Validating the Handicapping Labiolingual Deviation Index in Determining Orthodontic Treatment Need

Abstract

Introduction: The purpose of the study was to assess the agreement between the Handicapping Labiolingual Deviation (HLD) Index and MassHealth orthodontic coverage decisions in order to discern whether discrepancies exist in the current screening process in the state of Massachusetts. Methods: This study consisted of a retrospective chart review including 57 patients at the Harvard School of Dental Medicine. Subjects were divided into two subgroups, those approved (n=31) for comprehensive orthodontic treatment and those denied (n=26) by MassHealth insurance. The HLD form submitted by the treating orthodontic resident was extracted from the MassHealth submission log. Using the iTero scan taken at the initial consultation, OrthoCAD software was then utilized to re-score the subjects according to the American Board of Orthodontics Discrepancy Index (DI). The DI score was then compared to the HLD score for each subject. In addition, the HLD score was compared to the ultimate approval or denial decision by MassHealth to assess agreement between the treating provider and the MassHealth reviewers. Results: To assess the agreement between HLD score and the MassHealth decision, a T-test was conducted. Approved cases had significantly higher HLD scores (mean=23.81, SD=7.00) than denied cases (mean=17.42, SD=7.11), with a mean difference of 6.38 points (p=0.001, 95% CI: 2.63–10.14). To compare the HLD Index and ABO Discrepancy Index, Pearson correlation was conducted, and normality of both variables was confirmed by the Shapiro-Wilk test. The two indices shared less than 9% of common variance (r².09), indicating very limited agreement. Among subjects submitted with an autoqualifier, the majority (77.8%) were approved (n=28), whereas only 22.2% were denied (n=8). The most commonly identified autoqualifier condition was an impinging overbite, observed in 14.04% (n=8) of cases. Both medical necessity letter submission (OR=10.20, 95% CI: 1.98-52.55, p=0.005) and HLD score (OR=1.20 per point, 95% CI: 1.07-1.34, p=0.002) were significant independent predictors of MassHealth approval. These associations remained significant in the multivariable model adjusting for malocclusion type, age group, and gender. Conclusion: Despite overall agreement between the HLD Index and MassHealth outcomes, the data reflects a discrepancy in cases that were submitted with an autoqualifier but ultimately denied comprehensive coverage for orthodontic treatment, suggesting that additional records (model composite, occlusogram) may serve as useful diagnostic aids, particularly in cases with deep impinging bite. Moreover, submitting a medical necessity letter was found to be a significant independent predictor of MassHealth approval, nearly doubling approval rates, and therefore treating providers should be encouraged to submit these on behalf of all patients.