Supplementary Material for: Botulinum toxin underuse in older stroke survivors with spasticity: a nationwide population-based cohort study

Introduction: While botulinum toxin type A (BoNT-A) is effective for poststroke spasticity, its accessibility in older adults remains unclear. We aimed to examine the association between BoNT-A use and age among stroke survivors. Methods: This nationwide, population-based, retrospective cohort study analyzed data from the French National Hospital Discharge Database. Stroke survivors admitted between 2014 and 2016 were followed until 2020. BoNT-A use was assessed across different age groups (18–64, 65–74, 75–84, ≥85 years). Multivariable logistic regression was performed to examine the association between BoNT-A use and age, adjusting for potential confounders, including sex, comorbidities, stroke unit hospitalization, and rehabilitation. Results: BoNT-A use was reported in 1,757 (2.88%), 862 (0.99%), and 183 (0.22%) of 60,928, 86,917, and 82,725 stroke survivors aged 65–74, 75–84, and ≥85 years, respectively. These rates were significantly lower than BoNT-A use in those aged <65 years (5.13%) (p<0.001). After adjustment, the inverse relationship between age and BoNT-A use was maintained, demonstrating an age-dependent association in the 65–74, 75–84, and ≥85 age groups versus 18–64 years. Odds ratios (ORs) (95% confidence intervals [CIs]) were 0.49 (0.47–0.53), 0.18 (0.17–0.19), and 0.05 (0.04–0.06), respectively. Stroke unit stays (OR, 1.33; 95% CI, 1.26–1.41) and neurological rehabilitation unit stays (OR, 16.69; 95% CI, 15.59–17.87) were significantly associated with a higher probability of receiving BoNT-A. Conclusions: BoNT-A use is notably low in older stroke survivors, highlighting the need to enhance equitable access to BoNT-A injections for this population.