BTG3 and systemic lupus erythematosus: More stringent definition of NPSLE and SLE, by respectively excluding the 5 patients with headache and the 6 ANA negative patients at the time of sampling, gave similar results in term of sensitivity (74.2%; 95%CI 55.4% to 88.1%), specificity (46.0%; 95%CI 33.4% to 59.1%), PPV (40.4%; 95%CI 27.6% to 54.2%) and NPV (78.3%; 95%CI 61.8% to 90.2%).