Prevalence and Sex Difference of Lumbar Disc Space Narrowing in Elderly Chinese Men and Women: Osteoporotic Fractures in Men (Hong Kong) and Osteoporotic Fractures in Women (Hong Kong) Studies

OBJECTIVE: Osteoporotic Fractures in Men (Hong Kong) and Osteoporotic Fractures in Women (Hong Kong) represent the first large-scale prospective population-based studies on bone health in elderly (age≥65 years) Chinese men (n=2,000) and women (n=2,000). We undertook the current study to investigate the prevalence of lumbar disc space narrowing in these subjects, and to identify the potential relationship between disc space narrowing and sex, bone mineral density (BMD), and other demographic and clinical data. METHODS: On lumbar lateral radiographs, L1/L2-L4/L5 disc space was classified into 4 categories: 0=normal; 1=mild narrowing; 2=moderate narrowing; 3=severe narrowing. We compared demographic and clinical data between subjects with and those without total disc space narrowing scores≥3. RESULTS: Disc space narrowing was more common in elderly women than in elderly men. The mean±SD disc space narrowing score for the 4 discs was 2.71±2.21 for men and 3.08±2.50 for women (P<0.0001). For the 3 age groups of 65-69 years, 70-79 years, and ≥80 years, the average disc space narrowing score increased with increasing age in both men and women, and to a greater degree in women than in men. The average disc space narrowing score differences between women and men were 0.12, 0.40, and 0.90, respectively, in the 3 age groups. For both men and women, a disc space narrowing score≥3 was associated with older age, higher spine and hip BMD, low back pain, and restricted leg mobility. CONCLUSION: The prevalence and severity of disc space narrowing are higher in elderly women than in elderly men. With increasing age, disc space narrowing progresses at a greater rate in women than in men. A disc space narrowing score≥3 is associated with higher spine and hip BMD.