Inappropriate drug dosage adjustments in patients with renal impairment.

BACKGROUND

The aim of this study was to determine whether appropriate dosage adjustments were made in patients with renal impairment discharged from the Department of Internal Medicine and to evaluate a possible role for family medicine physicians in reducing the number of inadequate drug dosages.

METHODS

The study included all patients discharged from the Department of Internal Medicine. Data regarding serum creatinine levels, age, sex and prescribed drugs and their dosage were collected from the patients' medical records and discharge letters after discharge from hospital. We calculated the estimated glomerular filtration rate (GFR) using the abbreviated MDRD equation. Drug dosage adequacy was controlled in the patients with GFR less than 60 ml/min per 1.73 m2.

RESULTS

At the time of discharge from the hospital, 161 of 712 patients (22.6%) had estimated GFR <60 ml/min per 1.73 m2. These patients were prescribed 874 drugs, which amounted to 5.43 per patient. Dosage adjustment according to renal function was necessary for 171 prescriptions (19.6%). This adjustment was performed adequately in 81 cases (47.4%) and inadequately in 90 cases (52.6%). Digoxin metformin and the combination of ACE inhibitors and spironolactone amounted to 65.6% of the inadequate prescriptions. There were significantly more incorrect drug dosages in women.

CONCLUSION

Drug dosage in patients with renal impairment can be improved. Since a computerized dynamic alert system is not available in our hospital the role of family medicine physicians is significant in reducing the number of inadequate drug dosages at hospital discharge.