Prepared for: Agency for Healthcare Research and Quality (AHRQ) www.ahrq.gov

1. Antinuclear Antibody, Rheumatoid Factor, and Cyclic-Citrullinated Peptide Testing for the Evaluation of Musculoskeletal Complaintsin Children Prepared for: Agency for Healthcare Research and Quality (AHRQ) www.ahrq.gov

2. Outline of Material • Background • Comparative Effectiveness Review (CER) Development • Clinical Questions Addressed by the CER • Report Findings • Conclusion Statements • Gaps in Knowledge • What To Discuss With Your Patients

3. Background: Musculoskeletal Pain • Musculoskeletal (MSK) pain is pain that affects muscles, bones, ligaments, tendons, or nerves. • MSK pain is common in childhood. • Published prevalence estimates range from 2 up to 50 percent. • Assessment is based on patient history and physical examination. Assessment may be complicated by children having difficulty characterizing their symptoms. • The presence of specific clinical characteristics such as morning stiffness, joint swelling, malar rash, and cytopenias may lead to a high suspicion of a pediatric rheumatic condition. Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

4. Background: Causes of Musculoskeletal Pain • Nonrheumatic Causes • Account for nearly all childhood musculoskeletal (MSK) pain. • Generally attributable to sprains, strains, overuse, and normal body growth. • Rheumatic Causes • Rheumatic MSK pain is much less prevalent than nonrheumatic MSK pain. • Generally chronic and requires early diagnosis and treatment to prevent progression and long-term disability. • Rheumatic causes may include juvenile idiopathic arthritis (JIA), pediatric systemic lupus erythematosus (pSLE), spondyloarthropathies (including enthesitis-related arthritis, juvenile ankylosing spondylitis, or reactive arthritis), acute rheumatic fever, or Henoch-Schönlein purpura. Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

5. Background: Juvenile Idiopathic Arthritis • Most common chronic inflammatory disease of children, with a prevalence of 1 per 1,000 children. • Musculoskeletal pain is not universally present in children with JIA. Sixteen percent of children with juvenile idiopathic arthritis (JIA) do not report pain. • Without effective treatment, JIA can progress and cause damage to cartilage, bone, and soft tissues and may lead to severe disability and functional loss and, in rare cases, to organ failure and death. • Early diagnosis and treatment may reduce the progression of the disease and induce remission. • Only a minority of patients will experience complete resolution of JIA symptoms before adulthood. Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

6. Background: Pediatric Systemic Lupus Erythematosus • An episodic, multisystem, autoimmune disease. • Widespread inflammation of blood vessels, connective tissues, and organs. • Estimated incidence of 0.3–0.9 per 100,000 children per year; estimated prevalence of 3.3–8.8 per 100,000 children. • Onset is rare before 5 years of age and uncommon before adolescence. • Left untreated, pediatric systemic lupus erythematosis is often progressive and can be fatal. • Early diagnosis and rapid introduction of effective immunosuppressive treatment have led to improved outcomes. Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

7. Background: Using Serological Tests To Diagnose Musculoskeletal Pain • The diagnosis of inflammatory arthritis is based solely on a patient history and physical examination. • An accurate diagnosis of pediatric musculoskeletal (MSK) pain may be complicated by a nonspecific pain pattern or lack of confidence in the MSK physical examination. • Serological tests such as antinuclear antibody, rheumatoid factor, and cyclic-citrullinated peptide may be ordered when children and adolescents are suspected of having a rheumatic cause for their MSK despite uncertainties about: • their diagnostic performance, • their usefulness, and • their proper interpretation for pediatric populations. Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

8. Background: Antinuclear Antibody Test • Can be used to screen for specific autoimmune conditions, such as systemic lupus erythematosus, Sjögrens syndrome, and systemic sclerosis. • Techniques used for antinuclear antibody (ANA) testing include indirect immunofluorescence (IIF) and enzyme immunoassay (EIA, ELISA). • Neither test has been standardized in children; methods and interpretation vary by manufacturer and testing laboratory. • Results of studies that compare the use of IIF and EIA for ANA testing have been inconsistent, with some showing poor correlation and others demonstrating consistency. Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

9. Background: Rheumatoid Factor Test • Rheumatoid factors (RFs) are specific autoantibodies that react with the Fc fragment of the immunoglobulin (Ig)G molecule. • RFs serve as the basis of sensitive and specific tests for adult rheumatoid arthritis. • 19S IgM-RF is the isotope most frequently used to test for rheumatoid arthritis. • The presence of RF is typically detected by agglutination assays, nephelometry, or enzyme immunoassay. • RFs are not prevalent in pediatric juvenile idiopathic arthritis (<10% of children with juvenile idiopathic arthritis have a positive RF test result). Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

10. Background: Cyclic-Citrullinated Peptide Antibody Test • This test detects the presence of autoantibodies to citrullinated peptides in serum. • Formation of antibodies to cyclic-citrullinated peptide (CCP) seems to be specific for adult patients with rheumatoid arthritis. • In adults, a CCP antibody test is usually ordered along with a rheumatoid factor test when evaluating a patient with inflammatory arthritis. • The prevalence and utility of a positive CCP antibody test in children with juvenile idiopathic arthritis or with associated rheumatic conditions is not clear. Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

11. Agency for Healthcare Research and Quality Comparative Effectiveness Review (CER) Development • Topics are nominated through a public process, which includes submissions from health care professionals, professional organizations, the private sector, policymakers, members of the public, and others. • A systematic review of all relevant clinical studies is conducted by independent researchers, funded by AHRQ, to synthesize the evidence in a report summarizing what is known and not known about the select clinical issue. The research questions and the results of the report are subject to expert input, peer review, and public comment. • The results of these reviews are summarized into Clinician Research Summaries and Consumer Research Summaries for use in decisionmaking and in discussions with patients. The Clinician Research Summary and the full report, with references for included and excluded studies, are available at www.effectivehealthcare.ahrq. gov/anatest.cfm. Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

12. Clinical Questions Addressed by the CER (1 of 3) • Key Question 1: Prevalence and incidence • In children and adolescents aged 18 years or younger, what is the incidence and prevalence of undiagnosed musculoskeletal (MSK) complaints? • In healthy children and adolescents aged 18 years or younger, what is the incidence of positive test results for antinuclear antibody, rheumatoid factor, and cyclic-citrullinated peptide? • Key Question 2: Natural history • What proportion of children and adolescents aged 18 years or younger with undiagnosed MSK pain have pain due to noninflammatory etiologies? • What proportion of children and adolescents aged 18 years or younger with undiagnosed MSK pain have pain due to inflammatory etiologies? • What proportion of children and adolescents aged 18 years or younger experience symptom resolution or recurrence? Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

13. Clinical Questions Addressed by the CER (2 of 3) • Key Question 3: Diagnostic Performance • In children and adolescents aged 18 years or younger with undiagnosed musculoskeletal pain, what is the test performance (sensitivity, specificity, and positive and negative predictive values) of: • ANA for JIA when compared with a clinical diagnosis? • ANA for pSLE when compared with a clinical diagnosis? • RF for pSLE when compared with a clinical diagnosis? • RF for JIA when compared with a clinical diagnosis? • CCP for pSLE when compared with a clinical diagnosis? • CCP for JIA when compared with a clinical diagnosis? Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

14. Clinical Questions Addressed by the CER (3 of 3) • Key Question 4. Accuracy Modifiers • In children and adolescents aged 18 years or younger with undiagnosed MSK pain, do age, sex, race/ethnicity, comorbidities, and recent infections modify the diagnostic performance (sensitivity, specificity, and positive and negative predictive values) of ANA, RF, and CCP for pSLE or JIA when compared with a clinical diagnosis? • Key Question 5. Clinical Impacts of Test Results • In children and adolescents aged 18 years or younger with undiagnosed MSK pain, do ANA, RF, and CCP test results affect referral decisions, additional tests ordered, clinical management, and patient and parent anxiety due to the clinical uncertainty and additional tests? Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

15. Rating the Strength of Evidence From the Comparative Effectiveness Review • The strength of evidence was classified into four broad categories: Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

16. Report Findings: Prevalence of Musculoskeletal Pain Among Healthy Children • Prevalence estimates of musculoskeletal (MSK) pain ranged from 2 to 52 percent, varying with age and sex. • Up to 30 percent of children and adolescents report episodes of pain lasting more than 6 months. • In childhood, the prevalence of JIA was 1 per 1,000, and the prevalence of pSLE was 8.8 per 100,000. • In children with MSK pain, 97 percent of cases result from noninflammatory causes. • Of the 3.3 percent of pediatric cases of MSK pain that result from inflammatory causes: 2.5 percent result from toxic synovitis and 0.8 percent result from inflammatory arthritides. • Recurrence rates of pediatric MSK pain are high and vary by body site. Age, sex, headache, abdominal pain, and combined pain are predictors of recurrence for nontraumatic MSK pain. Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

17. Report Findings: Etiology of Musculoskeletal Pain Among Healthy Children a Prevalence of these etiologies vary with age. Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

18. Report Findings: Prevalence of Positive Serological Test Results Among Healthy Children • The prevalence of positive tests results in healthy children was as follows: • Antinuclear antibody: 0–18 percent (median = 3%) • Rheumatoid factor: approximately 3 percent (median = 0%) • Cyclic-citrullinated peptide antibody: 0–0.6 percent (median <1%) Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

19. Report Findings: Clinical Bottom Line Regarding the Utility of Clinical Testing • The RF test may have a potential application only in confirming a suspected clinical diagnosis of JIA (i.e., a diagnosis based on a comprehensive patient history and physical examination). • One retrospective cohort study examined records of 437 pediatric hospital patients with MSK pain who had an RF test. They found very limited utility of the RF test for diagnosing JIA with a positive predictive value of 45 percent and a negative predictive value of 77 percent (sensitivity = 4.8%; specificity = 98%). • Strength of Evidence: Low • The evidence is insufficient to evaluate the sensitivity and specificity of most test-disease combinations. • Thus, the test performance of the ANA or CCP antibody tests in children with undiagnosed MSK pain is unknown, as is the performance of the RF test for diagnosing pSLE. • Strength of Evidence: Insufficient Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

20. Conclusions (1 of 2) • The prevalence of MSK pain varies with age and sex. • Nearly all MSK pain in children (97%) results from noninflammatory causes. • A review of the patient’s history and performance of an MSK examination remain the most appropriate methods for diagnosing rheumatic etiologies of pediatric MSK pain in a timely fashion. • There is low-strength evidence for the utility of RF in diagnosing JIA in children with undiagnosed MSK pain (sensitivity = 4.8%, specificity = 98%). • The low sensitivity suggests that diagnosis of JIA should not rely on serological tests alone, but may be combined with thorough clinical assessment that suggests the presence of inflammatory arthritis. • The use of laboratory tests as diagnostic measures or for broad screening of pediatric rheumatic conditions remains unsupported. Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

21. Conclusions (2 of 2) • Methodological limitations of existing studies prevent further assessment of the sensitivity and specificity of the ANA, RF, and CCP serological tests. • These serological tests have potential use only as an adjunct to a clinical assessment that suggests the presence of an inflammatory arthritis or connective tissue disease. Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

22. Gaps in Knowledge • No studies examined clinically important outcomes that may affect quality of life and psychosocial well-being. • The impact of the ANA, RF, and CCP test results on referrals, ordering of additional tests, and patient management. • Increase in family anxiety levels due to positive test results, faulty diagnosis of a rheumatic condition, and referral to a pediatric subspecialist. • Studies examined children with known disease status rather than a spectrum of children with undiagnosed MSK symptoms, thus providing evidence regarding test performance that likely overestimates both sensitivity and specificity values. • No studies addressed the patient or clinical characteristics that could modify the accuracy of these serological tests including age, sex, race, history of recent infections, and presence of other characteristics other than MSK pain. Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.

23. What To Discuss With Your Patients • That musculoskeletal pain is common and may recur • That inflammatory causes are found in only 3 percent of children • The important role of a complete patient history and physical examination in diagnosing a rheumatic cause of musculoskeletal pain Wong KO, Bond K, Homik J, et al. Comparative Effectiveness Review No. 50. Available at www.effectivehealthcare.ahrq.gov/anatest.cfm.