Skeletal muscle mass and risk of death in an elderly population.

BACKGROUND AND AIM: Body mass index (BMI) has a U-shaped relationship with mortality among the elderly, in contrast to the general adult population. Skeletal muscle mass may be more appropriate than BMI for classifying mortality risk among the elderly. We investigated the relationship between skeletal muscle mass and mortality among elderly Chinese persons. METHOD AND RESULTS: A total of 1512 elderly from the Nutrition and Health Survey in Taiwanese Elderly (1999-2000) was enrolled, and the survival status was followed using data from the National Death Registry. The skeletal muscle mass index (SMMI) was calculated by dividing skeletal muscle mass by height in meters squared. The Cox proportional hazard model was used to estimate the association between SMMI and mortality. During the follow-up (average time: 7.9 years), one-third elderly died (n = 506) by any cause and 25% of them was cardiovascular mortality (ICD-9-CM: between 390 and 459). The total mortality and cardiovascular mortality were 4.23 and 1.07 per 100 person-years. Elderly participants with the lowest SMMI had the highest total mortality and cardiovascular mortality among the four quartiles (6.72, 3.76, 3.25 and 3.50 per 100 PY for total mortality; 1.81, 0.76, 0.87, 0.93 for cardiovascular mortality). Those with a low (1st quartile) SMMI had a 2-fold increase in total mortality (1.96; 1.63-2.35) and cardiovascular mortality (2.16; 1.51-3.08) risk compared to those with a normal [2nd, 3rd, or 4th quartile] SMMI. CONCLUSIONS: The threshold relationship between SMMI and mortality is contrast to the reverse J-shaped relationship between BMI and total mortality. Therefore, skeletal muscle mass measurement may be considered with a high priority to identify elderly individuals with a high mortality risk.

Hyperuricemia and incident atrial fibrillation in a normotensive elderly population in Taiwan.

BACKGROUND AND AIM: Atrial fibrillation (AF) is an important cardiovascular disease in the elderly. The association between hyperuricemia and AF is unclear. Therefore, we aimed to investigate the prospective relationship between uric acid and development of AF in a nationally representative cohort of elderly people. METHODS AND RESULTS: A total of 1485 elderly people (age ≥ 65 yrs) from the Elderly Nutrition and Health Survey in Taiwan (1999-2000) were without AF on "electrocardiography" at baseline. Incident AF events (International Classification of Diseases, Ninth Revision, Clinical Modification, ICD-9-CM: 427.31) were identified using data from the National Health Insurance Dataset. Hyperuricemia was defined as levels of uric acid >7.0 mg/dL in men and 6.0 mg/dL in women. A Cox proportional hazards model was used to evaluate the association between hyperuricemia and incident AF. The follow-up period was from 1999 to 2000 to 2008. During the follow-up period (median: 9.16 yrs), 90 AF events occurred (44 in men and 46 in women). Older age, elevated systolic blood pressure, being an ex-smoker, and high uric acid were positively associated with incident AF. Hyperuricemia was positively associated with incident AF in normotensive (age-adjusted hazard ratio (HR): 2.65 and 95% confidence intervals: 1.05-6.69), but not in (1.20:0.74-1.94) hypertensive individuals (systolic blood pressure ≥130 or diastolic blood pressure ≥85 or using hypertensive medicine). A significant association between hyperuricemia and AF (3.78; 1.24-11.59) remained after adjusting for other potential confounders among normotensive older persons. CONCLUSION: Hyperuricemia is associated with the development of AF in elderly people with normal blood pressure.