Homocysteine as a predictive factor for hip fracture in elderly women with Parkinson’s disease

Purpose Incidence of hip fractures among elderly patients with Parkinson’s disease is high. Recent studies have found that levodopa induces hyperhomocysteinemia in Parkinson’s disease. Hyperhomocysteinemia is considered to be a risk factor for osteoporotic fractures in elderly men and women. Very high plasma homocysteine levels are a feature of homocystinuria, characterized by the early onset of osteoporosis. To determine the association between plasma homocysteine concentration and the risk of hip fracture in Parkinson’s disease patients receiving levodopa, we prospectively studied a cohort of elderly women with Parkinson’s disease. Methods We studied 199 elderly women with Parkinson’s disease receiving levodopa therapy, from whom blood samples had been obtained to measure plasma homocysteine. Age-adjusted incidence rates of hip fractures were calculated for quartiles of plasma homocysteine concentrations. Cox proportional-hazard regression was used to calculate hazard ratios for quartiles of homocysteine values. Results The mean duration of follow-up was 4.9 years. Hip fractures occurred in 66 patients. The age-adjusted incidence rates per 1000 person-years for hip fractures, from the lowest to the highest quartile of plasma homocysteine levels, were 1.59 (95% confidence interval [CI], 1.01-2.24), 1.57 (95% CI, 0.98-2.19), 1.21 (95% CI, 0.61-1.72), and 26.98 (95% CI, 16.48-37.24). The risk of hip fractures was greater in the highest quartile than that in the lowest, and the risk was almost 2.4 times higher. Conclusion These findings suggest that the homocysteine concentration is an important risk factor for hip fractures in Parkinson’s disease patients receiving levodopa.