Validation and Reliability of the Portuguese Version of the Michigan Neuropathy Screening Instrument.

BACKGROUND: Diabetic peripheral neuropathy is very common in the diabetic population. Early screening for foot pathology is of the utmost importance. The Michigan Neuropathy Screening Instrument (MNSI) is an easy, brief, and noninvasive screening tool. The aim of this study was to validate the semantics and characteristics of both sections of the Portuguese translation of the MNSI for Portuguese diabetic patients.

METHODS: A cross-sectional study was performed on 87 type 1 and 2 diabetic patients at our outpatient endocrinology department. The final sample was composed of 76 patients. Nerve conduction studies were requested, but only a subsample of 42 patients agreed to participate in them.

RESULTS: The scale was internally consistent (Cronbach's alpha > 0.70 in section A, or a clinical history questionnaire and a physical examination [section B]), and the scores of both sections were positively correlated (r = 0.70; P < 0.001). With regard to stability, MNSI scores between test/retest showed high stability (intraclass correlation coefficient = 0.91). The receiver-operating characteristic (ROC) demonstrated its validity, with ROC curve values for section A, section B, and sections A + B of 0.913, 0.798, and 0.906 respectively. Considering a cut off of ≥ 3 in section A and of ≥ 2 in section B, we obtained a sensitivity of 100% and 86%; a specificity of 64% and 61%; a positive predictive value of 80% and 73%; and a negative predictive value of 100% and 79%, respectively.

CONCLUSIONS: The Portuguese MNSI is a reliable and valid tool for screening diabetic neuropathy.