PMS19 Impact of Disease Severity on the Total, Health-Related, Financial Costs of Treatment of People with Rheumatoid Arthritis in the United Kingdom

Rheumatoid arthritis (RA) causes significant disability and health care expenditures. Whilst RA disability RA is characterized, related cost data are sparse. An RA disability model from a UK biologics register was mapped to the General Practice Research Database (GPRD) (UK) and total health care costs estimated. Step 1: General linear modeling was used to predict HAQ score from RA cases from the biologics register. Step 2: healthcare costs were estimated from RA cases with one year's observation selected from the GPRD. Costs (GBP2011) included prescriptions, consultations and investigations from primary and secondary care. Step 3: the association between healthcare costs and predicted HAQ was explored using Generalized linear modeling (Poisson distribution & log-link) and predicted costs were fitted to predicted disability. Step 1&hibar;Disability was modeled using 6129 cases, (75% female, mean age 57 years (sd 12), mean baseline HAQ 1.81 (0.72)). Six optimal HAQ models included: gender, age, smoking, BMI, prior DMARDs, joint replacements, systemic RA features, current DMARD and steroid treatment, ESR &/or CRP; current non-RA drugs, and co-morbidities. R2 values ranged from 0.277 (no inflammatory marker) to 0.331 (with CRP), while mean HAQ prediction error was 0.13 (0.27). Step 2&hibar;Costs were assessed in 8,423 GPRD cases with similar gender balance (69.8% female) but older mean 64 years). Predicted HAQ (pHAQ) scores ranged from 0.45 to 3.00, with a mean of 1.78 (0.31). Mean annual cost of care in this population was £2792 (£5633), with 46% from hospital admissions, 24% prescriptions, 20% GP consultations, 11% outpatient attendances, and 11% investigations. Step 3&hibar;Total costs (pCOST) were optimally predicted from EXP^(5.613+(Age*0.005)+(pHAQ*1.185)+(Age*pHAQ*-0.001)). pCOST has an exponential correlation to pHAQ (R2=0.986; EXP^(342+(pHAQ*1.188)). Age-adjusted predicted total health care costs for RA patients increased exponentially across the range of estimated disability. Although higher than published estimates, exclusion of support-service costs suggests these values may be conservative.