SLE patients with renal damage incur higher health care costs

Objective. To compare costs and quality of life (QoL) between SLE patients with and without renal damage. Methods. Seven hundred and fifteen patients were surveyed semi-annually over 4 yrs on health care use and productivity loss and annually on QoL. Cumulative direct and indirect costs (2006 Canadian dollars) and QoL (average annual change in SF-36) were compared between patients with and without renal damage [Systemic Lupus International Collaborating Clinics/ACR Damage Index (SLICC/ACR DI)] using simultaneous regressions. Results. At study conclusion, for patients with the renal subscale of the SLICC/ACR DI=0 (n=634), 1 (n=54), 2 (n=15) and 3 (n=12), mean 4-yr cumulative direct costs per patient (95% CI) were $20 337 ($18 815, $21 858), $27 869 ($19 230, $36 509), $51 191 ($23 463, $78 919) and $99 544 ($57 102, $141 987), respectively. In a regression where the renal subscale of the SLICC/ACR DI was a single indicator variable, on average (95% CI), each unit increase in renal damage was associated with a 24% (15%, 33%) increase in direct costs. In a regression where each level in the renal subscale was an indicator variable, patients with end-stage renal disease incurred 103% (65%, 141%) higher direct costs than those without renal damage. Cumulative indirect costs and annual change in the SF-36 summary scores did not differ between patients. Conclusion. SLE patients with renal damage incurred higher direct costs, but did not experience a poorer QoL. QoL may be more influenced by concurrent renal activity than accumulated renal damage, which can occur at any time and patients may gradually habituate to their compromised health state.