ObjectiveTo demonstrate the value of diagnosing axSpA, by comparing health and costs associated with available diagnostic algorithms and perfect diagnosis.MethodsUsing data from SPACE and other... Show moreObjectiveTo demonstrate the value of diagnosing axSpA, by comparing health and costs associated with available diagnostic algorithms and perfect diagnosis.MethodsUsing data from SPACE and other cohorts, a model was developed to estimate health (quality-adjusted life-years, QALYs) and costs (healthcare consumption and work productivity losses) of different diagnostic algorithms for axSpA amongst patients with low back pain referred to a rheumatologist, over a 60-year horizon. The model combined a decision-tree (diagnosis) with a state-transition model (treatment). The three algorithms (Berlin [BER, highest specificity], Modification 1 [M1; less strict inflammatory back pain (IBP) criterion] and Modification 2 [M2; IBP not mandatory as entry criterion, highest sensitivity]) were compared. Changes in sensitivity/specificity were explored and the value of perfect diagnosis was investigated.ResultsFor each correctly diagnosed axSpA patient, up to 4.7 QALYs and €60,000 could be gained/saved, considering a societal perspective. Algorithm M2 resulted in more health and lower costs per patient (24.23 QALYs; €157,469), compared to BER (23.96 QALYs; €159,423) and M1 (24.15 QALYs; €158,417). Hypothetical improvements in M2 sensitivity resulted in slightly more value compared to improvements in specificity. Perfect diagnosis can cost €7,500 per patient and still provide enough value.ConclusionCorrect diagnosis of axSpA results in substantial health and cost benefits for patients and society. Not requiring IBP as mandatory for diagnosis of axSpA (algorithm M2) provides more value and would be preferable. A considerably more expensive diagnostic algorithm with better accuracy than M2 would still be considered good value for money. Show less
In this thesis we aimed to investigate the burden of axial spondyloarthritis (axSpA) in an early phase. We have emphasized three main themes: (1) the value of a positive family history of SpA; (2)... Show moreIn this thesis we aimed to investigate the burden of axial spondyloarthritis (axSpA) in an early phase. We have emphasized three main themes: (1) the value of a positive family history of SpA; (2) the impact of axSpA on health outcomes in an early phase of axSpA; and (3) illness perceptions and coping strategies of patients with axSpA.We have shown that when broad HLA-B27 testing is not useful, the presence of a positive family history of axSpA or uveitis could be used to predict HLA-B27 positivity in patients suspected of axSpA. We have demonstrated that health-related quality of life work productivity, and daily activities are seriously impacted even in the earliest phase of the axSpA and remain substantial over time. We have further shown that illness perceptions are important in the relationship between back pain and health outcomes in patients with axSpA. Our results suggest that illness perceptions and coping strategies do not change spontaneously and are rather independent of a decrease in disease status in patients with early axSpA.The knowledge and insights of this thesis could help us in making a timely diagnosis, providing treatment sooner, and exploring additional treatment options, which in turn could hopefully reduce the burden of axSpA. Show less
