Elective penicillin skin testing and amoxicillin challenge: Effect on outpatient antibiotic use, cost, and clinical outcomes,☆☆,,★★

https://doi.org/10.1016/S0091-6749(98)70097-1Get rights and content

Abstract

Background: Elective penicillin skin testing in advance of acute antibiotic need and amoxicillin challenge in patients with negative skin test responses have not been evaluated. Methods: I reviewed 236 patients previously entered in a study of new penicillin reagents who received at least 1 prescription drug over a 2-year period. Antibiotic use, outpatient visit rate, and adverse reactions to antibiotics during the year before and after skin testing were evaluated. Results: Forty (17%) of the 236 subjects had positive responses. Antibiotic courses dispensed to the 236 subjects fell 28% from 779 the year before testing to 558 the year after testing. The total cost for antibiotics dispensed fell 32% from $17,211.88 to $11,648.27, with a 5.5% reduction in the average cost per antibiotic. Outpatient visit rate did not change but shifted from primary to specialty departments in subjects with both positive and negative skin test responses. In 93 subjects with negative skin test responses, a total of 188 therapeutic courses of penicillin during the year after testing resulted in 3 (3.2%) unrechallenged mild adverse reactions. Optional amoxicillin challenge in 146 of the subjects with negative skin test responses resulted in complaints of an adverse reaction in 6 of these subjects. Four of these received a penicillin analogue in the next year without reaction. Conclusions: Elective penicillin skin testing done by an allergist was associated with unexpected declines in the number and cost of antibiotics used the year after testing but only modestly lowered the average cost per antibiotic. Adverse reactions to penicillins in subjects with negative skin test responses were infrequent, and amoxicillin challenge did not affect outcomes. (J Allergy Clin Immunol 1998;102:281-5.)

Section snippets

Study design and patient selection

A natural history study on 255 patients who underwent PenSTs between November 16, 1994 and November 15, 1995 was performed. A subgroup of 237 patients (92.9%) who were health plan members during the full year before and after PenSTs and who obtained at least 1 prescription medication from a health plan pharmacy were identified. One outlier with a mycobacterium lung infection, who accounted for 4.2% of all antibiotic courses and 18.4% of antibiotic costs for the 2-year duration of the study, was

Demographics of the study subjects

The demographics of the 236 subjects in this study are displayed in Table I.The clinical histories of the study subjects, including the type of index adverse reaction, time to onset of adverse reaction after initiation of antibiotic therapy, and treatment of the index adverse reaction, are not significantly different from the whole population as reported previously.8

AC

The demographics of the 146 subjects who self selected AC are displayed in Table II and compared with those of subjects who refused AC.

. Amoxicillin challenge

Empty CellAC (n = 146)No AC (n = 50)P value
Age (yrs)37.4 ± 22.447.7 ± 21.0.0072
Female99 (67.8%)34 (68.0%)NS
Time since reaction (yrs)15.58 ± 16.2316.23 ± 16.55NS
Dispensed penicillin (yr before PenST)27 (18.4%)13 (26.0%)NS
Dispensed penicillin (yr after PenST)69 (47.3%)24 (48.0%)NS
Reported adverse reaction with AC or therapeutic course of penicillin (yr

DISCUSSION

Up to 10% of outpatients will report histories of PCA “allergy.”8, 9, 10 The specifics of the clinical history of the adverse reaction have been shown to be inadequate to safely determine true allergy as defined by the presence of specific IgE directed against penicillin determinants.8, 11 Thus physicians must avoid PCAs in any patient claiming penicillin allergy unless the allergy can be disproven. PenSTs have been previously shown to identify those individuals at highest risk for serious

Acknowledgements

I thank Denice D. Wei-Tsao, MS, for statistical assistance and outpatient care data acquisition; Girma Wolde-Tsadik, PhD, for statistical assistance; Randy Nakahiro, PharmD, for pharmacy record acquisition; Robert Zeiger, MD, PhD, for editorial assistance and general support; the Allergy Nurses for performing the PenSTs and ACs; and the Allergy Physicians of the SCPMG for enrolling patients.

References (15)

There are more references available in the full text version of this article.

Cited by (77)

  • Drug Allergy

    2022, Allergy Essentials
  • An educational intervention about the classification of penicillin allergies: effect on the appropriate choice of antibiotic therapy in pregnant women

    2020, International Journal of Obstetric Anesthesia
    Citation Excerpt :

    The proportion of pregnant women in our study who reported penicillin allergy was around 6% during both periods. This proportion is similar to that within the general adult population, which ranges from 5% to 10%.21–23 The prevalence of penicillin allergies reported among pregnant women was recently assessed at 8.4% among 170 000 women in California.4

  • Improving the Effectiveness of Penicillin Allergy De-labeling

    2015, Journal of Allergy and Clinical Immunology: In Practice
View all citing articles on Scopus

From Kaiser Permanente, San Diego Medical Center, Department of Allergy, UCSD School of Medicine, Department of Medicine, San Diego.

☆☆

Supported by Southern California Permanente Medical Group, Kaiser Permanente Southern California.

Reprint requests: Eric Macy, MD, 7060 Clairemont Mesa Blvd, San Diego, CA 92111.

★★

0091-6749/98 $5.00 + 0  1/1/91477

View full text