Prevalence of sarcopenia based on different diagnostic criteria using DEXA and appendicular skeletal muscle mass reference values in an Italian population aged 20 to 80.

OBJECTIVE: To identify the mean values and percentiles for ASMM (appendicular skeletal muscle mass) and the prevalence of sarcopenia, in terms of muscle mass reduction, using different cutoffs in a European population.
DESIGN: A retrospective analysis on the dataset from a multicenter study on apparently healthy Italian adults conducted between 1999 and 2002. A significant muscle mass loss, necessary to diagnose sarcopenia, was defined in 3 different ways: (1) by subtracting 2 SDs from the mean ASMM index (ASMMI) of a young adult population (20-39 year-olds), as in the Rosetta study and the NHANES survey; (2) by calculating the 15th percentile of the distribution of our young population, corresponding to about 1 SD below the mean ASMMI; (3) by calculating the 20th percentile of the distribution of the ASMMI (as in the Health ABC study) of an elderly population.
SETTING: Five centers for the diagnosis and treatment of osteoporosis in various parts of the country (Padova, Verona, Parma, Roma, Napoli). PARTICIPANTS: Participants were 1535 volunteers (1208 women and 327 men) aged 20 to 80 years, drawn from among staff members, university students, lay people contacted by word of mouth, and patients presenting spontaneously for osteoporosis screening. MEASUREMENTS: Body weight and height were measured for all participants. Body composition was assessed by DEXA, and the ASMMI was calculated as the ASMM divided by body height in meters squared.
RESULTS: Both men's and women's lean mass in the arms and ASMM were highest in the young group and became lower in older age. In men, the ASMMI dropped gradually from age 20 to 29 to age 60 to 69, then remained stable in the oldest group. In women, the ASMMI gradually increased from age 20 to 29 to age 60 to 69, then dropped among the 70- to 80-year-olds. Based on the 15th percentile of the ASMMI for our young adult reference population, the cutoffs for sarcopenia were 7.59 kg/m(2) in men and 5.47 kg/m(2) in women; if the 20th percentile of the ASMMI in our elderly subjects (>65 years) was considered, the cutoffs were 7.64 kg/m(2) in men and 5.78 kg/m(2) in women. Applying the different diagnostic criteria to the those older than 65, the prevalence of sarcopenia ranged from 0% to about 20% in both genders.
CONCLUSION: The 15th percentile (or 1 SD below the mean) of the ASMMI of our young adults, and the 20th percentile of this index for an elderly reference population proved more effective in identifying cases of sarcopenia than subtracting 2 SD from the mean ASMMI of a young adult population.