% (20.9-30.2) and 40.5% (35.3-45.6), respectively. Parallel use of CRP and W4SS yielded a sensitivity and NPV of 100% (93.8-100) and 100% (91.6-100) among PLHIV and 93.3% (85.1-97.8) and 90.0% (78.2-96.7) among the HIV negatives, respectively. CONCLUSION: Sensitivity and specificity of CRP were similar to symptom screening in HIV-positive outpatients. Independent use of CRP offered limited additional benefit in the HIV negative. CRP can independently accurately rule out TB in PLHIV with CD4≥350. Parallel use of CRP and W4SS improves sensitivity irrespective of HIV status and can accurately rule out TB in PLHIV, irrespective of CD4 count.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.007 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".