Association of Age and Body Mass Index with Bone Mineral Density in a Hospital-Based Cohort from Karachi, Pakistan

Objective: To investigate the correlation of bone mineral density (BMD) with age and body mass index in patients undergoing DEXA scans. Methodology: This was a retrospective observational study conducted at the Medicare Cardiac and General Hospital, Karachi, crossing over the period from 8th September 2022 to September 2023. The study retrospectively analyzed the data of 154 patients who had undergone DEXA scans. Demographic details included age and sex, while anthropometric measurements included height, weight, and BMI. T-scores of both the lumbar spine and femoral neck were noted. Patients with systemic bone disorders, cancer, kidney diseases, and those on hormonal therapy or smoking were excluded. Data analyses were done on SPSS version 25, applying descriptive statistics and Spearman correlation tests; p-values less than 0.05 were considered significant. Results: The mean age was 60.6 ± 10.1 years, while the mean BMI was 30.6±6.27 kg/m². For the T-score, the mean was -1.023± 1.66 at the lumbar spine and -.908±1.2 at the femur. The lumbar BMD status was significantly associated with age p = 0.001, whereby older patients have higher proportions of osteopenia and osteoporosis. No significant associations were noted between either BMI or gender and BMD status; however, Spearman correlation demonstrated a weak negative association of age with BMD in both sites and a positive correlation with BMI, especially in the femoral neck (r = 0.285). Conclusion: With increasing age, there was a strong association with decreasing lumbar BMD, whereas increasing BMI showed a protective effect on the femoral BMD. Routine osteoporosis screening is essential for early detection and prevention, especially in people above 50 years. Lifestyle and hormonal factors should be included in further studies to strengthen the evidence.