Switch From Tenofovir to Raltegravir for Low Bone Mineral Density

Inclusion Criteria: 1. provision of written, informed consent 2. HIV-infected adults at least 18 years of age 3. receiving stable ART including TDF and a r/PI for the previous 6 months 4. no prior PI genotypic resistance or known replication of HIV in patients receiving a PI 5. plasma HIV RNA \< 50 copies/ml for at least the previous 3 months 6. spine or neck of femur t-score ≤ -1.0 (i.e. WHO-defined osteopenia) measured by dual energy x-ray absorptiometry (DEXA) Exclusion Criteria: 7. participation in any other clinical trial (unless approved by the study PI) 8. use of TDF for previously active chronic hepatitis B infection 9. receiving or requiring therapy for low BMD (including prior fragility fracture) 10. using oral corticosteroids or inhaled fluticasone 11. virological failure on, or intolerance to, RAL 12. contra-indication to RAL therapy (see appendix 2) 13. breast-feeding 14. pregnancy 15. secondary, endocrinological cause of low BMD:25-hydroxy vitamin D deficiency, hypogonadism: a)symptomatic b)asymptomatic defined by total testosterone \> 25% below lower limit of reference range and/or luteinizing hormone \> 2 x upper limit of normal (ULN),untreated hypothyroidism or hyperparathyroidism according to local reference ranges