title: A predictive model of vitamin D insufficiency in older community people: from the São Paulo Aging & Health Study (SPAH).
abstract: OBJECTIVE
  To evaluate the prevalence of 25-hydroxyvitamin D insufficiency (25OHD<20 ng/mL) and to develop a predictive model for this status.
  
  
  METHODS
  This is a cross-sectional study including 908 community-dwelling older subjects, 18% (158) of which were randomly selected to be a "test" sample, with the remaining (750) composing a "development" sample. A radioimmunoassay technique was used to measure 25OHD levels. Anthropometrical data, information about lifestyle habits and co-morbidities were obtained. Multiple logistic regression models were created. An Index Risk of Vitamin D Insufficiency (IRVDI) was designed and subsequently validated. The performance of this tool was assessed through ROC analysis.
  
  
  RESULTS
  The prevalence of 25OHD<20 ng/mL was of 58.0% (CI 95% 51.6-64.6). The clinical independent factors for 25OHD<20 ng/mL were female gender (OR=2.16; 95%CI 1.13-4.13; p=0.020), diabetes (OR=1.84; 95%CI 1.23-2.74; p=0.003) and season (winter/spring) (OR=3.63, 95%CI 2.62-4.88; p<0.001). After statistical adjustments, the IRVDI was able to identify older people at risk for vitamin D insufficiency with a sensitivity of 55.9%, specificity 72.3% and ROC area of 0.685 (p<0.001).
  
  
  CONCLUSIONS
  Our results suggest that vitamin D insufficiency is common among Brazilian community-dwelling elderly. Female gender, diabetes and the season (winter/spring) were the important parameters that predicted this status. The clinical use of these parameters can be help to design and target appropriate public health interventions. The IRVDI is a convenient tool for the selection of older people at risk for vitamin D insufficiency.
authors.affiliation: Bone Metabolism Laboratory, Rheumatology Division, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Jaqueline B
authors.initials: JB
authors.lastname: Lopes
authors.affiliation: Bone Metabolism Laboratory, Rheumatology Division, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Georgea H
authors.initials: GH
authors.lastname: Fernandes
authors.affiliation: Bone Metabolism Laboratory, Rheumatology Division, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Liliam
authors.initials: L
authors.lastname: Takayama
authors.affiliation: Bone Metabolism Laboratory, Rheumatology Division, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Camille P
authors.initials: CP
authors.lastname: Figueiredo
authors.affiliation: Bone Metabolism Laboratory, Rheumatology Division, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil. Electronic address: rosamariarp@yahoo.com.
authors.forename: Rosa M R
authors.initials: RM
authors.lastname: Pereira
mesh_terms: D000368:Aged; D001938:Brazil / Q000453:epidemiology; D003430:Cross-Sectional Studies; D003920:Diabetes Mellitus / Q000097:blood; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D008019:Life Style; D016015:Logistic Models; D008297:Male; D008954:Models, Biological; D016017:Odds Ratio; D015995:Prevalence; D012372:ROC Curve; D012111:Residence Characteristics; D018570:Risk Assessment; D012621:Seasons; D012737:Sex Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology* / Q000209:etiology; D014815:Vitamins / Q000097:blood*
chemical_list: D014815:Vitamins; D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: 25-Hydroxyvitamin D; Diabetes; Older; Predictive risk factors; Prevalence; Season