title: Bone mineral density and carotid atherosclerosis in systemic lupus erythematosus: a controlled cross-sectional study.
abstract: BACKGROUND
  As osteoporosis is reported to be associated with atherosclerosis in the general population we examined the relationship between bone mass and carotid measurements in patients with systemic lupus erythematosus (SLE) and controls, and possible links between them in SLE.
  
  
  METHODS
  In a cross-sectional study, 111 SLE-patient were compared with 111 age- and sex-matched controls, mean age 48.7(12.9) years, 89% were women, of which 51% postmenopausal. Carotid intima media thickness (cIMT), carotid plaque occurrence and echogenicity were determined by B-mode ultrasound and bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA).
  
  
  RESULTS
  BMD and cIMT were inversely associated both in patients and controls. Patients, but not controls, with carotid plaque had higher cIMT at low BMD than at normal BMD, p = 0.010. Logistic regression indicated more than doubled odds ratio (OR) of carotid plaque in patients, particularly in post-menopausal women, than in controls in relation to all BMD measurements. For low BMD at hip, significant increased OR for echolucent plaque was shown for patients compared with controls. In patients, significant impact of age, body mass index, smoking, systolic blood pressure, blood lipids, diabetes mellitus, impaired renal function, low levels of complement C3 and C4, history of nephritis, SLE-damage index and ever use of antimalarial was found for association between BMD and higher cIMT and carotid plaque. In multivariate regression, low C4 was independent contributor to association between total BMD and upper cIMT tertile, accounted for OR (95% confidence interval) of 3.2 (1.03-10.01), and also for association with bilateral carotid plaque, OR of 4.8 (1.03-22.66). The contribution of low C4 for the association between BMD and carotid atherosclerosis was enhanced within the second and third tertiles of total BMD.
  
  
  CONCLUSIONS
  This study is the first to demonstrate inverse association between BMD and carotid measurements in both SLE-patients and controls. Our results suggest that SLE-patients may suffer higher burden of (sub)clinical atherosclerotic disease, especially presence of both echolucent and echogenic plaque, than controls with the same bone mineral status. Low complement C4 seems to play an important role in earlier development of carotid atherosclerosis already within (sub)normal ranges of total BMD in patients.
authors.affiliation: Department of Medicine, Unit of Rheumatology, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, 141 86, Sweden. sofia.ajeganova@ki.se.
authors.forename: Sofia
authors.initials: S
authors.lastname: Ajeganova
authors.affiliation: Department of Clinical Physiology, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, 141 86, Sweden. thomas.gustafsson@ki.se.
authors.forename: Thomas
authors.initials: T
authors.lastname: Gustafsson
authors.affiliation: Department of Clinical Physiology, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, 141 86, Sweden. tomas.jogestrand@ki.se.
authors.forename: Tomas
authors.initials: T
authors.lastname: Jogestrand
authors.affiliation: Section of Immunology and Chronic disease, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, 171 77, Sweden. johan.frostegard@ki.se.
authors.forename: Johan
authors.initials: J
authors.lastname: Frostegård
authors.affiliation: Department of Medicine, Unit of Rheumatology, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, 141 86, Sweden. ingiald.hafstrom@karolinska.se.
authors.forename: Ingiäld
authors.initials: I
authors.lastname: Hafström
mesh_terms: D000328:Adult; D015519:Bone Density; D002340:Carotid Artery Diseases / Q000175:diagnosis* / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged