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Older Adult Kidney Function Assessment and Rounding Creatinine Led to Medication Dosing Error

Nguyen, Timothy PharmD, BCPS, FASCP1,*; Foster, Yanique PharmD2; Cekaj, Shpres PharmD2

doi: 10.1097/MJT.0000000000000568
Systematic Review and Clinical Guidelines

Background/Areas of Uncertainty: Kidney function assessment in older adults can be unreliable because of many factors, and inaccurate assessment can lead to medication dosing error. Practitioners may have adopted the method of rounding creatinine to an arbitrary number 1.0 because of change in muscle mass and age-related change. This has in fact proven to cause more harm than good, potentially leading to underdosing of many medications.

Data Sources: A literature search performed using PubMed with the following key words (rounding serum creatinine, rounding serum creatinine AND pharmacist or pharmacy, rounding serum creatinine AND doctor or physician or healthcare, rounding serum creatinine AND kidney function) with no restrictions (dates or any other requirement).

Results: From the PubMed results, articles related to rounding of serum creatinine (Scr) and kidney function assessments were identified and reviewed. Most studies were retrospectives, 1 cross-sectional, 1 meta-analysis, and others were unidentified. These studies included various ways of estimating kidney functions (Tc99m DTPA clearance, Cockcroft–Gault creatinine clearance, 24-hour urine collection, Modification of Diet in Renal Disease, Chronic Kidney Disease-Epidemiology Collaboration), used various weights (actual body weight, ideal body weight, adjusted body weight), and most studies used 1.0 for rounding up Scr (other studies used 0.8 and 0.85). There was no associated relationship found as related to practicing professions (pharmacists vs. physician) to the practice of rounding Scr.

Conclusions: All studies yielded inaccurate kidney function upon rounding of Scr and leading to medication dosing error. All studies suggested against rounding Scr when assessing kidney function in older adults.

1Arnold & Marie Schwartz College of Pharmacy and Health Sciences, LIU Pharmacy, Brooklyn, NY; and

2LIU Pharmacy, Brooklyn, NY.

Address for correspondence: Long Island University, 75 DeKalb Avenue, Brooklyn, NY 11201. E-mail:

The authors have no conflicts of interest to declare.

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