Sarcopenia and mortality in Indigenous and non-Indigenous New Zealand octogenarians-the LiLACS NZ cohort study.

Purpose: As the population is ageing, age-related vulnerability to chronic infirmity has become of greater concern. Sarcopenia, low muscle strength and mass, is a major contributor to infirmity. Both sarcopenia and hand grip strength (HGS) are known to predict mortality in older people. This paper investigates the impact of ethnicity on this relationship in New Zealand octogenarians.

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 with follow-up mortality data for over twelve years and had a median survival period of 6.02 years, 251 Māori and 374 non-Māori had sufficient data to be included in modelling. Survival analysis (Cox regression) assessed the association between HGS or probable sarcopenia (defined using HGS) and mortality, separately by ethnicity (Māori, non-Māori) and sex.

Results: Hand grip strength was a predictor of mortality for non-Māori men (age-adjusted hazard ratio, aHR, per 1 kg increase in HGS, 0.93, 95% CI: 0.91-0.96) but not for women or Māori men. Probable sarcopenia was associated with an increased hazard of mortality among all groups, but the effect was statistically significant for non-Māori (men 1.97, 1.39-2.79; women 1.49, 1.08-2.06) and not Māori (men 1.55, 0.97-2.48; women 1.36, 0.79-2.34).

Conclusion: Hand grip strength, either as a continuous variable or to identify probable sarcopenia, remains an important indicator with high clinical utility in advanced age. However, its utility may need to be re-examined for Indigenous populations.