The systemic lupus erythematosus Tri-Nation study: Cumulative indirect costs




We previously reported that patients with systemic lupus erythematosus (SLE) in the US incurred ∼19% and 12% higher direct medical costs than patients in Canada and the UK, respectively, without experiencing superior outcomes expressed as disease damage or quality of life. In the present study, we compared cumulative indirect costs over 4 years in these patients.


A total of 715 patients with SLE (269 US, 231 Canada, 215 UK) were surveyed semiannually for 4 years on employment status and time lost from labor and nonlabor market activities. Cross-country comparisons of indirect costs were performed.


In the US, Canada, and the UK, mean 4-year cumulative indirect costs (95% confidence interval [95% CI]) due to diminished labor market activity were $56,745 ($49,919, $63,571), $38,642 ($32,785, $44,500), and $42,213 ($35,859, $48,567), respectively, and cumulative indirect costs due to diminished nonlabor market activity were $5,249 ($2,766, $7,732), $5,455 ($3,290, $7,620), and $8,572 ($5,626, $11,518), respectively. Regression results showed that cumulative indirect costs (95% CI) due to diminished labor market activity in the US were $6,750 ($580, $12,910) greater than in Canada and $10,430 ($4,050, $16,800) greater than in the UK. Indirect costs due to diminished nonlabor market activity in the US were $280 (−$2,950, $3,520) less than in Canada and $2,010 (−$1,490, $5,510) less than in the UK, both results insignificant due to wide CIs.


Despite American patients incurring greater direct medical costs than Canadian and British patients, they do not experience superior health outcomes in terms of less productivity loss in either labor market or nonlabor market activities.