DAS28 best reflects the physician's clinical judgment of response to infliximab therapy in rheumatoid arthritis patients: validation of the DAS28 score in patients under infliximab treatment

Table 4 Performance at different cut-offs of DAS28 at week 22 for dose increase

DAS cut-off	Sensitivity	Specificity	PPV	NPV	Accuracy
2.0	0.99	0.13	0.23	0.98	0.31
2.5	0.99	0.22	0.25	0.99	0.38
2.6	0.99	0.26	0.26	0.99	0.41
3.0	0.98	0.38	0.29	0.98	0.50
3.2	0.96	0.46	0.32	0.98	0.57
4.0	0.79	0.66	0.38	0.92	0.68
4.5	0.76	0.77	0.47	0.92	0.77
5.0	0.58	0.87	0.55	0.89	0.81
5.1	0.53	0.88	0.55	0.88	0.81
5.5	0.43	0.95	0.69	0.86	0.84
6.0	0.34	0.97	0.73	0.85	0.83
6.5	0.19	0.98	0.72	0.82	0.81

DAS, disease activity score; PPV, positive predictive value (predictive value to give a dose increase as a measure of insufficient response); NPV, negative predictive value (predictive value to continue on the current dose as a measure of good response); PPV, NPV and accuracy were calculated using the following formulae:
c) Accuracy = sensitivity* a_priori_chance + specificity* (1-a_priori_chance)
The a priori chance is given by the percentage of patients that need a dose increase as a measure of insufficient response.

ISSN: 1478-6362