So what does this mean? Are nephrologists watching the eGFR and deciding to start earlier based on this number alone? I think not. In one way, this shows the limitations of using eGFR in epidemiological studies, particularly in the very elderly and in those with very low GFRs. The patients who withdrew from dialysis were more likely to have dementia, cancer and were older. Also, apart from age, the factor with the highest HR for withdrawal was a BMI of less than 18. This suggests that using creatinine to estimate eGFR may have overestimated GFR in these patients because of a low muscle mass. It would be interesting to know how well their MDRD eGFRs correlated with their true GFRs.
The outcomes for renal replacement therapy in very elderly populations is poor and the higher rate of withdrawal may reflect poor patient choice – should these patients have been started on dialysis in the first place? This is an interesting study and it highlights the importance of proper discussion with patients and families about the consequences of dialysis initiation.