Development and validation of a disease‐specific health‐related quality of life measure, the LupusQol, for adults with systemic lupus erythematosus

Abstract

Objective. To develop and validate a disease-specific health-related quality of life (HRQOL) instrument for adults with systemic lupus erythematosus (SLE).Methods. The work consisted of 6 stages. Stage 1 included item generation for questionnaire content from semistructured interviews with SLE patients. In stage 2 item selection for the draft questionnaire was performed by thematic analysis of the patient interview transcripts and expert panel agreement. In stage 3 the content validity of the draft questionnaire was assessed by patients completing the questionnaire and providing critical feedback. In stages 4 and 5 construct validity and internal reliability of the 3 versions of the LupusQoL were evaluated using principal component analysis with varimax rotation and Cronbach's alpha coefficients, respectively. In stage 6 discriminatory validity, concurrent validity, and test-retest reliability were evaluated.

Sensitivity to Change and Minimal Important Differences of the LupusQoL in Patients With Systemic Lupus Erythematosus

“…Notably, the original LupusQoL mean scores derived from consecutive outpatients at UK centers were strikingly higher (by approximately 20–25 points) across all domains 8 than the baseline values for these patients with moderate or severe flares. Such large differences suggest that a flare of SLE has a very significant impact on all aspects of HRQOL and may also explain why the LupusQoL is less responsive to deterioration of disease activity, as patients already have poor health.…”

“…The original English version of the LupusQoL (4‐week recall period) 8 was completed by the participant at each time point. It has 8 domains: physical health, pain, planning, body image, burden to others, intimate relationships, emotional health, and fatigue.…”

“…It has acceptable ceiling effects and minimal floor effects. Scoring of each domain of the LupusQoL is such that 0 = worst health and 100 = best health 8.…”

“…An anchor‐based method was used as the primary approach (as preferred by the FDA) 2, based on the average change in LupusQoL or SF‐36 scores for the subset of patients who were considered to have a small but discernible change in that particular HRQOL domain. These analyses were complemented by distribution‐based approaches based around the common standards of 1 SEM, using data from McElhone et al 8 and 0.5 SD, which corresponds to a medium effect 28, 29.…”

“…The LupusQoL is a valid, reliable, patient‐derived, disease‐specific HRQOL measure for adults with SLE 8 that contains items/domains more relevant to patients with SLE than generic measures 9. As with many HRQOL measures, the interpretation of the data may be problematic and should not be based solely on P values, especially if HRQOL is a secondary outcome when a trial tends not to be powered for HRQOL.…”