In the Journals

Medicaid patients often prescribed unnecessary antimicrobials

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May 7, 2014

Researchers reported that slightly more than half of adult Medicaid patients with acute respiratory tract infections were prescribed antimicrobial drugs in 2007, although antimicrobials are not recommended in these cases.

Unnecessary [antibiotic] use contributes to emergence of antimicrobial drug-resistant bacteria, an emerging public health crisis that contributes to greater rates of illness and death and economic costs as high as $4 billion per year,” the researchers wrote.

In the study, the researchers culled data from the 2007 Medicaid Analytic Extract files to identify patients aged 21 years and older across 40 states who were diagnosed with acute respiratory tract infections (ARIs) from Jan. 1 to Dec. 24, 2007.

ARIs were defined as colds, acute upper respiratory infections (URIs) at multiple locations or acute bronchitis.

The study’s main outcome variable was the existence or lack of a claim for an antimicrobial drug prescription resulting from the patient’s diagnosis. Antimicrobials were defined as drugs in the following classes: cephalosporins, penicillins, sulfonamides, macrolides (including azalides) lincosamides, tetracyclines and quinolones. Because Medicaid drug claims do not specify a diagnosis that is linked to a specific prescription, the researchers presumed the drug was prescribed for an ARI if it was filled on the same date or within 4 days of when the patient presented with an ARI.

The investigators used logistic regression analyses, adjusting for state-level clustering, to determine factors related to antimicrobial drug prescriptions for ARI doctor visits. Among the covariates were patient age, sex, race and Prescription Drug Hierarchical Coexisting Condition score, and county-level covariates.

The researchers found that in 2007, 194,874 adults receiving Medicaid had at least one doctor visit in which ARI was diagnosed in the absence of other associated secondary diagnoses for which treatment with antimicrobials would have been appropriate. Subsequent to this visit, approximately 52% of patients filled an antimicrobial drug prescription. Macrolides were the antimicrobial medication most commonly prescribed (27.8%), followed by penicillins (12.3%).

The likelihood of filling antimicrobial drug prescriptions for an ARI were significantly lower in older adults, men and non-white patients. Those with acute bronchitis were considerably more likely to fill their prescriptions than those with a cold or URI (69% vs. 40%; OR=3.32; 95% CI, 2.78-3.95). Patients who lived in counties with the highest concentration of primary care physicians were less likely to fill an antimicrobial drug prescription than patients who lived in a county with the fewest physicians (48.2% vs. 56.8%; OR=0.76, 95% CI, 0.66-0.88). The odds of filling antimicrobial prescriptions were lower for patients in states that were involved in the CDC’s Get Smart campaign from 2002 to 2006 (n=33) than for those in non-participating states (50.7% vs. 57.7%; OR=0.74, 95% CI, 0.62-0.88).

“In 2007, more than half of Medicaid patients filled a prescription for antimicrobial drugs for an ARI, despite essentially no evidence of efficacy for this use,” the researchers wrote. “The substantially higher use of antimicrobial drugs for acute bronchitis than for colds or other URIs raises the need for effective interventions to further support physician decision making. Examples of such interventions include active clinician education strategies, which are more effective than passive education strategies.”

Disclosure: The researchers report no relevant financial disclosures.

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