The Adult Deformity Surgery Complexity Index (ADSCI): a Valid Tool to Quantify the Complexity of Posterior Adult Spinal Deformity Surgery and Predict Postoperative Complications

Publication date: Available online 4 July 2017
Source:The Spine Journal
Author(s): Ferran Pellisé, Alba Vila-Casademunt, Susana Núñez-Pereira, Montse Domingo-Sàbat, Juan Bagó, Xavier Vidal, Ahmet Alanay, Emre Acaroglu, Frank Kleinstück, Ibrahim Obeid, Francisco J S Pérez-Grueso, Virginie Lafage, Shay Bess, Christopher Ames, Anne F. Mannion
Background ContextIn 2008, Mirza et al. designed and validated the first and only index capable of quantifying the complexity of spine surgery. However, this index is not fully applicable to adult spinal deformity (ASD) surgery, since it does not include the surgical techniques most commonly used and most strongly associated with perioperative complications in ASD patients.PurposeThe objective of this study is to develop an "Adult Deformity Surgery Complexity Index" (ADSCI), to quantify objectively the complexity of the ASD posterior surgery.Study Design/SettingExpert consensus (Delphi process) and retrospective analysis of prospectively collected data using multiple regression models.Patient SamplePatients prospectively enrolled in two comparable multicentric ASD databases sharing same inclusion criteria.Outcome MeasuresInternal and external validation of ADSCI using R² for intraoperative bleeding and length of surgery. Receiver Operating Characteristics (ROC) and Area Under the Curve (AUC) analysis to assess ADSCI sensitivity and specificity.MethodsADSCI development and validation was based on the construction and comparison of three different tools: ADSCI score constructed by three rounds of expert consensus (ADSCI-Delphi) and two multiple regression models (ADSCI-RM-Simple and ADSCI-RM-Mixed). Their predictive capability was compared by means of R² values in the same subrogated of surgical complexity as in the Mirza index validation: intraoperative bleeding and duration of surgery. Sensitivity and specificity were evaluated using Receiver Operating Characteristics (ROC) curves and area under the curve (AUC) analysis. The external validity was also examined by evaluating its predictive capability in another multicenter ASD database of comparable patients in the USA.ResultsAt the time of the study, the database included 1325 patients. 475 of these were eligible for the study, having been treated surgically using a posterior approach only (52.2y SD20; 77.7% female; 85.4% ASA I/II). 51 international experts participated in the Delphi-consensus process. The surgical variables selected by consensus and included in the equation were divided into actions and factors. Actions selected were: number of fused segments, decompressions, interbody fusions and cemented levels; number and type of posterior osteotomies and use of pelvic fixation. The factors included were: implant density, revision surgery and team experience. ADSCI-RM-Mixed (Regression model with Delphi formula interactions), provided the best estimates and predictive value, well above Mirza's invasiveness index. The ADSCI-RM-Mixed, with greater AUCs (>0.70), was also the most sensitive and specific for both of the dependent variables studied and for complications prediction. ADSCI-RM-Mixed obtained also the highest R² values in the validation cohort in predicting blood loss (R²=0.34) and surgical time (R²=0.26) with similar effect sizes to those for the derivation cohort.ConclusionsADSCI is the first tool to be specifically developed for the preoperative assessment of the complexity of ASD surgery. This study confirms its validity, specificity and sensitivity and shows it has greater predictive capability than the more generic Mirza invasiveness index. ADSCI should be useful for quantitatively estimating the increased risk associated with more invasive surgery and adjusting for surgical case-mix when making safety comparisons in ASDS.



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