Epidemiology of Light-Chain Amyloidosis: A Population-Based Cohort Study in Taiwan

Introduction: AL (light-chain) amyloidosis is a rare disease with an incidence rate of approximately 12-13 per million population in Western countries. To date, the epidemiology of AL amyloidosis in Asian countries has not been described. Population-based clinical information about AL amyloidosis is needed to understand disease characteristics and the impacts of future treatments on the disease

Methods: We conducted a retrospective cohort study using the Taiwan National Healthcare Insurance Research database (NHIRD) and Death Registry to estimate the incidence, prevalence, all-cause mortality rate and characteristics of patients with AL amyloidosis in Taiwan. All patients with confirmed newly diagnosed AL amyloidosis (ICD-10 E85.4: Organ-limited amyloidosis, E85.8: Other amyloidosis and E85.9: Amyloidosis, unspecified) from 01 January 2016 until 31 December 2019 were enrolled. Eligible patients had a biopsy record within 12 months prior to, or up to 6 months after the date of diagnosis of AL amyloidosis; and at least two consecutive outpatient claims and/or one inpatient claim amyloidosis in the NHIRD. Patients were followed up until dis-enrolment, death or study end (31 December 2019), whichever occurred first.

Results: A total of 841 patients with newly diagnosed AL amyloidosis were identified in Taiwan during the period 01 January 2016 until 31 December 2019. The median age at diagnosis was 61.4 years and 58.7% were men. At diagnosis, cardiac disease was present in 28.54%, renal-related disease in 23.19% and had 7.85% had multiple myeloma (Table).

The crude annual incidence of AL amyloidosis was 8.46 per million population in 2016 and 8.31 per million population in 2019 (Figure). The age-adjusted incidence rates were 5.73 and 5.26 per million population, respectively. The crude and age-adjusted prevalence rates of AL amyloidosis remained similar over the study period: the crude prevalence rates were 121 to 142 per million population, and age-adjusted prevalence rate were 81.52 to 99.84 per million population. The all-cause mortality rate ranged from 1.7 to 2.9 per 1000 patients over the study period but was highest (~10 per 1000) in patients aged ≥80 years. There were 501 patients (59.6%) with a biopsy report prior to the AL diagnosis index date. Presenting clinical symptoms were not available in the claims database so we assessed the time period from biopsy to diagnosis. The median time from biopsy until diagnosis was 3.8 months and was longer than 12 months in some patients, with little change observed from year to year.

Conclusion: To our knowledge, this is the first known population-based cohort study of non-hereditary amyloidosis in Asia. The incidence of AL amyloidosis in Taiwan appears to be similar to Western countries with higher prevalence in Asia. There was no apparent change in the incidence or prevalence rates over the 4 years of the study. Diagnostic delay is recognized as an important limitation in the treatment of AL amyloidosis.

Figure 1

View largeDownload slide

Figure 1

View largeDownload slide

Close modal