Hypertension, proteinuria, and RAAS inhibition use in children with systemic lupus erythematosus: Data from a multi-institutional pediatric learning health system

ObjectivesTo assess the potential of a multi-institutional pediatric learning health system for comparative effectiveness research in pediatric-onset systemic lupus erythematosus (SLE), we characterized renin angiotensin aldosterone system (RAAS) inhibitor utilization and the feasibility of ascertaining key treatment indications and outcomes, including hypertension and proteinuria.MethodsWe identified children with SLE and lupus nephritis (LN) at 6 PEDSnet institutions using previously developed computable phenotypes. A reference population of controls without SLE was randomly sampled from the same rheumatology/nephrology clinics (<i>N</i> = 200 controls per site). We evaluated data completeness, plausibility, and conformance related to RAAS inhibitor treatment indications and outcomes: (a) percent of encounters with blood pressure (BP) readings, (b) percent of BP readings with paired height, (c) percent of patients with ≥1 urinalysis within 7 days of SLE diagnosis, (d) urinalyses for which proteinuria could be classified as normal or abnormal, and (e) RAAS inhibitor use.ResultsThere were 1303 patients with SLE, including 457 with LN. BP measurements were available at 62% of encounters, of which 96% were paired with a height within 90 days. BP distributions were higher in patients with SLE and LN compared to controls without SLE. One third of SLE patients had a hypertension diagnosis. 60%-83% of patients at each site had a urinalysis protein measurement within 7 days of SLE diagnosis. A normal or abnormal result for proteinuria could be derived for 96% of measurements, and nearly all patients with LN had ≥1 abnormal result (range 94%-100% by site). RAAS inhibitors were prescribed to 31% of SLE and 71% of LN patients (range 60%-84% by site). Hypertension, elevated BP or proteinuria was identified in 90% of SLE cases at the time of RAAS inhibitor initiation.ConclusionWe demonstrated the feasibility of ascertaining health measurement data relevant to pediatric lupus treatment and outcomes in a pediatric learning health system, as well as hospital-level variation in RAAS inhibitor use. This work will facilitate more efficient multi-institutional comparative effectiveness research and also highlights opportunities for increased treatment standardization.