Estimating indirect costs in primary Sjögren's syndrome

To estimate the indirect costs associated with primary Sjögren's syndrome (pSS) compared with rheumatoid arthritis (RA) and community controls.

Data were obtained from 84 women patients with pSS as part of a study to develop a systemic activity measure, from 87 consecutive women patients with RA attending a hospital clinic, and from 96 women community controls on a general practice list. A modified economic component of the Stanford Health Assessment Questionnaire was used to assess lost productivity.

Using a conservative model, the estimated total annual indirect costs (95% CI) were 7677 pound sterling (5560 pound sterling, 9794 pound sterling) for pSS, 10,444 pound sterling (8206 pound sterling, 12,681 pound sterling) for RA, and 892 pound sterling (307 pound sterling, 1478 pound sterling) for controls. Using a model that maximizes the estimates, the equivalent figures were 13,502 pound sterling (9542 pound sterling, 17,463 pound sterling), 17,070 pound sterling (13,112 pound sterling, 21,028 pound sterling), and 3382 pound sterling (2187 pound sterling, 4578 pound sterling), respectively. These were all significantly greater at p < 0.001 for patient groups than for the control group.

pSS is associated with significantly increased indirect costs equivalent to 69%-83% of that for patients with RA. This needs to be taken into account when evaluating the overall economic consequences of pSS.