Objective
To investigate the scale of antimicrobial prescribing without a
corresponding visit, and to compare the attributes of patients who received
antimicrobials with a corresponding visit to those who did not have a
visit.
Design
Retrospective cohort
Methods
We followed 185,010 Medicare patients for one year after an acute
myocardial infarction. For each antimicrobial prescribed, we determined if
the patient had an inpatient, outpatient or provider claim in the 7 days
prior to the antimicrobial prescription being filled. We compared the
proportions of patient characteristics for those prescriptions associated
with a visit and without a visit (i.e., phantom prescriptions). We also
compared the rates at which different antimicrobials were prescribed without
a visit.
Results
We found that of 356,545 antimicrobial prescriptions, 14.75%
had no evidence of a visit in the week prior to the prescription being
filled. A higher percentage of patients without a visit were identified as
white (p<0.001) and female (p<0.001). Patients without a
visit had a higher likelihood of survival and fewer additional cardiac
events (AMI, cardiac arrest, stroke, all p<0.001). Among the
antimicrobials considered, amoxicillin, penicillin, and agents containing
trimethoprim and methenamine were much more likely to be prescribed without
a visit. In contrast, levofloxacin, metronidazole, moxifoxacin, vancomycin,
and cefdinir were much less likely to be prescribed without a visit.
Conclusions
Among this cohort of patients with chronic conditions, phantom
prescriptions of antimicrobials are relatively common and occurred more
frequently among those patients who were relatively healthy.