Medical care of patients with disorders of aromatic amino acid metabolism: a report based on the Polish National Health Fund data records

Introduction
Patients with disorders of aromatic amino acid metabolism are a heterogeneous group. They vary in morbidity and medical care requirements. Polish newborn screening program allows for quick diagnosis of some inborn errors of metabolism (such as classical phenylketonuria, mild hyperphenylalaninemias, tyrosinemia type 1 and tyrosinemia type 2) and subsequent immediate treatment.

The aim of the study
To evaluate the effect of the Polish public healthcare system in terms of management and access to health care services for children and adults with disorders of aromatic amino acid metabolism.

Material and methods
The analysis was based on the National Health Fund (NFZ) reporting data for 2009-2015. The analysis included patients with disorders of aromatic amino acid metabolism converting ICD-10 coding according to the International Classification of Diseases. The analysis covered patients with codes E70, E70.0, E70.1, E70.2, E70.3, E70.8, E70.9. The analysis was prepared as part of the mapping of health needs in metabolic diseases, http://www.mapypotrzebzdrowotnych.mz.gov.pl/.

Results
In 2009-2015, 4090 patients with disorders of aromatic amino acid metabolism were registered in the NFZ system. The largest number of patients were hospitalized and registered in outpatient specialistic care (AOS) in the first year of life. After the second year of life, the number of hospitalized patients was almost zero, and the number of children (< 18 years) with AOS according to age was stable. After the 18 years of age the number of patients in the AOS gradually decreased. The population of patients aged 0-28 years accounted for 99% of all cases, after 28 years of age were only one percent of the total population. There were 95 deaths, the average age of death was 77 years. In the whole study group the highest number of deaths was recorded after 70 years of age, 21% of all deaths were reported in both working-age patients children (2 deaths). Patients with classical phenylketonuria were the most commonly reported in the AOS. 22% of patients were coded with ICD-10 as E70 without extension.

Conclusions
Children aged 0-18 years with disorders of amino acid metabolism had full access to a well-organized specialized medical care system in Poland. In contrast, care for adult patients with the disorders was limited. It is necessary to properly code the disease using ICD-10 extension codes in order to avoid inconsistency in data reporting or misdiagnosis.