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Occurrence and Mortality of Stiff Person Syndrome in Denmark
Henrik Toft Sørensen1, Trine Toft Sørensen2, Holly Elser3,4
1Department of Clinical Epidemiology and Center for Population Medicine, Aarhus University and Aarhus University Hospital, Aarhus, Denmark, hts@clin.au.dk.
Introduction:
Stiff person syndrome is a rare and progressive neurological disorder, yet evidence on long-term outcomes is limited. We examined the occurrence and mortality associated with stiff person syndrome in Denmark.
Methods:
We conducted a population-based cohort study including all Danish citizens from 2001 to 2022. Individuals with a first-time diagnosis of stiff person syndrome (N = 30) were identified in the Danish National Patient Registry covering all Danish hospitals and matched 1:100 on sex and birth year with persons from the general population (N = 3,000). Incidence, prevalence, cumulative mortality, and mortality rates were estimated, and Cox proportional hazards regression was used to compute hazard ratios (HRs) as an estimate of mortality rate ratios adjusted for sex, year of birth, and comorbidity with 95% confidence intervals (CIs).
Results:
Thirty patients were diagnosed during the study period; 53.3% were male, and median age at diagnosis was 50 years. Incidence increased from 0.11 per 1,000,000 person-years (2001-2008) to 0.43 (2017-2022). Prevalence rose from 1.32 per 1,000,000 in 2016 to 3.94 in 2022. The 10-year cumulative mortality in the stiff person syndrome cohort was 27.5% (95% CI: 13.8-50.1) (HR = 4.1 [95% CI: 1.9-8.9).
Conclusion:
Stiff person syndrome is a rare disorder with increasing incidence and prevalence and high mortality.
