Background Ankylosing spondylitis (AS), a chronic rheumatic disease predominantly involving the axial skeleton, can substantially impact work productivity in employed patients, resulting in economic costs to employers and society.1,2
Objectives To assess salary growth, an integrated measure of work performance, in employed patients with AS treated with and without anti-TNF therapy.
Methods Adult employees (18 – 64 years old) with at least one diagnosis of AS (ICD-9-CM: 720.0) were identified from a large-scale US employer claims database (covering individuals from 82 self-insured Fortune 500 companies, 2003Q3-2013Q1). Patients were divided into two cohorts: the anti-TNF cohort (receiving adalimumab, etanercept, golimumab, or infliximab) and the non-anti-TNF cohort. Annual salary growth rates were studied from the index date (anti-TNF initiation or a randomly selected date of a non-TNF systemic prescription for the non-anti-TNF cohort). Eligible patients were followed until the end of data availability up to 5 years. Salary growth by cohort was assessed using a longitudinal regression model adjusting for baseline characteristics. Adjusted annual salary growth rates for the two cohorts were used to predict the 5-year cumulative salary difference assuming an average wage of the US general employed population ($43,212/year; 2007-2011).
Results 223 and 419 actively employed AS patients were eligible to be included in the anti-TNF and the non-anti-TNF cohorts, respectively. Patients in the anti-TNF cohort were younger than those in the non-anti-TNF cohort (41.4 vs. 46.8 years, p<0.001) and more likely to be males (74.9% vs. 66.3%, p=0.026). Mean baseline salary was significantly lower in the anti-TNF cohort ($62,868 vs. $75,665, p=0.014). More patients in the anti-TNF cohort had medical claims for inflammatory comorbidities (psoriatic arthritis: 11.2% vs. 1.9%; rheumatoid arthritis: 14.8% vs. 9.1%; psoriasis: 7.2% vs. 1.2%, all p<0.05), and medical claims for mechanical low back problems (26.9% vs. 18.1%, p=0.01). After adjusting for baseline characteristics, AS patients in the anti-TNF cohort had a significantly higher annual salary growth rate compared to patients in the non-anti-TNF cohort (5.04% vs. 3.35%, p=0.005), resulting in a higher cumulative 5-year salary growth of 27.8% vs. 17.9%. This would result in a cumulative 5-year salary gain of $12,233 for an average employee with AS who is receiving anti-TNF systemic therapy (Figure).
Conclusions Compared to treating with non-anti-TNF systemic agents, anti-TNF treatments were associated with a significantly higher salary growth rate among employees with AS. Given that AS predominantly affects patients in their productive years, effective treatment can mitigate the economic burden of AS for employees as well as employers.
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Disclosure of Interest A. Deodhar Grant/research support from: AbbVie, Amgen, Janssen, Novartis, Pfizer, UCB, Consultant for: AbbVie, Amgen, Janssen, Novartis, Pfizer, UCB, M. Mittal Shareholder of: AbbVie, Inc., Employee of: AbbVie, Inc., A. Joshi Shareholder of: AbbVie, Inc., Employee of: AbbVie, Inc., J. Signorovitch Consultant for: AbbVie, Inc., Employee of: Analysis Group, Inc., M. Yang Consultant for: AbbVie, Inc., Employee of: Analysis Group, Inc., Y. Bao Shareholder of: AbbVie, Inc., Employee of: AbbVie, Inc.