爪乾癬の診断に関してN-NAILスコアはNAPSIより高精度
NAPSIとN-NAILはいずれも診断に有用であるが、N-NAILの方がカットオフ値2で高い精度を示した
ラドバウド大学医療センター（オランダ）のEvi C. C. Rikken氏らは、乾癬患者と、乾癬患者にマッチさせた対照群を対象としてコホート研究を実施し、爪の重症度評価ツールであるNAPSIとN-NAILの診断性能を比較検討した。診断特性を決定するため、カットオフ値を定めた。受信者動作特性曲線（ROC曲線）を構築し、さまざまなカットオフ値における感度と特異度を算出した。対象となった乾癬患者104人のうち68人が爪乾癬と診断された。
解析の結果、N-NAILでは、カットオフ値2が乾癬患者群で最も高い精度を示し（感度83.8％、特異度83.3％）、対照群でも同様に最良の値となった（感度83.8％、特異度67.3％）。一方、NAPSIでは、乾癬患者群でカットオフ値7が最適であり（感度80.9％、特異度69.4％）、対照群ではカットオフ値10が最適であった（感度72.1％、特異度70.2％）。
著者らは、「本研究では、尋常性乾癬患者集団の研究に爪乾癬患者を含める際、カットオフ値2のN-NAILの方がNAPSIより高精度であることが示された。スコアリングツールとしてN-NAILを使用するもう一つの利点は、バージョンが1つしかないため、どのツールを使用するかで混乱が生じず、皮膚科医、研究者、爪乾癬に関わる専門家にとって、より簡便かつ迅速に試用することが出来ることである」と述べている。
なお複数の著者が、製薬企業との利益相反（COI）に関する情報を明らかにしている。
N-NAIL Score More Accurate Than NAPSI for Diagnosing Nail Psoriasis
Both NAPSI and N-NAIL provide accurate cutoffs, but better accuracy seen with N-NAIL, with cutoff value of 2
WEDNESDAY, Aug. 27, 2025 (HealthDay News) -- Both the Nail Psoriasis Severity Index (NAPSI) and the Nijmegen-Nail Psoriasis Activity Index Tool (N-NAIL) provide accurate cutoffs for diagnosing nail psoriasis, with better accuracy seen for the N-NAIL, according to a study published online Aug. 24 in the International Journal of Dermatology.
Evi C.C. Rikken, M.D., from the Radboud University Medical Center in Nijmegen, Netherlands, and colleagues conducted a cohort study among patients with psoriasis and matching controls to examine the diagnostic performance of two severity scoring tools: the NAPSI and the N-NAIL, which were used to score fingernails. Cutoff values were established to determine their diagnostic properties. Receiver operating characteristic curves were constructed; for various cutoff points, sensitivity and specificity were calculated.
A total of 104 patients with psoriasis were included, and of these patients, 68 were diagnosed with nail psoriasis. The researchers found that a cutoff value of 2 showed the best accuracy for N-NAIL in the psoriasis population (sensitivity, 83.8 percent; specificity, 83.3 percent) and in the general population (sensitivity, 83.8 percent; specificity, 67.3 percent). A cutoff value of 7 showed the best accuracy for the NAPSI in the psoriasis population (sensitivity, 80.9 percent; specificity, 69.4 percent), while in the general population, a cutoff of 10 was optimal (sensitivity, 72.1 percent; specificity, 70.2 percent).
"This study shows better accuracy for the N-NAIL, with a cutoff value of 2, for the inclusion of nail psoriasis patients in a study from a pool of plaque psoriasis patients than the NAPSI," the authors write. "Another advantage of the use of the N-NAIL as a scoring tool is that it only has one version, so no confusion exists about the utilization of the exact scoring tool, and it is easier and faster to apply for dermatologists, researchers, and other specialists working with nail psoriasis compared to other scoring systems."
Several authors disclosed ties to the pharmaceutical industry.
International Journal of Dermatology