A retrospective analysis of a phase III infliximab psoriasis trial was conducted to assess whether the Target Nail Psoriasis Severity Index (tnNAPSI) reflects the number of nails affected (NNAIL) and their improvement with treatment. At baseline 81% of patients (305/378) had nail psoriasis with mean NNAIL and tnNAPSI scores of 7.5 and 4.5, respectively. NNAIL and tnNAPSI scores were positively correlated (R = 0.58; P < 0.001). Infliximab therapy significantly reduced NNAIL and tnNAPSI scores through week 50 and the correlation between the two indices increased from week 10 (R = 0.65) to week 50 (R = 0.83; P < 0.001 for all time points). Thus, tnNAPSI in concert with ...