Background Remission and Low Disease activity state (LDAS) are the treat to target (T2T) outcomes used Systemic Lupus Erythematosus (SLE). Lupus Impact Tracker (LIT), a ten item unidimensional patient reported (PRO) tool with good psychometric properties and responsiveness including to composite response Index (SRI) and T2T outcomes. SLE patients often fibromyalgia (FM). We report discriminant validity of LIT to T2T outcomes in SLE patients stratified by FM from the largest European SLE registry- cohort.
Methods Observational, multi-center data from 1364 adult patients with SLE meeting 1997 ACR criteria were obtained. This included demographics, LIT, disease activity-DA (SLEDAI) and medications. Remission off therapy (ROFT) was defined as SLEDAI=0 without prednisone or Immunosuppressive/s. Remission on-therapy (RONT) was SLEDAI=0 and a prednisone dose 5 mg/day and/or Immunosuppressive/s. LDAS (modified) was SLEDAI 4, prednisone dose 9 mg/day and/or maintenance immunosuppressive/s. Non-optimal (NO) disease status was SLEDAI >4 and/or prednisone dose >9 mg/day and/or immunosuppressive/s in induction dose. LIT values were compared between T2T groups using mixed models among (a) all patients, (b) with and (c) without FM. For Model 1 : RONT and LDAS were combined (given relatively very low DA and lower prevalence of steroid use in LDAS) and compared with NO and ROFT. For model 2, all 4 T2T categories were used.
Results 1232/1364 (90%) were women, and 95% were Caucasian,76/1364 had FM. Median LIT (Q1, Q3) was 25 (10,46.3). LIT scores were significantly different among T2T categories (table 1). Significant relevant differences were not evident between RONT and LDAS groups: 1) RONT had greater medication use than LDAS (prednisone 5–10 mg/day use of 17.2% vs 8.3%)). 2) In LDAS, mean SLEDAI was 2, which can occur without clinical DA. RONT thus fared slightly worse than LDAS in patients evaluation of SLE impact.
LIT was able to differentiate between T2T outcomes, and the scores moved in the anticipated direction. Though LIT scores for RONT were lower than NO in those with FM, they did not reach significance. This could potentially be secondary to small number of FM patients and use of 4 comparator categories.
Conclusions LIT can differentiate between T2T outcomes in SLE patients with and without FM. Given its extensive validation in various languages, regions, measurement equivalence, ease of use, acceptability by patients and physicians, and responsiveness to changes in assessments by physician (SLEDAI, PGA, SRI, T2T) and patient (HRQOL, SLAQ), the tool is indicated for routine patient care, research and clinical trials.
Funding Source(s): None
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