Sarcopenia Indicators as Predictors of Functional Decline and Need for Care among Older People.

OBJECTIVES: Sarcopenia is associated with poor health outcomes. We examined the relative roles of muscle mass, strength, physical performance and obesity as health predictors among older sarcopenic people. DESIGN AND PARTICIPANTS: This prospective study examined community-dwelling people aged 75+ (N=262). SETTING: Porvoo Sarcopenia and Nutrition Trial. MEASUREMENTS: We collected demographic data and medical history by postal questionnaire including RAND-36 at baseline and at four years and measured BMI, Short Physical Performace Battery (SPPB), hand-grip strength, cognition and two surrogate measures of muscle mass; the Single Frequency Skeletal Muscle Index (SF-SMI) and the Calf Intracellular Resistance Skeletal Muscle Index (CRi-SMI). RESULTS: Adjusted for age and gender, independent outdoors mobility was predicted positively by baseline physical functioning scores in RAND-36 (p<0.001), the SPPB (p<0.001), the two-minute step test (p<0.001), and grip strength (p=0.023), as well as CRi-SMI (p<0.001). However, the prediction was negative in BMI (p<0.001) and the Charlson co-morbidity Index (p= 0.004). Similar associations were found when the physical component RAND-36 was used as an outcome measure. The use of home care was predicted by high co-morbidity (p=0.057) and low scores in RAND-36 (p<0.001), SPPB (p<0.001) and the two-minute step test (p<0.001), and low CRi-SMI (p<0.001). CRi-SF was a more consistent predictor than SF-SMI, which was partly masked by BMI. Controlled for age, gender and comorbidity, a 10% difference in CRi-SMI was associated with a 4% higher probability (p=0.019) of independently living at home, whereas the respective figures for SF-SMI and BMI were -18% (p=0.098) and -14% (p=0.088). CONCLUSIONS: In contrast to SF-SMI, high CRi-SMI appeared to indicate good prognosis and less need of care, independently of BMI.