HIV infection: an important cause of secondary osteoporosis

The devastating mortality associated with HIV infection has been dramatically reduced by highly active antiretroviral therapies (HAART). However, this has led to increasing numbers of HIV-infected patients living with comorbidities, including metabolic diseases. Low bone mass and osteoporosis were implicated as consequences of HAART approximately 10 years ago but fracture data in HIV-infected populations are rare. A well-characterized cohort of HIV-infected adults attending one UK centre for outpatient care was surveyed [1]. Trained nurses administered a questionnaire which enquired about previous fractures, demographic factors, lifestyle factors, diet and exercise, exposure to glucocorticoids and other drugs affecting bone mineral and HIV factors. Exposure to HAART, stage of HIV infection and status of viral load, CD4 counts were collated.

In total, 1050 HIV infected adults were surveyed. 859 (82%) responded. Mean age of respondents was 42.7 years. 87% were Caucasian and 90% were male. Mean duration of HIV infection was 6 years and 76% were current users of ARVs. Overall, 125 subjects (119 [15%] men and 6 women [7%]) reported 200 fractures. 65 respondents reported fractures of their distal forearm, 6 reported hip fractures and 2 vertebral fractures. In total, 57% of the 200 reported fractures occurred under age 25 years, with the peak age 7 to 12 years. However, 33 fractures (26%) occurred among respondents aged >40 years and 8 (24%) among those aged >50 years. The second peak of fractures occurred at the distal forearm (n=6, mean age 48.2 years) and there was 1 hip fracture (age 46 years). 15% of those who sustained a fracture at age >40 years had been exposed to oral glucocorticoids as compared with 9% of those who had not fractured.

These results suggest a traditional bimodal distribution of fracture in this population. The first peak occurs in childhood/adolescence and is maximal aged 7 to 12 years, a second peak of fracture aged >40 years at sites with a high proportion of trabecular bone (distal forearm, vertebrae). This peak is seen much earlier than in non-HIV- infected adults but affects similar sites to those of traditional osteoporotic fractures. Fracture may be a consequence of low bone mass in HIV infection. If these data are replicated, HIV may become one of the most important causes of secondary osteoporosis worldwide.

1. Walker-Bone K et al. Presented in Abstract form at the ACR Meeting, 2010