title: Association between bone turnover markers, clinical variables, spinal syndesmophytes and bone mineral density in Mexican patients with ankylosing spondylitis.
abstract: OBJECTIVE
  To compare bone turnover marker (BTM) levels and bone mineral density (BMD) between patients with ankylosing spondylitis (AS) and healthy controls (HC) and to evaluate, in AS, the association between BTM levels and clinical variables, spinal syndesmophytes, and BMD using multivariate analysis.
  
  
  METHODS
  Seventy-eight AS patients were compared with 58 HC matched by gender. Spinal syndesmophytes in AS and other characteristics were assessed. C-terminal telopeptide fragments of type I collagen (CTX), bone-specific alkaline phosphatase (BAP), osteocalcin (OC) serum levels, and BMD of the lumbar spine, femoral neck, and forearm were evaluated.
  
  
  RESULTS
  AS males and females had lower BAP levels than their respective HC (p < 0.001 and p = 0.001). AS patients with bridging syndesmophytes had higher OC levels than AS patients either with non-bridging syndesmophytes (p = 0.001) or without spinal syndesmophytes (p < 0.001). OC and CTX levels correlated significantly with the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). In the multivariate linear regression adjusted by age, gender, the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), BMD in the lumbar spine, and C-reactive protein (CRP), we observed an association between BAP levels and anti-tumour necrosis factor (anti-TNF) use (p = 0.05) whereas OC levels were associated with mSASSS (p < 0.001) and anti-TNF use (p = 0.05), and CTX levels were exclusively associated with mSASSS (p = 0.03). In the logistic regression analysis, only OC levels were associated with the presence of syndesmophytes in AS [odds ratio (OR) 2.42, 95% confidence interval (CI) 1.19-5.75].
  
  
  CONCLUSIONS
  We observed an increase in OC levels in AS patients with syndesmophytes. BTM levels were associated with the severity of spinal damage. Future longitudinal studies should evaluate whether these BTMs should be included as tools to determine the prognosis and progression of spinal damage.
authors.affiliation: a Research Unit in Clinical Epidemiology, Specialties Hospital of the National Occidental Medical Centre , Mexican Social Security Institute (IMSS) , Guadalajara , Jalisco , Mexico.
authors.forename: J I
authors.initials: JI
authors.lastname: Gamez-Nava
authors.affiliation: b University Centre of Health Sciences , University of Guadalajara , Guadalajara , Jalisco , Mexico.
authors.forename: L F
authors.initials: LF
authors.lastname: de la Cerda-Trujillo
authors.affiliation: c Department of Epidemiology, Familiar Medicine Unit 4-8, IMSS and University Centre of Health Sciences , University of Guadalajara , Guadalajara , Jalisco , Mexico.
authors.forename: M L
authors.initials: ML
authors.lastname: Vazquez-Villegas
authors.affiliation: d Research Centre of Arthritis and Osteoporosis , Mexicali , Baja California , Mexico.
authors.forename: F
authors.initials: F
authors.lastname: Cons-Molina
authors.affiliation: e Department of Internal Medicine-Rheumatology, Hospital General Regional 45 , IMSS , Guadalajara , Jalisco , Mexico.
authors.forename: M F
authors.initials: MF
authors.lastname: Alcaraz-Lopez
authors.affiliation: f Faculty of Medicine , University of Juárez del Estado de Durango , Gómez Palacio , Durango , Mexico.
authors.forename: S A
authors.initials: SA
authors.lastname: Zavaleta-Muñiz
authors.affiliation: g University Centre of Tonala , University of Guadalajara , Tonala , Jalisco , Mexico.
authors.forename: A D
authors.initials: AD
authors.lastname: Rocha-Muñoz
authors.affiliation: h Research Institute of Rheumatology and Skeletal Muscle System , University Centre of Health Sciences, University of Guadalajara , Guadalajara , Jalisco , Mexico.
authors.forename: E A
authors.initials: EA
authors.lastname: Martinez-Garcia
authors.affiliation: h Research Institute of Rheumatology and Skeletal Muscle System , University Centre of Health Sciences, University of Guadalajara , Guadalajara , Jalisco , Mexico.
authors.forename: E G
authors.initials: EG
authors.lastname: Corona-Sanchez
authors.affiliation: i Division of Health Research, Hospital of the National Occidental Medical Centre , IMSS , Guadalajara , Jalisco , Mexico.
authors.forename: M
authors.initials: M
authors.lastname: Salazar-Paramo
authors.affiliation: j Postdoctoral Fellow Research Program of Postgraduate in Medical Sciences University of Colima, Colima Mexico and LIDF, CUCEL University of Guadalajara , Guadalajara , Mexico.
authors.forename: N S
authors.initials: NS
authors.lastname: Fajardo-Robledo
authors.affiliation: k Department of Anaesthesiology, Specialties Hospital of the Western National Medical Centre , IMSS , Guadalajara , Jalisco , Mexico.
authors.forename: E M
authors.initials: EM
authors.lastname: Olivas-Flores
authors.affiliation: l Department of Physiology, University Centre of Health Sciences , University of Guadalajara , Guadalajara , Jalisco , Mexico.
authors.forename: E G
authors.initials: EG
authors.lastname: Cardona-Muñoz
authors.affiliation: m Department of Internal Medicine-Rheumatology , Hospital General Regional 110, IMSS, Guadalajara, Jalisco, Mexico and CUCS University of Guadalajara , Guadalajara , Jalisco , Mexico.
authors.forename: L
authors.initials: L
authors.lastname: Gonzalez-Lopez
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D015519:Bone Density; D016723:Bone Remodeling; D016022:Case-Control Studies; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D013167:Spondylitis, Ankylosing / Q000097:blood / Q000000981:diagnostic imaging / Q000503:physiopathology*; D055815:Young Adult
chemical_list: D015415:Biomarkers