Does the Kushida morphometric model predict outcomes following maxillomandibular advancement surgery for obstructive sleep apnoea?

[OBJECTIVE] The primary aim of this study was to explore the predictive potential of the preoperative Kushida index score and subsequent outcome following maxillomandibular advancement surgery (MMA). Secondarily we looked at how well the Kushida values of our OSA patients matched the morphometric models diagnostic thresholds.

[METHODS] We performed a retrospective analysis of patients who underwent MMA for OSA at our institution. Kushida morphometric scores were calculated using the described formula: P + (Mx - Mn) + 3 × OJ + 3 × [Max (BMI - 25)] × (NC ÷ BMI). Regression analysis was performed to explore the possible association between Kushida index score and outcome variables of postoperative apnoea/hypopnea indices (AHI) and Epworth Sleepiness Scores (ESS).

[RESULTS] We identified 28 patients with complete data available for analysis. The mean age was 45 years (SD 6) with mean BMI of 28 (SD 3). All, but one patient underwent bi-maxillary procedure with or without genioplasty, with a mean advancement of 8.5 mm (SD 2). The mean Kushida index score in our sample was 79 (SD 14). 89% of patients had postoperative AHI <15 in keeping with surgical success. We found no statistically significant relationship with Kushida morphometric model variables and overall score with either of our outcome variables.

[CONCLUSION] The mean Kushida index score in our patients was in the range consistent with the morphometric models diagnostic cut-off for OSA. Kushida's morphometric model does not appear to be a good predictor of postoperative success in individuals following MMA. The morphometric model represents a clinical adjunct in the initial diagnostic work-up of OSA patients referred for surgery.