Lipid-lowering agents and the risk of hip fracture in a Medicaid population

Area of Science:

• Pharmacovigilance
• Epidemiology
• Geriatric Medicine

Background:

• Previous studies indicated 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) users had half the risk of hip fractures compared to non-users.
• However, these findings may be biased by unmeasured factors related to hyperlipidemia treatment.

Purpose of the Study:

• To compare hip fracture risk between statin users and users of other lipid-lowering agents, aiming to reduce bias from previous studies.
• Investigate potential confounding factors influencing the observed association between statins and fracture risk.

Main Methods:

• A retrospective cohort study was conducted using the Tennessee Medicaid program database from January 1, 1989, to December 31, 1998.
• Included were new users of lipid-lowering drugs and non-user controls, all aged 50+, without severe illnesses, nursing home residence, dementia, or osteoporosis.
• Hip fractures (proximal femur) were the primary outcome, excluding pathological or trauma-related fractures.

Main Results:

• Over 66,690 person-years, 186 hip fractures occurred. Adjusted incidence rate ratios (95% CI) were 0.62 (0.45–0.85) for statin users and 0.44 (0.26–0.95) for other lipid-lowering drug users, relative to non-users.
• Direct comparison showed an adjusted incidence rate ratio of 1.42 (0.83–2.43) for statins versus other lipid-lowering drugs.
• The observed protective effect of statins against hip fractures was not statistically significant when compared to other lipid-lowering agents.

Conclusions:

• The previously observed protective effect of statins on hip fracture risk might be attributable to unmeasured confounding factors.
• These findings suggest that the association between statins and reduced fracture risk needs further investigation to rule out biases.
• The study highlights the importance of considering confounding variables in observational studies of drug effects.