PURPOSE: The treatment of systemic lupus erythematosus (SLE) is complex, with a wide range of drugs commonly prescribed. The aims of this study were to identify longitudinal treatment patterns in patients with incident SLE and to estimate the associations of treatment patterns with clinical and economic outcomes.
METHODS: This retrospective, observational cohort study used a US managed care claims database to identify patients with newly diagnosed SLE and 4-year treatment follow-up. Patients were aged greater than or equal to 18 years, with continuous medical and pharmacy benefits for 12 months before and 48 months after the index date (first medical claim with a diagnosis of SLE). Longitudinal treatment patterns were grouped using a k-means cluster analysis. Therapies were included in the cluster analysis if the mean number of prescriptions in each year was greater than or equal to 0.05. Clinical and economic outcomes were compared across clusters using multivariate regression analyses.
FINDINGS: Data from 1611 patients with incident SLE were analyzed (91.4% women; mean [SD] age, 44.5 [9.5] years; 56.2% managed primarily by a specialist). Hydroxychloroquine and corticosteroids were the most commonly prescribed therapies; methotrexate, azathioprine, and mycophenolate mofetil also met the criteria for inclusion in the cluster analysis. Ten treatment clusters were identified; the most common was minimally treated patients (42.8%). Hydroxychloroquine monotherapy, corticosteroid monotherapy, and corticosteroid/hydroxychloroquine combination therapy were received by 34.0%, 11.2%, and 7.8% of patients, respectively. Methotrexate or azathioprine with a corticosteroid/hydroxychloroquine were received by 4.2% of patients. Changes in therapy, except discontinuations, were rare. Compared with the minimally treated cluster, those that received corticosteroid monotherapy (mean dose, greater than 12.0 mg/d) had poorer clinical and economic outcomes; the hydroxychloroquine-monotherapy cluster had similar or better outcomes; and patients who received a corticosteroid/hydroxychloroquine with or without methotrexate or azathioprine demonstrated outcomes that were poorer but that appeared better than those with corticosteroid monotherapy. SLE-related visits with a nonspecialist were common (~45%) and remained unchanged over time despite better clinical and economic outcomes associated with specialist visits.
IMPLICATIONS: This study utilized cluster analysis, an unsupervised machine-learning method, to systematically discern treatment patterns over 4 years and to estimate outcomes associated with the identified treatment patterns. The results suggest that minimal treatment is the most common approach in patients with newly diagnosed SLE. Clinical and economic outcomes are poorest with corticosteroid monotherapy but may improve with the addition of hydroxychloroquine and/or an immunosuppressive agent. A large proportion of SLE care is provided by nonspecialists despite the potential benefits of involving a specialist.
