title: Contribution of vitamin D deficiency to the risk of coronary heart disease in subjects with essential hypertension.
abstract: BACKGROUND
  Vitamin D deficiency is proposed as a risk factor for coronary heart disease (CHD). An inverse relation was observed between serum 25-Hydroxy-Vitamin-D level and incidence of hypertension. This study aimed to evaluate the predictive value of serum 25-Hydroxy-Vitamin-D in improvement of CHD risk-stratification in patients with hypertension.
  
  
  METHODS
  In this cohort, we followed 1586 patients with essential hypertension (1078 diabetic and 508 non-diabetic) for 8.5 years. Physician-adjudicated first hard CHD event was the primary outcome. Cox regression analysis was used to investigate the association between 25-Hydroxy-Vitamin-D quartiles and incident CHD. 25-Hydroxy-Vitamin-D was also added to the Framingham Risk Score (FRS) and Net-Reclassification-Improvement (NRI) and Integrated-Discriminant-Improvement (IDI) were used to examine improved reclassification.
  
  
  RESULTS
  During follow-up, 176 events were recorded. Patients in the lowest quartile of 25-Hydroxy-Vitamin-D experienced the most number of hard CHD events. A significant linear trend was observed in hazard ratios (HR) of incident hard CHD events in 25-Hydroxy-Vitamin-D quartiles which remained significant after multiple adjustments for conventional CHD risk-factors (HRs in full-adjusted model: 2.87 [1.76-4.70] for 1st quartile, 2.31 [1.39-3.83] for 2nd quartile and 1.87 [1.15-3.03] for 3rd quartile, compared with the highest quartile; p-for-trend<0.001). Addition of 25-Hydroxy-Vitamin-D to FRS could improve CHD risk-estimation (relative-IDI = 15%, p-value<0.001). Addition of 25-Hydroxy-Vitamin-D to FRS successfully reclassified 33% [18-49] of patients with hypertension among CHD risk groups (p-value<0.001).
  
  
  CONCLUSIONS
  We observed that serum 25-Hydroxy-Vitamin-D is independently associated with future hard CHD events and improves its prediction in patients with essential hypertension. Addition of serum 25-Hydroxy-Vitamin-D to CHD risk-estimation models may have additive values.
authors.affiliation: Endocrinology and Metabolism Research Center (EMRC), Vali-Asr Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: arash.aan@gmail.com.
authors.forename: Arash Aghajani
authors.initials: AA
authors.lastname: Nargesi
authors.affiliation: Endocrinology and Metabolism Research Center (EMRC), Vali-Asr Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: bh.medstudent@gmail.com.
authors.forename: Behnam
authors.initials: B
authors.lastname: Heidari
authors.affiliation: Endocrinology and Metabolism Research Center (EMRC), Vali-Asr Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: sadaf217@gmail.com.
authors.forename: Sadaf
authors.initials: S
authors.lastname: Esteghamati
authors.affiliation: Endocrinology and Metabolism Research Center (EMRC), Vali-Asr Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: nimahn@gmail.com.
authors.forename: Nima
authors.initials: N
authors.lastname: Hafezi-Nejad
authors.affiliation: Endocrinology and Metabolism Research Center (EMRC), Vali-Asr Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: shb.sara@yahoo.com.
authors.forename: Sara
authors.initials: S
authors.lastname: Sheikhbahaei
authors.affiliation: Endocrinology and Metabolism Research Center (EMRC), Vali-Asr Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: ap.medstudent@gmail.com.
authors.forename: Atieh
authors.initials: A
authors.lastname: Pajouhi
authors.affiliation: Endocrinology and Metabolism Research Center (EMRC), Vali-Asr Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: nakhjavanim@tums.ac.ir.
authors.forename: Manouchehr
authors.initials: M
authors.lastname: Nakhjavani
authors.affiliation: Endocrinology and Metabolism Research Center (EMRC), Vali-Asr Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: esteghamati@tums.ac.ir.
authors.forename: Alireza
authors.initials: A
authors.lastname: Esteghamati
mesh_terms: D003324:Coronary Artery Disease / Q000097:blood / Q000453:epidemiology / Q000209:etiology*; D000075222:Essential Hypertension; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000150:complications*; D015994:Incidence; D007492:Iran / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D018570:Risk Assessment / Q000379:methods*; D013997:Time Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications* / Q000453:epidemiology
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: Coronary heart disease; Hypertension; Risk reclassification; Vitamin D