Antibiotic treatment
The pharmacy administrative claims dataset was used to identify study patients who filled a prescription for an antibiotic during their pharyngitis treatment episode. Optum pharmacy data identify the medications received, specifies the date of prescription filling, National Drug Codes, and American Hospital Formulary Service (AHFS) Classification System codes for each medication. We used the AHFS Pharmacologic-Therapeutic classification of antibiotics to create dichotomous variables documenting the antibacterial used by each patient.13 These are categorized under antibacterial including penicillins, cephalosporins (first, second, third, fourth generation cephalosporins), macrolides (first generation and others), tetracyclines, sulfonamides, fluoroquinolones (ciprofloxacin, levofloxacin, moxifloxacin), cephamycin, carbapenems, and β-lactam antibiotics (amoxicillin, amoxicillin/clavulanate, cephalexin, cefuroxime, cefdinir).
Revisits to physician or other provider
Revisits within 28 days were used as the measure of patient outcomes related to testing and filling of an antibiotic prescription for acute pharyngitis. Revisits may also be due to a patient returning for a follow-up, alternative treatment, worsening pharyngitis, or for another ARTI. An ARTI-related revisit also increases total resources used to treat pediatric pharyngitis patients.
Statistical analysis
Logistic regression was used for all 3 analyses conducted in this study. First, we determined the patient and treating physician characteristics that impact the decision to use GAS testing for pharyngitis. Second, we identified those factors that impact the decision to use antibiotic prescriptions among children who were diagnosed with pharyngitis adding in the dichotomous variable indicating if the patient had received a GAS test. Third, we used a logit regression analysis to document if receiving a GAS test and/or an antibiotic impacted the likelihood of a revisit by comparing revisit risk. To estimate the effect of testing and/or antibiotic use, we divided patients into 4 groups based on whether the patient received a GAS test and/or an antibiotic prescription. This specification of the analysis of revisits as an outcome focuses on adherence to HEDIS “test and treat” guidelines10:
- Patients who were not tested yet filled an antibiotic prescription. This decision was likely based on the clinician’s judgment of the patient’s signs and symptoms, and confirmational testing not performed.
- Patients who were not tested and did not fill an antibiotic prescription. Apparently, in the clinician’s judgment the patient’s signs and symptoms were such that the infection did not warrant treatment and the clinical presentation did not necessitate the GAS test to confirm the recorded diagnosis of pharyngitis.
- Patients who were tested and received antibiotic prescription, likely because the test was positive for GABHS.
- Patients who were tested and did not receive antibiotic prescription.
We tested for statistically significant differences in baseline characteristics across these 4 patient groups using t tests for continuous variables and χ2 tests for categorical variables. Odds ratios (OR) and CI were computed for the influential variables included the regression analyses.
We conducted a sensitivity analysis using a model specification which included the dichotomous variables for testing and for treatment, and the interaction term between these variables to assess if treatment effects varied in tested and untested patients. We also estimated this model of revisit risk using revisits within 7 days as the outcome variable.
All analyses were completed using STATA/IC 13 (StataCorp, College Station, TX).