Kidney function decline is associated with an accelerated increase in plasma homocysteine in older adults: a longitudinal study.

Few studies have been conducted to investigate the association of kidney function decline with the trajectories of homocysteine (Hcy) over time, using repeated measurements. We aimed to investigate the association of kidney function with changes in plasma Hcy levels over time. Data were collected from the Rugao Longevity and Ageing Study. In detail, plasma Hcy and creatinine levels were measured in both waves (waves 2, 3 and 4) during the 3·5-year follow-up (n 1135). Wave 2 was regarded as the baseline survey. The estimated glomerular filtration rate (eGFR) was calculated based on creatinine. Subjects were categorised into four groups according to quartiles of eGFR at baseline. Linear mixed-effect models were used to investigate the association of eGFR with subsequent plasma Hcy levels. The mean eGFR at baseline was 90·84 (sd 11·42) ml/min per 1·73 m2. The mean plasma Hcy level was 14·09 (sd 6·82) at baseline and increased to 16·28 (sd 8·27) and 17·36 (sd 10·39) μmol/l during follow-ups. In the crude model, the interaction between time and eGFR at baseline was significant (β = -0·02, 95 % CI -0·02, -0·01, P = 0·002). After adjusting for confounding factors, a significant relationship remained (β = -0·02, 95 % CI -0·02, -0·01, P = 0·003), suggesting that kidney function decline at baseline was associated with a faster increase in Hcy levels. Kidney function decline is associated with a more pronounced increase in plasma Hcy levels. Further studies with longer follow-up periods and larger sample sizes are needed to validate our findings.