Table 2. Diagnostic variables associated with either single or combined tests for predicting positive blood culture.
Diagnostic variables associated with elevation of either procalcitonin (PCT ≥ 0.5 ng/ml), blood lactate (LAC ≥ 19.8 mg/dl), or high-sensitivity C-reactive protein (hs-CRP ≥ 0.8 mg/dl), two variables, and all variables for predicting positive blood culture.
| Pattern (n) | Sensitivity (95% confidence interval, CI) | Specificity (95% CI) | Overall accuracy (= Diagnostic effectiveness) (95% CI) | Positive-test likelihood (95% CI) | Negative-test likelihood (95% CI) | Odds ratio (95% CI) | Pvalue |
|---|---|---|---|---|---|---|---|
| Elevated lactate (n = 381) | 0.63 (0.56–0.7) | 0.63 (0.59–0.66) | 0.63 (0.60–0.66) | 1.71 (1.47–1.96) | 0.58 (0.48–0.7) | 2.93 (2.09–4.14) | <0.0001 |
| Elevated PCT (n = 527) | 0.81 (0.74–0.86) | 0.47 (0.43–0.50) | 0.54 (0.51–0.57) | 1.51 (1.36–1.66) | 0.41 (0.31–0.55) | 3.64 (2.46–5.51) | <0.0001 |
| Elevated hs-CRP (n = 785) | 0.88 (0.82–0.92) | 0.11 (0.09–0.14) | 0.28 (0.25–0.31) | 0.99 (0.92–1.04) | 1.09 (0.71–1.66) | 0.91 (0.55–1.55) | 0.79 |
| Elevated lactate and PCT (n = 255) | 0.53 (0.46–0.6) | 0.78 (0.75–0.81) | 0.72 (0.69–0.75) | 2.41 (1.98–2.91) | 0.60 (0.51–0.70) | 3.98 (2.81–5.63) | <0.0001 |
| Elevated lactate and/or PCT (n = 653) | 0.91 (0.87–0.95) | 0.31 (0.28–0.35) | 0.45 (0.41–0.48) | 1.33 (1.24–1.42) | 0.28 (0.17–0.43) | 4.83 (2.84–8.69) | <0.0001 |
| Elevated hs-CRP and PCT (n = 497) | 0.76 (0.69–0.81) | 0.49 (0.46–0.53) | 0.55 (0.52–0.59) | 1.5 (1.34–1.66) | 0.49 (0.38–0.63) | 3.04 (2.1–4.44) | <0.0001 |
| Elevated hs-CRP and/or PCT (n = 815) | 0.93 (0.88–0.96) | 0.08 (0.06–0.11) | 0.27 (0.24–0.3) | 1.01 (0.96–1.05) | 0.86 (0.49–1.49) | 1.18 (0.63–2.34) | 0.70 |
| Elevated lactate and hs-CRP (n = 329) | 0.55 (0.48–0.62) | 0.68 (0.64–0.71) | 0.65 (0.62–0.68) | 1.71 (1.44–2.01) | 0.67 (0.56–0.78) | 2.57 (1.84–3.6) | <0.0001 |
| Elevated lactate and/or hs-CRP (n = 837) | 0.96 (0.93–0.99) | 0.06 (0.04–0.08) | 0.26 (0.23–0.29) | 1.03 (0.99–1.06) | 0.58 (0.27–1.24) | 1.76 (0.77–4.72) | 0.23 |
| Elevated lactate and PCT and hs-CRP (n = 234) | 0.48 (0.41–0.55) | 0.80 (0.77–0.83) | 0.73 (0.7–0.76) | 2.39 (1.94–2.93) | 0.65 (0.56–0.74) | 3.68 (2.59–5.22) | <0.0001 |
Notes.
- N
- 886
- n
- number of samples within the pattern
Interpretation of results: negative-test likelihood <0.6 will indicate clinical usefulness.