Diagnostic criteria for neuropsychiatric systemic lupus erythematosus: the results of a consensus meeting. The Ad Hoc Neuropsychiatric Lupus Workshop Group. Definitions and classifications proposed for the neuropsychiatric complications of systemic lupus erythematosus (NP-SLE) indicate a wide range of approaches taken by different researchers and clinicians. A meeting of investigators was convened to begin a consensus process for standardizing its classification. We found that the level of agreement among raters on the importance of elements to the diagnosis of NP-SLE increased significantly as indicated by an intraclass correlation coefficient of 0.05 before the conference to 0.60 after the conference. The results of such studies can be used to generate and test the utility of diagnostic criteria for NP-SLE in multicenter trials. 