To enable confounder adjustment for categorical variables, index cases, relatives and spouses were re-categorised as cases or controls, to permit analysis by logistic regression, using two different strategies: (a) Relatives were divided into cases and controls based VX-689 cost upon an arbitrary threshold

Selleck C59 wnt identified after inspection of BMD distributions (the HBM definition for spouses was as for index cases) and (b) all relatives were combined with unaffected spouses to act as controls. Random-effects models were used to allow for the lack of statistical independence due to within-family clustering of environmental factors and shared genotypes. Crude and adjusted mean differences and cluster-specific odds ratios (OR), with 95% CIs, are presented. No family had >10 members. When rho, the measure of within-family correlation, Selleck BIBF-1120 was large (>0.25), OR reliability was checked by refitting the model at different quadrature points and ensuring the coefficient relative differences were <0.01. Data were managed using Microsoft Access (data entry checks; error rate <0.12%) and analysed using Stata release 11 statistical software (StataCorp, College Station, TX, USA). Results HBM prevalence on DXA databases In total, 335,115 historical DXA scans were screened across 13 databases, collected over a combined total of 110.2 years, the earliest from 1992. DXA scans of all those with T- or Z-scores ≥ +4 from ten centres were inspected

by both CG and JT; 49.4% were considered to have artefactually raised BMD due to degenerative changes (Table 1); 9.7% of DXA scans had evidence of other artefacts to explain their high BMD or were unverifiable. Of the remaining cases, 5.8% did not meet our Z-score threshold for defining HBM. After screening DXA databases at the other three NHS centres, local investigators identified a further 86 HBM cases as meeting our entry criteria. The final prevalence of HBM is shown in Table 2. When results from searching Hologic and Lunar databases were combined, the overall prevalence of HBM was 0.181%. Indication for DXA referral was examined in a subgroup of 22% of scans acetylcholine at the largest centre in Hull (Online Resource Table 1). The most common indication was a suspicion of

osteoporosis based upon height loss or low trauma fracture (28.8%), which also accounted for 35.3% of indications for DXAs which were found to have a T-/Z-score ≥ +4. Treatment monitoring prompted 17.1% of overall referrals but only accounted for 4.8% of referrals for DXA in individuals found to have high BMD. Table 1 Causes of a raised T- or Z-score of +4 or greater on DXA scans screened and inspected from ten NHS centres Causes of T-/Z-score ≥ +4 Number Percent High bone massa 520 35.1 Degenerative disease/osteoarthritis/scoliosis 732 49.4 Generalized sclerosis but below threshold to qualify as index casea 86 5.8 Surgical metalwork 21 1.4 Paget’s disease 21 1.4 Artefact, cause undetermined 19 1.3 Metastatic disease 16 1.1 Ankylosing spondylitis 15 1.