Neuromyelitis optica spectrum disorders registry system in Iran: Validity of data sets

•The national registry system in Iran (NMORI) is based on the previous experiences of international NMOSD registries in collecting patients' information.•The presented minimum data set had a significantly high content validity in terms of relevance, transparency and simplicity.•The Persian version of minimum data set found to be valid in NMORI. A targeted structure for recording, monitoring, and follow-up of patients with neuromyelitis optica spectrum disorders (NMOSD) is in demand. To obtain the correct and uniform standardized information registry system, it is necessary to use a data set that has good validity to help policy-makers systematically plan for improvements in the quality of care. The main goal of the present study was to develop a NMOSD data set for the national registry system in Iran (NMORI) and to evaluate the validity of the presented data set. The NMORI data set consisted of baseline characteristics, disease and exposure history, background and past medical history, diagnosis and treatment, clinical features, imaging, and para-clinical findings. The content validity was evaluated by 18 experts from Iran, Japan, and Denmark by scoring each of the questionnaire items in term of transparency, simplicity, and relevance. According to the points given, the content validity index (CVI) and content validity ratio (CVR) scores were calculated and compared with the critical limit. The current study was designed as a 125-items data set which was considered valid. In terms of relevance 110 out of 125 items, simplicity 113 out of 125 items, and transparency 123 out of 125 items had Item-CVI>0.79. All Scale-level-CVI values were greater than 0.9, showing noticeable content validity. In this data set, 112 items had CVR > 0.49, which was considered an acceptable level of significance. The implementing of NMORI is important in a developing country such as Iran with significant increasing prevalence of this disease. This registry facilitates a uniform and valid diagnosis and is considered valid for clinical investigation and epidemiological research on NMOSD. Scientists and healthcare policymakers can rely on a validated data set in order to have access to accurate data.