The Medical Outcomes Study Short Form 36 (SF-36) and Lupus Quality of Life (LupusQoL) are health-related quality of life questionnaires used in systemic lupus erythematosus (SLE). We first determined the hypothesis-testing construct validity of the SF-36 and LupusQoL against disease activity in patients with active SLE and then compared the sensitivity to change of SF-36 and LupusQoL domains according to different definitions of minimum clinically important differences (MCIDs) for improvement and worsening in the current cohort.
Seventy-eight clinically active SLE patients concurrently completed both questionnaires at their baseline and followup visits. Questionnaire domain scores were correlated with the SLE Disease Activity Index 2000 (SLEDAI-2K) and evaluated for floor/ceiling effects. The sensitivity to change of domains in each questionnaire was analyzed first, according to the various MCID definitions and, second, by clinically meaningful changes in disease activity. The magnitudes of change in each domain score between the baseline and followup visit were evaluated using standardized response means.
In the 78 patients, the mean ± SD SLEDAI-2K scores were 9.7 ± 4.8 at baseline and 8.8 ± 5.1 at followup. SF-36/LupusQoL domain scores did not correlate with disease activity. The SF-36 showed floor effects, and ceiling effects were evident in both questionnaires. All domains of both questionnaires showed sensitivity to change over time. Specific domains that reflected worsening or improvement differed according to differing MCID definitions.
In SLE patients with active disease, both the SF-36 and LupusQoL are sensitive to change, reflecting both improvement and worsening. More importantly, the LupusQoL SLE-specific domains (planning, burden to others, body image, and intimate relationships) were largely responsive to change.