Background/Purpose: This study aimed to analyze the prevalence rates and treatment patterns of male and female ankylosing spondylitis (AS) patients in the United States (US) adult insured population from 2006 to 2016.

Methods: Trends in AS prevalence were calculated for the 10-year period covering January 1, 2006 to December 31, 2016. Adult (18+ years old) AS patients were included in this retrospective analysis of medical and pharmacy claims data from the Truven Marketscan Commercial, Medicaid and Medicare-Supplemental Claims database. Prevalence was determined using two AS definitions; A) ≥2 AS diagnostic codes (ICD-9:720.0; ICD-10:M45.x), or B) ≥1 AS diagnostic code by a rheumatologist. Trends in treatment patterns were also analyzed and stratified by gender.

Results:  The AS prevalence ranged from 0.04% to 0.09% from 2006 to 2016. The mean age between 2006 and 2016 ranged from 49.52 -50.00 years. In 2006, approximately 40% of AS patients were female, while in 2016 over 47% of AS patients were female. Rates of use of TNF inhibitors (TNFi) and oral glucocorticoids increased, while NSAIDs and non-biologic DMARDs (sulfasalazine & methotrexate) rates decreased. Opioid use rates were stable (Figure 1). In 2016, males were more likely to be prescribed TNFi, while females were more likely to be prescribed methotrexate, sulfasalazine, NSAIDs, muscle relaxants, anticonvulsants, opioids, and glucocorticoids (Table 2).

Conclusion: The prevalence of AS diagnosis codes more than doubled between 2006 and 2016, but the very low prevalence suggests that AS continues to be underdiagnosed and under-addressed in routine clinical practice. Despite the increase in female AS patients, females were less likely to be prescribed TNF inhibitors compared to male AS patients.

Figure 1. Trends in Treatment Patterns among AS Patients, 2006-2016

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Figure 2. Medication Use among Male and Female AS Patients in 2016

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