Study Estimates Prevalence of PSP, Highlights Suggestive Symptoms Prior to Diagnosis

Real-world data have allowed researchers to estimate the age-adjusted prevalence of progressive supranuclear palsy (PSP), a rare neurodegenerative movement disorder. The analysis of insurance databases throughout the United States estimated a prevalence of 2.95 cases per 100,000 population.

According to the researchers, the prevalence of PSP identified by their study—based on 560 PSP cases among more than 38 million patients within the databases—is consistent with, but on the lower end, of previously reported estimates.

These findings appeared recently in Frontiers in Neurology.

“The prevalence of PSP reported in prior studies ranges from 1.39 to 17.3 per 100,000 persons, with a prevalence of [approximately] 6 per 100,000 in Europe. However, most reports of incidence and prevalence have been from clinical records or regional studies in Europe and Japan,” explained the researchers. “Only 1 study, published in 1988, estimated the prevalence in the United States at 1.39 per 100,000; 50 PSP patients were identified based on a survey of neurologists and chronic care facilities in 2 New Jersey counties.”

The researchers noted that disease symptoms often precluded the first PSP-related claim date, which may suggest a delay in the time to diagnosis. Potential symptoms of disease included fractures, falls, and dysarthria, all of which were significantly more common in the patients with PSP compared with the 1200 controls also included in the study.

Within 5 years prior to this index date, the most common diagnoses included gait abnormalities (79.3%), joint pain (54.9%), Parkinson disease (54.6%), fatigue (49.8%), and cerebrovascular disease (45.6%).

“Although such claims were not based on a validated case definition for cerebrovascular disease, and could also represent a workup for stroke based on presentation of PSP and/or falls, the association of PSP with potential stroke before diagnosis is a relatively new finding that may warrant further research,” wrote the researchers. “It is unknown if the identification of diagnostic codes for cerebrovascular disease in this study is indicative of actual diagnoses for cerebrovascular disease or, given that cerebrovascular disease is common and often used as a generic term in patients with vascular spots observed by magnetic resonance imaging, it may not indicate an actual cerebrovascular disease diagnosis.”

Similar to potential disease-related symptoms, all of these common diagnoses were more prevalent among patients with PSP than among controls. Compiling these diagnoses, say the researchers, may prove useful for future predictive models of PSP and may guide a better understanding of the difficulties of diagnosing the disease.

Reference

Viscidi E, Litvan I, Dam T, et al. Clinical features of patients with progressive supranuclear palsy in an US insurance claims database. Front Neurol. Published online June 17, 2021. doi: 10.3389/fneur.2021.571800