Abstract
Background and aims Disease activity increases risk of irreversible organ damage in SLE.
To understand the impact of disease activity (SELENA-SLEDAI) and proportion of time with a certain level of disease activity on risk of developing new organ damage (SLICC/SCR Damage Index (SDI) score).
Methods Cox Proportional hazard models were used to estimate the impact of disease activity as time-dependent variables on the risk of developing any new organ damage over time.
Results Patients (n=2199) were followed for an average of 6.2 years (mean age at cohort entry, 38.0 years; mean disease duration, 5.1 years). The most frequent types of organ damage occurring over time were ocular (cataract) and musculoskeletal (osteoporotic fractures). In Model 1, excluding the variable ”proportion of clinic visits with SLEDAI score >6,” age, and SDI score at cohort entry, SLEDAI score during follow-up and corticosteroid use during follow-up were significant predictors of risk of developing any new organ damage. When including the ”proportion of clinic visits with SLEDAI score >6” (Model 2), SLEDAI score during follow-up was no longer significant. in Model 3, excluding the time-dependent variable ”SLEDAI score during follow-up” from the model, the effect of “proportion of clinic visits with SLEDAI score >5 was slightly reduced but remained significant.
Conclusions Higher organ damage risk was observed in patients with high levels of disease activity for a greater time compared to those with high levels of disease activity for a lesser time. These findings call for active measures to control disease activity over time in SLE.
Time-dependent cox proportional hazard models: effect of disease activity on the risk of new organ damage.
