Ankylosing spondylitis diagnosis in US patients with back pain: identifying providers involved and factors associated with rheumatology referral delay

Abstract

This study aimed to identify providers involved in diagnosing ankylosing spondylitis (AS) following back pain diagnosis in the USA and to identify factors leading to the delay in rheumatology referrals. The Truven Health MarketScan® US Commercial Database was searched for patients aged 18-64 years with back pain diagnosis in a non-rheumatology setting followed by AS diagnosis in any setting during January 2000-December 2012. Patients with a rheumatologist visit on or before AS diagnosis were considered referred. Cox regression was used to determine factors associated with referral time after adjusting for age, sex, comorbidities, physician specialty, drug therapy, and imaging procedures. Of 3336 patients included, 1244 (37 %) were referred to and diagnosed by rheumatologists; the others were diagnosed in primary care (25.7 %), chiropractic/physical therapy (7 %), orthopedic surgery (3.8 %), pain clinic (3.6 %), acute care (3.4 %), and other (19.2 %) settings. Median time from back pain diagnosis to rheumatology referral was 307 days and from first rheumatologist visit to AS diagnosis was 28 days. Referred patients were more likely to be younger (hazard ratio [HR] = 0.986; p < 0.0001), male (HR = 1.15; p = 0.0163), diagnosed with uveitis (HR = 1.49; p = 0.0050), referred by primary care physicians (HR = 1.96; p < 0.0001), prescribed non-steroidal anti-inflammatory drugs (HR = 1.55; p < 0.0001), disease-modifying antirheumatic drugs (HR = 1.33; p < 0.0001), and tumor necrosis factor inhibitors (HR = 1.40; p = 0.0036), and to have had spinal/pelvic X-ray prior to referral (HR = 1.28; p = 0.0003). During 2000-2012, most patients with AS were diagnosed outside of rheumatology practices. The delay before referral to rheumatology was 10 months; AS diagnosis generally followed within a month. Earlier referral of patients with AS signs and symptoms may lead to more timely diagnosis and appropriate treatment.

Keywords: Ankylosing spondylitis; Anti-TNF; Diagnostic delay; Referral strategies; Treatment patterns.

Fig. 1

Study design and patient selection. An overview of the study design is shown in panel a. The follow-up period (i.e., the period of time from back pain diagnosis to AS diagnosis) is outlined in red. Patient flow is depicted in panel b. Populations included and excluded from the main analysis are depicted by the blue and gray boxes, respectively. The orange boxes depict a patient population that was excluded from the main analysis owing to primary diagnosis by a non-rheumatologist but who had their diagnosis subsequently confirmed by a rheumatologist. AS = ankylosing spondylitis; CD = Crohn’s disease; HMO = health maintenance organization; PsA = psoriatic arthritis; PsO = psoriasis; RA = rheumatoid arthritis; UC = ulcerative colitis. ^aPatients with no interruption in insurance status

Fig. 2

Diagnosis of AS by physician specialty. “Others” consists of any provider not specified as rheumatologist, primary care provider (PCP), chiropractor/physical therapist (PT), orthopedist, pain management, or acute care specialist or where provider specialty was missing. AS = ankylosing spondylitis

Fig. 3

Patterns of prescription drug use (a) and imaging procedures (b) by referred and non-referred patients. CT = computed tomography; DMARD = disease-modifying antirheumatic drug; MRI = magnetic resonance imaging; NSAID = non-steroidal anti-inflammatory drug; TNF = tumor necrosis factor