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BackgroundHypertension is prevalent and contributes significantly to cardiovascular risk in patients with systemic lupus erythematosus (SLE). Primary aldosteronism (PA), the most common endocrine cause of hypertension, confers higher cardiovascular risk than essential hypertension and has been linked to autoimmune diseases including SLE. While the prevalence of PA in SLE is unknown, a third of patients in a tertiary lupus clinic have been demonstrated to have clinical indications for PA testing.ObjectivesTo compare SLE phenotypes and outcomes in patients attending the clinic with and without indications for PA testing.MethodsIn this retrospective study, hypertension was defined as blood pressure ≥140/90 on two clinic visits, or a documented diagnosis of hypertension. Baseline demographic and SLE disease characteristics were compared between patients with and without an indication for PA testing as determined according to the 2016 Endocrine Society guidelines, before multivariable regression analyses assessed for associations between having an indication for PA testing with disease phenotypes and outcomes specifically within the subset of patients with hypertension.ResultsOf 322 patients with SLE, 95 patients (30%) had at least one indication for PA testing. These patients were older, had longer SLE disease duration, higher body mass index, higher blood pressure, and more baseline organ damage compared to those without an indication for PA testing. Over the period of clinic attendance (median 6.8 years), these patients had greater accrual of organ damage, higher flare rates, and more frequent proteinuria. Within the subset of hypertensive patients, indications for PA testing were independently associated with reduced baseline renal function (adjusted OR 3.29, 95% CI 1.30-9.47; p = 0.017), higher baseline organ damage (adjusted OR 1.94, 95% CI 1.03-3.73; p = 0.043), and higher prevalence of flare throughout the study period (adjusted OR 2.86, 95% CI 1.04-8.60; p = 0.049) in multivariable modelling.ConclusionSLE patients with an indication for PA testing exhibit a phenotype characterised by impaired renal function, increased organ damage and higher prevalence of flare. Further research is needed to prospectively assess whether the increased burden is attributable to PA, other causes of hypertension, or the severe hypertension.