Hilmer et al describe the total drug burden (TDB), also referred to as the drug burden index (DBI). It is intended to describe the burden on a geriatric patient associated with anticholinergic and sedative drugs. The authors are from the National Institute on Aging, University of Florida and University of California at San Francisco.
Patient selection: geriatric adult capable of performing physical measures
Drugs: those with anticholinergic or sedative properties. A drug having both effects was classified as anticholinergic.
burden for an anticholinergic drug =
= (daily dose) / ((daily dose) + (minimum approved daily dose))
burden for a sedative drug =
= (daily dose) / ((daily dose) + (minimum approved daily dose))
burden for all anticholinergic drugs =
= SUM(burden for all anticholinergic drugs)
burden for all sedative drugs =
= SUM(burden for all sedative drugs)
total drug burden =
= (burden for all anticholinergic drugs) + (burden for all sedative drugs)
Interpretation:
• minimum score: 0, which indicates that the patient is not taking any anticholinergic or sedative drug.
• maximum score: depends on total number of drugs being taken and the dose.
• A higher drug burden index was associated with worse physical function.
When score is analyzed:
(1) If the dose that the patient is taking the minimum dose approved by the FDA, then the burden is 0.5.
(2) A burden less than 0.5 would probably be subtherapeutic (exception: patient very sensitive to drug).
(3) The maximum value for the burden for a drug would be very close to 1. A person taking 10 times the minimum dose would have a burden of 0.91.
