Validation of the provisional seven-item criteria for the diagnosis of polyarteritis nodosa

The 1990 American College of Rheumatology (ACR) criteria for the classification of polyarteritis nodosa (PAN) have many pitfalls and performed poorly when used for diagnostic purposes. Recently, a provisional seven-item diagnostic criteria for PAN was proposed. To validate the provisional seven-item diagnostic criteria for PAN in a cohort of PAN patients from a tertiary care centre in India. Clinical details of patients diagnosed as PAN as per the European Medicines Agency algorithm between 2005 and 2020 were collected retrospectively. Age and sex-matched anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV) patients were included in the non-PAN group. Patients with a deficiency of adenosine deaminase 2 (DADA2) were included as a separate group. The sensitivity, specificity, positive and negative predictive values (PPV and NPV) for ACR criteria, the Ministry of Health, Labour and Welfare (MHLW) in Japan diagnostic criteria and the seven-item diagnostic criteria were calculated. Thirty-seven PAN, 14 DADA2 and 37 AAV patients were included in the analysis. The sensitivity, specificity, PPV and NPV of the seven-item criteria were 83.7%, 96.8%, 97.3% and 81.1% respectively. For the ACR criteria, sensitivity was 82.9% and specificity was 79.5%. The sensitivity, specificity for MHLW criteria were 77.3% and 90% respectively. The sensitivity and specificity of seven-item criteria for DADA2 patients were 58.8% and 88.2% respectively. There was very poor agreement between the ACR criteria and the seven-item and MHLW criteria and fair agreement between seven-item and MHLW criteria (κ = 0.279). The provisional seven-item criteria for PAN performed well with high specificity and PPV.