[Creatinine clearance and drug prescriptions for the elderly. A study of 419 patients older than 70 years admitted through the emergency department].
BACKGROUND
The incidence of drug-related adverse events increases with age. In approximately 20% of cases, these events necessitate hospitalization. By taking into account the physiological changes associated with aging when prescribing drugs, physicians can prevent some of these events. The objective of this study was to analyze the prescriptions written by general practitioners for elderly patients admitted to the emergency department in relation to the patient's creatinine clearance.


METHODS
Of 968 consecutive patients older than 70 years, 419 underwent a plasma creatinine assay on admission and were included in this study. Creatinine clearance was calculated with Cockcroft's formula. The patients were classified into two groups according to creatinine clearance:<30 mL/min (group I) and >or=30 mL/min (group II).


RESULTS
Creatinine clearance was<30 mL/min in 84 of the 419 patients (group I) and >or=30 mL/min in 335 (group II). Mean age was significantly higher in group I than in group II (87 +/- 6 vs 81 +/- 6 years, p<0.001), as was mean plasma creatinine concentration (113 +/- 23 vs 83 +/- 19 mmol/L, p<0.001), while mean weight was significantly lower (57 +/- 10 vs 69 +/- 13 kg, p<0.001. In group I, 82 drugs with precautions concerning renal function had been prescribed for 69 (82%) patients, and in group II, 331 such drugs for 174 (52%) patients. Of the 82 drugs prescribed in group I that required precaution, 47 (57%) were contraindicated or prescribed at an inappropriate dose in view of the creatinine clearance. Irrespective of pharmacokinetic parameters, the mean number of drugs taken per patient was 5 +/- 2 in group I and 6 +/-2 in group II.


CONCLUSIONS
In prescribing drugs for elderly patients, especially those whose weight is low, careful attention should be paid to renal function.
Service d'Urgence et de Réanimation, Hôpital Bellevue, Saint-Etienne. alain.viallon@univ-st-etienne.fr
Alain
A
Viallon
Pantéa
P
Guyomarch
Olivier
O
Marjollet
Matthieu
M
Belin
Florianne
F
Robert
Christophe
C
Berger
Serge
S
Guyomarch
Jean-Claude
JC
Bertrand
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001835:Body Weight; D003404:Creatinine / Q000378:metabolism*; D011307:Drug Prescriptions / Q000706:statistics & numerical data*; D064420:Drug-Related Side Effects and Adverse Reactions; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007668:Kidney / Q000187:drug effects / Q000502:physiology; D008297:Male; D012189:Retrospective Studies
D003404:Creatinine