The Effect of Penicillin Allergy Testing on Future Health Care Utilization: A Matched Cohort Study.

BACKGROUND: The effect that penicillin allergy testing has on future health care utilization is uncertain.

OBJECTIVE: Determine whether penicillin allergy testing affects future overall health care utilization as measured by outpatient department (OPD) visits, emergency department (ED) visits, and hospital days.

METHODS: Potential cases and control subjects were penicillin allergic Kaiser Permanente Southern California members who had at least 2 visits between 2010 and 2012 and at least 1 year of continuous health plan coverage before their index visit.

RESULTS: It was possible to match 308 (73.2%) of the potential cases to 1251 unique controls, on the basis of age, sex, weighted Charlson comorbidity index, drug class allergies, OPD visits, ED visits, and hospital days during the years before their index visit. Cases and controls were then followed for an average of 3.6 and 4.0 years, respectively. Based on results analyzed using a generalized linear mixed model, cases were estimated to have 0.09 fewer OPD visits (P < .001), 0.13 fewer ED visits (P = .29), and 0.55 fewer hospital days (P < .001) per health plan coverage year during follow-up compared with controls. Cases were exposed to more penicillins and first- and second-generation cephalosporins and less clindamycin and macrolides.

CONCLUSIONS: Penicillin allergy testing, primarily done in the setting of an outpatient Allergy consultation, was associated with significantly less health care utilization during 3.6+ years of follow-up and greater use of narrow-spectrum antibiotics. Penicillin allergy testing has a favorable cost-benefit ratio for the incremental cost of testing versus future health care utilization and improves antibiotic stewardship.