fection such as coronary heart disease and diabetes are increasing in incidence as patients live 24211709 longer. This is compounded by an increase in life-expectancy in the developed world that is shifting the patterns of age-related disease. Hip fracture already constitutes a major cause of rising morbidity in this setting and the incidence has increased by 25% from 1990 to 2000 and is projected to increase by 300% by 2050 by the World Health Organisation. There is a high incidence of osteoporosis in most HIV cohorts compared to the general population. This may be explained by an increased incidence of risk factors for osteoporosis in MedChemExpress Digitoxin people living with HIV, direct effects of HIV including immune activation, the effects of HIV 
therapy on osteoclast and osteoblast activity or through indirect mechanisms such as the effect on vitamin D metabolism, and the association of HIV disease with insulin resistance and lipodystrophy. HAART has been found to be associated with 23033494 a reduced bone mineral density in most studies, but others have not found a significant effect. Most antiretroviral drugs have the potential to interfere with bone metabolism but some drugs, or drug classes have been associated with greater BMD loss than others, notably the protease inhibitor class and tenofovir. A meta-analysis of 12 studies showed a 1.6 times greater loss in BMD for those on a PI regimen compared to those on HAART without a PI. Tenofovir, a nucleoside reverse transcriptase inhibitor, has been associated with reduced BMD in people with HIV, possibly through proximal tubule toxicity. An increased incidence in fractures has already been reported in people with HIV, compared to uninfected cohorts and may herald a future trend. Our study addresses the relative contribution of risk factors for osteoporotic fractures present in a large ethically mixed cohort of male and female patients with HIV infection. This will help inform an evidence-based approach to monitoring, screening and management of fragility fractures in this chronic infectious disease. clinics, but not from specialist clinics, to avoid selection bias. The protocol was approved by The Bromley PCT Research Ethics Committee and is registered with ClinicalTrials.gov Identifier: NCT01669954. Controls were recruited from the Twins-UK register at the Department of Twin Research, King’s College London. This register has >6,000 twin pairs who are studied regularly for healthrelated parameters, including bone health. One individual from each twin pair whose visits had been broadly contemporaneous with the HIV infected patients was selected. The twin controls had been recruited from around the United Kingdom, and had DXA scanning between 1998-2000 as part of their assessment. Twins are comparable to singletons for a variety of health and lifestyle traits. It was recognised that it would be impossible to match for ethnicity, as there were very few non-Caucasian volunteers within TwinsUK. There were many fewer males in TwinsUK, but it was possible to select an age-matched group of males who had had dual energy X-ray absorbtiometry scans and relevant biochemistry. Bone biochemistry and DXA scan, were a routine part of the twin cohort measurements, but testosterone, sex hormone binding globulin and vitamin D levels were not routinely measured among the control group. Assessments Questionnaires were completed by cases and controls and included the risks for fragility fracture, and HIV associated history where appropriate.