Epidemiology of Transthyretin Familial Amyloid Polyneuropathy in Portugal: A Nationwide Study

Background: Transthyretin-associated familial amyloid polyneuropathy (TTR-FAP) is a rare, hereditary, progressive and neurodegenerative disease. We aimed to study -TTR-FAP epidemiology in Portugal.

Methods: National, observational, prospective and retrospective, case identification of adults with TTR-FAP. Countrywide patient multiple identification sources included reference centers registries and centralized medical electronic prescription database. Crude rates were reported per 100,000 adult inhabitants.

Results: Over 2010-2016 period, mean incidence rates was 0.87/100,000 (95% CI 0.68-1.10) corresponding to 71 new patients yearly, that has decreased 31% in the last 7 years. The proportion of late-onset cases (age ≥50 years) among incident cases was 28.7%. Estimated crude 2016 prevalence was 22.93/100,000 adult inhabitants (95% CI 21.90-23.99) corresponding to 1,865 TTR-FAP individuals in Portugal (45.8% male; mean age: 52.3 ± 15.4 years). In 2016, the Portuguese region with the highest TTR-FAP prevalence shows a 16% prevalence increase over the last 25 years.

Conclusions: In Portugal, TTR-FAP affects both genders and mainly young adults. TTR-FAP incidence appears to be decreasing while prevalence is increasing. In comparison to previous studies, there is an increased representativeness of late-onset patients. This epidemiological setting poses future and complex challenges for the social and healthcare system, strengthening the relevance of regular epidemiologic surveillance.