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Keywords:

  • chronic renal insufficiency;
  • aging;
  • anemia;
  • hyperkalemia;
  • acidosis;
  • hyperphosphatemia

Objectives

To determine whether elderly adults with a low glomerular filtration rate (GFR) are at risk for anemia, hyperkalemia, acidosis, and hyperphosphatemia.

Design

Retrospective study.

Setting

Veterans Affairs Medical Center.

Participants

Thirteen thousand eight hundred seventy-four veterans aged 65 and older with chronic kidney disease (CKD) and a GFR between 15 and 60 mL/min per 1.73 m2. Their average age was 79.

Measurements

Anemia was defined as a hemoglobin level of less than 10 g/dL, hyperkalemia as a potassium level greater than 5.5 mEq/L, acidosis as a bicarbonate level of less than 21 mEq/L, and hyperphosphatemia as a phosphorus level greater than 4.6 mg/dL. Multivariable logistic regression was used to evaluate whether age modifies the effect of low GFR on metabolic complications by including an interaction term between age and GFR in each model.

Results

The average GFR of participants was 46.5 mL/min per 1.73m2, 3.1% had anemia, 2.5% hyperkalemia, 2.3% acidosis, and 4.4% had hyperphosphatemia. Lower GFR was associated with higher rates of metabolic complications across all age groups (odds ratio per 5-mL/min per 1.73 m2 decrease in GFR in multivariable models was 1.21 for anemia, 1.26 for hyperkalemia, 1.45 for acidosis, and 1.72 for hyperphosphatemia). There was no significant interaction between age and GFR in models including only age and GFR or in multivariable models (P-values for age by GFR interaction term: 0.66 for anemia, 0.19 for hyperkalemia, 0.54 for acidosis, and 0.22 for hyperphosphatemia).

Conclusion

Elderly adults with CKD are at risk for anemia, hyperkalemia, acidosis, and hyperphosphatemia; age does not modify the relationship between GFR and development of metabolic complications. Elderly adults with low GFR should be monitored for metabolic complications, regardless of age.