Accuracy of week 14 infliximab trough levels ≥3.5 µg/mL and CRP decrease ≥60% from baseline at week 14 in predicting sustained response in patients with raised baseline CRP >8 µg/mL given infliximab 5 mg/kg every 8 weeks without dose escalation (n=71)
| IFX level | CRP change from baseline | IFX level and CRP change from baseline | IFX level or CRP change from baseline | |
|---|---|---|---|---|
| Optimal cut-off point | 3.5 µg/mL | 60% | 3.5 µg/mL and 60% | 3.5 µg/mL or 60% |
| Sensitivity | 0.64 | 0.91 | 0.59 | 0.95 |
| Specificity | 0.78 | 0.53 | 0.82 | 0.49 |
| PPV | 0.56 | 0.47 | 0.59 | 0.46 |
| NPV | 0.83 | 0.93 | 0.82 | 0.96 |
CRP, C reactive protein; IFX, infliximab; NPV, negative predictive value; PPV, positive predictive value.