Background/Purpose: We have observed a decline in rates of cardiovascular events in systemic lupus erythamatosus (SLE) pateints in our clinic. In this work presented below, we have quantified the decline in rates and assessed the degree to which the decline could be explained by changes in medication use (greater use of hydroxychoroquine, reduced use of corticosteroids), tighter control of cardiovascular risk factors, or demographic changes in our clinic.

Methods: This analysis is based on retrospective data from the Hopkins Lupus Cohort experience since 1993.  A cardiovascular event (CVE) was defined as the occurrence of a stroke, myocardial infarction (MI),  coronary procedure, incident angina, or claudication.  The analysis was performed based on a data set with one record per patient-month of participation in the Hopkins Lupus Cohort.  Each record contained data regarding the patient’s clinical history up until that time, the most recently measured levels of disease activity, medications taken at that time, and whether a CVE occurred during that month.  Using this file, rates of CVE per person-year of follow-up were calculated for subgroups of follow-up defined by date, medication, disease activity, and demographics.  Multivariable models were fit using pooled logistic regression.

Results:  Table 1 shows the rates of CVE at different periods of time.  The rate of events dropped by approximately 50% after 2010.   Table 2 shows the rates of events by calendar time in strata defined by potentially explanatory variables.  The reduction in CVE rates after 2010 was observed in all strata defined by corticosteroid or hydroxychloroquine use, systolic blood pressure, and lupus disease activity.  Based on a multivariable model, the reduced rates of CVE after 2010 persisted after adjusting simultaneously for age, race, sex, recent systolic blood pressure and serum cholesterol, history of diabetes, smoking, recent SLE disease activity, corticosteroid dose and hydroxychloroquine use (Odds ratio comparing 2010-2014 to previous years: 0.53, 95% confidence interval 0.32, 0.88, p-value=0.015)

Table 1:  Rate of cardiovascular events during cohort participation by year

Table 2.  Rates of cardiovascular events by period in strata defined by potentially confounding or explanatory variables.

Conclusion: The reduced rate of cardiovascular events could not be explained by demographics, medications, cardiovascular risk factors, or lupus-specific variables.  Further work is needed to explain the drop in rates.  Identifying the reason for the drop in rates could have important implications for CVE prevention among SLE patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/unexplained-decline-in-rates-of-cardiovascular-events-in-a-large-cohort-of-sle-patients/