Disease activity, function and costs in early rheumatoid arthritis

Abstract: Rheumatoid arthritis (RA) is a major cause of progressive joint damage and disability, and is associated with decline in quality of life, reduced ability to work and increased health care utilisation. The economic consequences of the disease are substantial for the individuals and their families and for the society as a whole. This thesis describes a 5-year follow up of 320 patients with early RA, enrolled between January 1996 and April 1998 in the Swedish multi-centre inception cohort TIRA (early interventions in rheumatoid arthritis). Health status, function and costs were investigated. Predictors of high costs were calculated, and an algorithm was constructed to predict future need for TNFinhibitor treatment in patients not responding to traditional disease-modifying antirheumatic drugs (DMARDs). Clinical and laboratory data, measures of functional capacity and self-reported assessments were collected regularly. In addition, patients completed biannual/annual questionnaires concerning all health care utilisation and days lost from work due to the disease. Within 3 months, improvements were seen regarding all variables assessing disease activity and functional ability, but 15% of the patients had sustained high or moderate disease activity throughout the study period. The scores of ‘health assessment questionnaire’ (HAQ) were similar for men and women at baseline, but had a less favourable course in women, who also had DMARDs more frequently prescribed.Ambulatory care accounted for 76% of the direct costs during the first year. Women had more ambulatory care visits and higher usage of complementary medicine compared to men. Men ?65 years had low costs compared to younger men and compared to women of all ages. In multiple logistic regression tests, HAQ, high levels of IgM-class rheumatoid factor (RF), and poor hand function increased the odds of incurring high direct costs. Poor hand function and pain increased the odds of incurring high indirect costs.Indirect costs exceeded direct costs all three years. The average direct costs were €3,704 (US$ 3,297) year 1 and €2,652 (US$ 2,360) year 3. All costs decreased over the years, except those for medication and surgery. The indirect costs were €8,871 (US$ 7,895) year 1 and remained essentially unchanged, similarly for both sexes. More than 50% were on sick leave or early retirement at inclusion. Sick leave decreased but was offset by increase in early retirement. 14 patients (5%) were prescribed TNF-inhibitors at the 3- year follow up, thus increasing drug costs substantially. However, they incurred higher costs even before prescription of anti-TNF therapy.At the 5-year follow-up (2001-2003), 31 patients (12%) were prescribed TNFinhibitors. Baseline values of erythrocyte sedimentation rate, C-reactive protein, anti-CCP antibodies and morning stiffness were significantly higher in this group. These patients were also to a larger extent RF-positive and carriers of the ‘shared epitope’ (SE). Anti-TNF treated patients were significantly younger and more often women. For men, a predictive model was constructed using baseline data including SE+ and IgA-RF >100 U/L and anti-CCP >240 U/L yielding a specificity of 98% and a sensitivity of 71%. For women, disease activity score (DAS28) at the 3-month follow-up proved to be a better predictor, and the final model comprised SE+ and 3-month DAS28>5.2, giving a specificity of 95% and a sensitivity of 59%.