Objective: To determine the characteristics of DBS candidates associated with the greatest improvement in HRQL outcomes after surgery.

Background: Site reviews of expert DBS centers have identified differences in the processes of candidate identification and qualification.  It has not been established whether this variation in routine clinical practice is associated with improved outcomes.

Methods: Using data from the National Parkinson Foundation’s Quality Improvement Initiative (NPF-QII), a longitudinal outcomes study of subjects managed in an expert care setting without exclusions, 460 subjects were identified who were recruited into the study before being referred for DBS and were evaluated subsequently.  Post-surgical HRQL was evaluated using the PDQ-39.  Sites were evaluated for outlier status, defined as a site with a significant positive or negative deviation from the pooled data of the other sites, using a two-tailed heteroscedastic Student’s t-Test, considering only sites with at least 25 subjects in the set.  To limit the familywise error rate to p < 0.05, Bonferroni correction set the threshold for significance at p < 0.0057.

Results: Nine of 20 participating centers recruited at least 25 subjects (range: 28-48 subjects).  The mean change in PDQ-39 score after DBS surgery was an -1.8 points versus baseline (SD: 1.3; negative scores represent improvement).  The mean for each center ranged from 2.2 points to -8.2 points (IQR: -0.4 to -2.6).  The center that achieved an average -8.2 point change from baseline represented a significant improvement versus the pooled other sites and was associated with a population whose baseline status differed significantly from the other sites: higher rate of motor fluctuations (93% vs 78%); less frequently reporting comorbidities; better mobility (measured both with the PDQ-39 mobility and timed up-and-go test), and lower falls.  In other demographic and baseline variables, this center’s DBS candidates did not differ from others, with age, disease duration, Hoehn and Yahr stage, and cognition all comparable.

Conclusions: Many factors contribute to optimal patient outcomes and significant further study is necessary to identify causal factors, however these associations with improved outcomes could inform further study.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/baseline-characteristics-associated-with-greatest-improvement-in-hrql-after-dbs-surgery/