Multiple sclerosis national registry system in Iran: Validity and reliability of a minimum data set

•The S-CVI values of the relevance, clarity, and simplicity for the whole form were 0.92, 0.96, and 0.93, respectively.•The presented minimum data set had a significantly high content validity in terms of relevance, clarity, and simplicity.•The Persian version of minimum data set found to be valid and reliable in national MS registry system of Iran. As the prevalence and incidence of Multiple Sclerosis (MS) are increasing remarkably in Iran, gathering standardized information regarding the individual's diagnosis, care, and outcomes through a uniform registry system would enable policy-makers to systematically plan for care quality improvements. To design a valid and reliable Persian version of a minimum data set to be utilized and integrated into the national MS registry system of Iran. The minimum data set consisted of six domains including patient identification, family history of MS, diagnosis, disease course, disability status, and medications. The content validity was assessed based on 27 experts’ opinions. Item-Content Validity Index (I-CVI) and Scale-Content Validity Index (S-CVI) were used to assess the questions and their validities. Reliability was evaluated using the intra-class correlation coefficient (ICC) of the test-retest results. For validity appraisal, 27 experts reviewed the developed minimum data set. All the items had I-CVI values higher than the critical value of 0.78 in terms of relevance, clarity, and simplicity, except for “medication start date” and “medication end date” in relevance (I-CVI = 0.75 and 0.73, respectively) and “MS type” in simplicity (I-CVI = 0.76). The total S-CVI scores for relevance, clarity, and simplicity were higher than 0.9. In reliability assessment, 27 patients (out of 74 interviewed patients) were re-interviewed to assess the test-retest reliability. All ICCs were higher than the critical value of 0.7 (in 14 items out of 16), except for “progression to secondary-progressive MS” with the ICC = 0.68 and “the reason for medication discontinuance” with the ICC = 0.64. The use of standardized validated minimum data set has the potential to enable the researchers and policy-makers to systematically compare and analyze patient information. The Persian version of the minimum data set found to be valid and reliable in Iran.