Background: Axial spondyloarthritis (axSpA) takes two forms – radiographic (also known as ankylosing spondylitis(AS)) and non-radiographic (nr-axSpA). The symptoms caused are similar with chronic back pain, but nr-axSpA damage cannot be seen on X-rays. Historically, nonradiographic axial spondyloarthritis (nr-axSpA) did not have any approved codes so clinicians had to use AS and other codes. Starting in FY 2020, it was indexed into M46.8 – other specified inflammatory spondylopathies, but that did not allow it to be teased out from other inflammatory conditions. However, starting in FY 2022, has its own sub-category, M45.A. From a research perspective, this enables nr-axSpA patients to be separated from other patients to see their clinical presentation and care.
Methods: The Vizient™ Clinical Data Base administrative claims database was queried for admissions with ICD-10-CM codes for nr-axSpA (M45.A*), other specified inflammatory spondylopathies (M46.8*) and AS (M45* except for M45.A) during fiscal years 2020 to 2022.
Results: In FY 2022 there were only 26 admissions for patients with nr-axSpA compared to 1192 for patients with other specified inflammatory spondylopathies in the two previous years. Between FY 2020 and 2022 there were 25,102 inpatient admissions with a diagnosis of AS. As outlined in literature, the nr-axSpA cohort was more female (69.2%) compared to 52.0% female in the other cohort and 37.0% female in the AS cohort. The racial/ethnic composition of the nr-axSpA group had more non-Hispanic black patients (15.4%) compared to the other cohort (12.7%) and the AS cohort (8.3%). Similarly, there were fewer non-Hispanic white patients (65.4%) than the other (70.0%) and AS (75.6%) cohorts. The average age of nr-axSpA patients was 52.2 years compared to 66.0 years for the other cohort and 61.2 years for the AS cohort. Corresponding to younger age for patients, there were fewer Medicare patients (26.9%) in the nr-axSpA cohort compared to the other (59.0%) and AS (55.1%) cohorts. The average LOS for the nr-axSpA was shorter, with an average of 4.8 days compared to 6.3 days for the other group and 7.0 days for the AS cohort.
Conclusions: The creation of a distinct ICD-10 code for nr-axSpA can lead to opportunities to better research and identify the needs of this population. It is evident this cohort has different characteristics than the broader other specified inflammatory spondylopathies group – more female, more non-Hispanic black, shorter LOS, younger average age, fewer Medicare patients. It may take more time in order for more knowledge and coding of this group and this disease to take place to build administrative claims that can be leveraged for further research.