Background/Purpose:

We have shown that cognitive function followed particular trajectories over time in SLE, with some patients having persistently low scores and others normal scores. This study aims to: 1) describe the association between cognitive function trajectories and depressive symptoms trajectories and 2) identify baseline factors associated with trajectory membership.

Methods:   Data were from the University of California San Francisco Lupus Outcomes Study, in which participants are followed longitudinally via annual telephone surveys. The Hopkins Verbal Learning Test-Revised (HVLT-R; measures verbal memory) was administered in years 2-7, providing up to 6 of observation. Age- and education-stratified z-scores were derived for HVLT delayed recall. The Center of Epidemiologic Studies Depression Scale (CES-D: score range 0–60; score ≥ 24 represents depression) was administered yearly.

Combined trajectory modelling for HVLT-R and CES-D was performed. Models with up to 6 classes were assessed. The best model was determined by a combination of clinical plausibility and statistical criteria. Univariate/multivariable logistic regression analyses examined baseline (year 2) factors associated with class memberships, including sex, ethnicity, disease duration, treatments, fatigue, and self-reported disease activity.  

Results:   755 patients (mean age 35 ± 13 years at SLE diagnosis) were studied. 4 latent classes were identified: 1-low CES-D scores and low cognitive scores (no depression + cognitive impairment; 20%), 2-lowest CES-D scores and highest normal cognitive scores (no depression + normal cognition; 48%), 3-highest CES-D scores and lowest cognitive scores (depression + cognitive impairment) (9%), and 4-high CES-D scores and normal cognitive score (depression + normal cognition; 23%) (Figure 1).

Table 1 shows the association between baseline variables and membership in classes 2 and 3. Caucasian ethnicity and education were associated with normal cognitive function. SLE disease activity and duration, fatigue, and methotrexate use (reflecting disease activity) were associated with cognitive impairment.

Conclusion:  4 distinct classes of combined cognitive function and the depressive symptoms were identified. Cognitive function was associated with depression status in 32% of patients (class 2 and 3). The results also confirmed that other factors predicted the latent class membership; such as ethnicity, education, disease activity and fatigue. These results highlight different aspects relevant for assessing and managing cognitive function over time in SLE.