Objective: To investigate the occurrence of ischemic heart disease (IHD) in a cohort of 104 Danish patients with biopsy-proven lupus nephritis (LN).
Methods: Information on all hospitalizations in Denmark for IHD between 1977 and 2006 was obtained from the Danish National Hospital Register. Occurrence of IHD after date of first renal biopsy in the LN cohort was compared to the occurrence of IHD in the general population by calculation of standardized ratios of observed to expected events (O:E ratios) for different manifestations of IHD registered during inpatient and outpatient hospital visits.
Results: The median duration of followup was 14.7 (range 0.1-30.0) years. Thirty-one first-time hospitalizations for IHD occurred in the cohort, yielding an overall O:E ratio for IHD of 6.8 (95% CI 4.6-9.7). Increased risks were found for angina pectoris (O:E ratio 6.0, 95% CI 3.0-11), myocardial infarction (O:E ratio 7.9, 95% CI 3.8-15), and other IHD-related diagnoses combined (O:E ratio 6.9, 95% CI 3.3-13). A high IHD risk was observed for patients aged < 31 years at time of first renal biopsy (O:E ratio 17.1, 95% CI 9.1-29) and for patients aged 30-39 years during followup (O:E ratio 42.3, 95% CI 21-76). Patients undergoing chronic renal replacement therapy also had a pronounced risk of IHD (O:E ratio 19.4, 95% CI 7.8-40).
Conclusion: LN is associated with markedly increased morbidity from IHD. Our findings indicate that patients with early-onset LN have a disturbingly high risk of IHD compared to the general population.