Seniors on polypharmacy make more dosing errors over time

Elderly adults taking multiple medications tend to make more and more dosing mistakes over time, a new study has found.

Enrolling in 2008, researchers followed 900 elderly adults (aged 55–74 years at baseline) for 9 years. At baseline, participants were given a standardized seven-drug regimen and were asked to demonstrate how they would take them over a 24-hour period. Dosing errors were recorded as a primary outcome, along with regimen consolidation.

A total of 303 participants (mean age, 62.6 years; 72.9 percent female) completed all medication dosing exercises over the 9-year follow-up period. At baseline, 98 percent of the sample had no cognitive impairment, which dropped slightly to 96 percent by the final follow-up, during which time one participant developed severe cognitive impairment.

At baseline, participants made an average of 2.9 dosing errors out of a total 21 potential errors. This climbed to a mean of 5.0 errors at the final follow-up, corresponding to a statistically significant increase (p<0.001). During both time points, spacing errors were the most prevalent (82.5 percent), followed by dose (33 percent) and frequency (16.8 percent) errors.

Multivariate analysis identified limited health literacy (p=0.01), meaningful cognitive decline (p=0.01) and a greater number of chronic conditions (p=0.01) as significant risk factors for changes in dosing errors over 9 years. Such errors at baseline were similarly predictive (p<0.001).