Assessment of the validity of HLD (CalMod) in identifying orthodontic treatment need.

Objective: The purpose of this study was to assess the validity of the Handicapped Labio-Lingual Deviation index with California modifications, HLD (CalMod), in identifying handicapping malocclusions.

Methods: A set of 153 study casts representing all types of malocclusion was utilized in this study. Models were randomly chosen the UCSF Division of Orthodontics clinic. Treatment need was determined by the HLD (CalMod) index and by a panel of 13 orthodontists, conventionally established as the 'gold standard'. Spearman Rank correlation analysis was used to evaluate the correlation between HLD (CalMod) and the gold standard. The Classification and Regression Tree (CART) modeling was used to determine the HLD (CalMod) cut-off point of orthodontic treatment need according to the gold standard.

Results: A Spearman Rank correlation Coefficient of 0.71 demonstrated a moderately high correlation between HLD (CalMod) and the gold standard. The CART modeling determined a value of 18.5 as the cut-off point of HLD (CalMod) for orthodontic treatment need, considerably lower than the cut-off point of 26 currently used by Medi-Cal. At a value of 26 points as the cut-off HLD (CalMod) displayed a low sensitivity (25.9%) and high specificity (96.8%).With a cut-off point of 18.5, specificity decreased to 55.6% while sensitivity increased dramatically to 92.9%.

Conclusion: Our results show that the HLD (CalMod) with a cut-off point of 26 fails to indentify a considerable percentage of handicapping malocclusions. More studies should be done assessing the efficacy of the HLD (CalMod) in identifying handicapping malocclusion.