Cross-sectional Relationship Between Haemoglobin Concentration and Measures of Physical and Cognitive Function in an Older Rural South African Population

J Epidemiol Community Health. 2018 Sep;72(9):796-802. doi: 10.1136/jech-2018-210449. Epub 2018 Apr 21.

Abstract

Background: Age cohort differences in haemoglobin concentrations and associations with physical and cognitive performance among populations of lower income and middle-income countries have not previously been described. We examined the association between these factors among older men and women in rural South Africa.

Methods: We analysed cross-sectional data from a population-based study of rural South African men and women aged 40 and over (n=4499), with data drawn from questionnaire responses, a cognitive battery, objective physical function tests and blood tests. Anaemia was defined as a haemoglobin concentration <12 g/dL for women and <13 g/dL for men. We related haemoglobin concentrations to each of age, grip strength, walk speed and a latent cognitive function z-score for men and women separately. We used unadjusted correlations and linear models to adjust for comorbidities and inflammation.

Results: In total, 1042 (43.0%) women and 833 (40.1%) men were anaemic. Haemoglobin concentrations were inversely correlated with age for men but not for women; in adjusted analyses, haemoglobin was 0.3 g/dL lower per decade older for men (95% CI 0.2 to 0.4 g/dL). In adjusted analyses, haemoglobin concentration was independently associated with grip strength in women (B=0.391, 95% CI 0.177 to 0.605), but this did not reach significance in men (B=0.266, 95% CI -0.019 to 0.552); no associations were observed between haemoglobin levels and walk speed or cognitive score.

Conclusions: Anaemia was prevalent in this study population of middle-aged and older, rural South African adults, but in contrast to high-income countries, it was not associated with poor physical or cognitive function. Our findings need to be replicated in other populations.

Keywords: ageing; chronic di; functioning and disability; international hlth; physical function.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Cognition*
  • Cross-Sectional Studies
  • Female
  • Hemoglobins / analysis*
  • Humans
  • Male
  • Middle Aged
  • Physical Fitness*
  • Rural Population
  • South Africa

Substances

  • Hemoglobins