Predicting non-response to intraglandular botulinum neurotoxin A injections for drooling in children with neurodevelopmental disabilities

Aim: To develop robust multivariable prediction models for non-response to (1) submandibular botulinum neurotoxin A (BoNT-A) injections and (2) concurrent submandibular and parotid (four-gland) injections, to guide treatment decisions for drooling in children with neurodevelopmental disabilities, including cerebral palsy.Method: This was a retrospective cohort study including 262 children (155 males/107 females, median age 7 years 11 months [IQR 5 years 1 month], range 4 years 0 months - 17 years 11 months) receiving submandibular injections and 74 children (52 males/22 females, median age 7 years 7 months [IQR 4 years 3 months], range 4 years 9 months - 18 years 8 months) receiving four-gland injections. Multivariable logistic regression analyses were used to estimate associations between candidate predictors and non-response 8 weeks after injection.Results: Ninety-six children (37%) were non-responders to submandibular injections, for which developmental age was the strongest predictor (adjusted odds ratio [aOR] 2.13; 95% confidence interval [CI] 1.02-4.45 for developmental age <4 years or 4-6 years with IQ <70). Other characteristics that showed a trend towards an increased risk of non-response were diagnosis, sex, and head position. Thirty-four children (46%) were non-responders to four-gland injections, for which tongue protrusion (aOR 3.10; 95% CI 1.14-8.43) seemed most predictive, whereas multiple preceding submandibular injections (aOR 0.34; 95% CI 0.10-1.16) showed a trend towards being protective. Predictors were, however, unstable across different definitions of non-response and both models (i.e. submandibular and four-gland) had insufficient discriminative ability.Interpretation: Potential predictors of non-response to BoNT-A injections were identified. Nevertheless, the developed prediction models seemed inadequate for guidance of treatment decisions. image