Hand grip strength and loss of independence in Indigenous and non-Indigenous New Zealand octogenarians-the LiLACS NZ cohort study

BACKGROUND: The number of people losing their independence is increasing as the population ages. Sarcopenia, low muscle strength and mass, and hand grip strength (HGS) are known to predict reduced independence in people in their seventies. This paper investigates these relationships in New Zealand octogenarians, including Indigenous Māori. METHODS: This study used data from Life and Living in Advanced Age: A Cohort Study in New Zealand (LiLACS NZ), which recruited 421 Māori and 516 non-Māori in 2010-2011. The Nottingham Extended Activities of Daily Living (NEADL) scale measured independence. Participants were classified by ethnicity (Māori or non-Māori) and sex into high, medium or low independence trajectory groups based on their six annual NEADL scores using group-based trajectory modelling. The associations between HGS or probable sarcopenia (a binary measure of HGS) and independence trajectory group (high, medium, low) were tested separately by ethnicity and sex in multinomial logistic regression models. RESULTS: Hand grip strength was inversely associated with low (versus medium) independence trajectory among Māori women, non-Māori women and non-Māori men, adjusting for age, comorbidities and cognition (adjusted odds ratio, aOR, 0.84 (95% CI 0.72, 0.97), 0.86 (0.77, 0.96) and 0.90 (0.81, 0.99), respectively). Similar associations were seen for probable sarcopenia and independence trajectory among those three groups, but the effects did not reach statistical significance. CONCLUSIONS: Hand grip strength could be a valuable screening tool to assess independence trajectory in octogenarians, but further study is needed to clarify the effects of indigeneity and sex in this population.