title: Predicting the 10-year risk of hip and major osteoporotic fracture in rheumatoid arthritis and in the general population: an independent validation and update of UK FRAX without bone mineral density.
abstract: OBJECTIVE
  FRAX incorporates rheumatoid arthritis (RA) as a dichotomous predictor for predicting the 10-year risk of hip and major osteoporotic fracture (MOF). However, fracture risk may deviate with disease severity, duration or treatment. Aims were to validate, and if needed to update, UK FRAX for patients with RA and to compare predictive performance with the general population (GP).
  
  
  METHODS
  Cohort study within UK Clinical Practice Research Datalink (CPRD) (RA: n=11 582, GP: n=38 755), also linked to hospital admissions for hip fracture (CPRD-Hospital Episode Statistics, HES) (RA: n=7221, GP: n=24 227). Predictive performance of UK FRAX without bone mineral density was assessed by discrimination and calibration. Updating methods included recalibration and extension. Differences in predictive performance were assessed by the C-statistic and Net Reclassification Improvement (NRI) using the UK National Osteoporosis Guideline Group intervention thresholds.
  
  
  RESULTS
  UK FRAX significantly overestimated fracture risk in patients with RA, both for MOF (mean predicted vs observed 10-year risk: 13.3% vs 8.4%) and hip fracture (CPRD: 5.5% vs 3.1%, CPRD-HES: 5.5% vs 4.1%). Calibration was good for hip fracture in the GP (CPRD-HES: 2.7% vs 2.4%). Discrimination was good for hip fracture (RA: 0.78, GP: 0.83) and moderate for MOF (RA: 0.69, GP: 0.71). Extension of the recalibrated UK FRAX using CPRD-HES with duration of RA disease, glucocorticoids (>7.5 mg/day) and secondary osteoporosis did not improve the NRI (0.01, 95% CI -0.04 to 0.05) or C-statistic (0.78).
  
  
  CONCLUSIONS
  UK FRAX overestimated fracture risk in RA, but performed well for hip fracture in the GP after linkage to hospitalisations. Extension of the recalibrated UK FRAX did not improve predictive performance.
authors.affiliation: Division of Pharmacoepidemiology & Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.
authors.forename: Corinne
authors.initials: C
authors.lastname: Klop
authors.affiliation: Division of Pharmacoepidemiology & Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.|MRC Lifecourse Epidemiology Unit, Southampton General Hospital, Southampton, UK.|Department of Clinical Pharmacy & Toxicology, Maastricht University Medical Centre, Maastricht, The Netherlands.|Department of Epidemiology, Maastricht University/CAPHRI, Maastricht, The Netherlands.
authors.forename: Frank
authors.initials: F
authors.lastname: de Vries
authors.affiliation: Department of Rheumatology & Clinical Immunology, University Medical Center, Utrecht, The Netherlands.
authors.forename: Johannes W J
authors.initials: JW
authors.lastname: Bijlsma
authors.affiliation: Division of Pharmacoepidemiology & Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.
authors.forename: Hubert G M
authors.initials: HG
authors.lastname: Leufkens
authors.affiliation: Department of Rheumatology & Clinical Immunology, University Medical Center, Utrecht, The Netherlands.|Department of Epidemiology, Julius Center for Health Sciences and Primary Care, University Medical Center, Utrecht, The Netherlands.
authors.forename: Paco M J
authors.initials: PM
authors.lastname: Welsing
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000150:complications*; D002138:Calibration; D016022:Case-Control Studies; D015331:Cohort Studies; D016208:Databases, Factual; D005260:Female; D006620:Hip Fractures / Q000453:epidemiology / Q000209:etiology*; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D058866:Osteoporotic Fractures / Q000453:epidemiology / Q000209:etiology*; D011237:Predictive Value of Tests; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D006113:United Kingdom / Q000453:epidemiology
keywords: Epidemiology; Osteoporosis; Rheumatoid Arthritis