RESUMO
BACKGROUND: The purpose of this study was to assess the validity and reliability of Handicapping Labio-Lingual Deviation index (HLDI) scoring methods as calculated by digital models (DM) and visual inspection (VI) and their agreement to either meet or fail to meet the Medicaid coverage threshold. An additional objective was to assess the agreement with Medicaid managed care organizations (MCO) coverage decisions. METHODS: The study included the orthodontic records of 401 patients who applied for Medicaid coverage. Two methods were used to calculate HLDI scores: (1) Measurements derived from DMs using OrthoCAD software; and (2) VI of intraoral photographs. The levels of agreement between the two methods and the Medicaid coverage decision by a MCO were evaluated. RESULTS: The study results show a high level of agreement between the two HLDI calculation methods, DM and VI evaluation methods(Cramer's V = 0.812). The agreement on coverage decisions (eligible/not eligible) between VI methods and the official MCO decision was Cramer's V = 0.318. The agreement on coverage decisions between the DM method and the official MCO decision was Cramer's V = 0.318. CONCLUSIONS: MCO assessment results of the patients using HLDI showed low agreement with the results obtained by DM and VI scoring methods used in this study. The Illinois Medicaid system is apparently using unknown factors other than the HLDI score when determining when approving or disapproving orthodontic coverage. PRACTICAL IMPLICATIONS: MCO decisions on eligibility for orthodontic treatment coverage were not consistent with patients' treatment needs.