Background RA is associated with high societal costs. While disability predicts costs in RA, little is known about the relations between costs and disease activity or health-related quality of life.
Objectives To study the associations between costs, disability, disease activity, and health-related quality of life.
Methods RA patients receiving anti-TNF therapy in southern Sweden (n=2504; median disease duration 11y) were monitored between July 2005 and December 2010. At each visit (n=15732) HAQ, DAS28 and EQ-5D scores were collected, while costs of anti-rheumatic drugs, healthcare use and productivity losses were calculated from 30 days before to 30 days after the visit using nationwide registers. Associations between the clinical measures and healthcare (all patients, applying individual means) and work loss costs (patients <65y; n=1806) were studied by linear regression, adjusting for demographics and disease characteristics, and by Spearman correlation. Confidence intervals were estimated by non-parametric bootstrapping. Due to the inclusion criteria, anti-TNF cost varied little between patients and was excluded from the analyses.
Results Over 60 days, the mean (SD) healthcare cost of patients with ongoing anti-TNF therapy was €3189 (1290), encompassing an anti-TNF cost of €2470 (502; 77%). In patients <65y, the mean work loss cost amounted to €4235 (3450). By linear regression, both healthcare (excl. anti-TNF) and work loss costs were most closely related to HAQ scores, while the association with work loss costs was also higher for EQ-5D than DAS28. Spearman results were similar, but did not detect a closer correlation of healthcare costs with HAQ than DAS28. Healthcare (excl. anti-TNF) costs: B = €440 (95%CI 324-557), 143 (85-201) and -652 (-948 to -355) for each 1.0 difference in HAQ, DAS28 and EQ-5D, respectively (p=0.030 for HAQ vs. DAS28 and p=0.027 for HAQ vs. EQ-5D by comparison of standardised B); rS=0.23, 0.18 and -0.16 for HAQ, DAS28 and EQ-5D, respectively (p=0.085 for HAQ vs. DAS28 and p=0.020 for HAQ vs EQ-5D). Work loss costs: B = €2574 (95%CI 2342-2807), 794 (668-919) and -4817 (-5392 to -4243) (p<0.01 for HAQ vs. DAS28/EQ-5D, p=0.027 for EQ-5D vs. DAS28); rS=0.52, 0.32 and -0.40 (p<0.001 for HAQ vs. DAS28/EQ-5D, p=0.008 for EQ-5D vs. DAS28).
Conclusions In RA, work loss costs are more closely related to disability than to disease activity or health-related quality of life. HAQ disability is also a better marker of healthcare costs than health-related quality of life, while disease activity was not consistently inferior to HAQ in this regard.
Disclosure of Interest None declared