Introduction: There are currently no population-based studies that investigate whether neurofibromatosis type 1 (NF1) is an independent risk factor for stroke. Due to the evidence for an NF1-related vasculopathy and the higher prevalence of cerebrovascular anomalies in this population, we hypothesized that there would be a positive association between NF1 and stroke.
Methods: We designed a case-control study using the Nationwide Inpatient Sample (NIS), a nationally representative sample of US inpatients, to compare the odds of stroke in patients with and without NF1. We used multivariable logistic regression to adjust for potential confounders such as diabetes, hypertension, atherosclerosis, atrial fibrillation, and Moyamoya disease.
Results: Among over 85 million admissions between 1998 and 2009, we identified 21,378 (0.02%) with NF1, corresponding to the prevalence in the general non-hospitalized population. NF1 was associated with younger mean age (41 vs. 48) and a lower prevalence of common stroke risk factors. However, pediatric NF1 was more likely to be associated with hypertension. Hospitalized patients with NF1 were significantly more likely to be diagnosed with stroke (OR 1.2, p<0.0001) compared to the general population, primarily due to non-traumatic intracranial hemorrhage (ICH) (OR 1.9, p<0.0001). In the pediatric population, the odds of ICH were more dramatically elevated (OR 8.1, p<0.0001). The odds of ischemic stroke were also increased with NF1 in the pediatric population (OR 3.4, p<0.0001) but not in the adult population.
Conclusions: Stroke is more common in hospitalized patients with NF1, possibly due to a higher risk of cerebrovascular pathology and an inherent vasculopathy. This is particularly true for the pediatric population. The excess risk appears to arise mostly from hemorrhagic etiologies, although the prevalence of ischemic stroke is also higher in the pediatric NF1 population. Physicians caring for patients with NF1 should be aware of the potential for enhanced stroke risk.
Patient Care: We present evidence that patients with NF1 have a higher risk of ischemic and hemorrhagic strokes, possibly due to an inherent underlying vasculopathy or to an increased prevalence of cerebrovascular anomalies. Increasing physician awareness of this potential for risk may lead to more efficient screening and stroke prevention in this patient population.
Learning Objectives: 1. To demonstrate that adults and children with NF1 may be at a higher risk of stroke.
2. To demonstrate how administrative databases can be used to address challenging clinical questions.