Multiple drug intolerance syndrome: prevalence, clinical characteristics, and management

Population-based data on the demographics and clinical characteristics of patients with multiple unrelated drug class intolerances noted in their medical records are lacking.

To provide population-based drug "allergy" incidence rates and prevalence, and to identify individuals with multiple drug intolerance syndrome (MDIS) defined by 3 or more unrelated drug class "allergies," and to provide demographic and clinical information on MDIS cases.

Electronic medical record data from 2,375,424 Kaiser Permanente Southern California health plan members who had a health care visit and at least 11 months of health care coverage during 2009 were reviewed. Population-based drug "allergy" incidence rates and prevalence were determined for 23 unrelated medication classes.

On January 1, 2009, 478,283 (20.1%) health plan members had at least one reported "allergy." Individuals with a history of at least 1 "allergy" and females, in general, reported higher population-based new "allergy" incidence rates. Multiple drug intolerance syndrome was present in 49,582 (2.1%). The MDIS cases were significantly older, 62.4 ± 16.1 years; heavier, body mass index 29.3 ± 7.1; and likely to be female, 84.9%, compared with average health plan members. They had high rates of health care utilization, medication usage, and new drug "allergy" incidence. They sought medical attention for common nonmorbid conditions.

Multiple drug intolerance syndrome is in part iatrogenic. It is associated with overweight elderly women who have high rates of health care and medication usage. Urticarial syndromes only explain a small fraction of MDIS cases. Multiple drug intolerance syndrome is associated with anxiety, but not predominately with immunoglobulin E (IgE)-mediated allergy or life-threatening illness. Multiple drug intolerance syndrome can be managed by medication avoidance and judicious rechallenge.