Intradermal testing of iodinated contrast media: Should we test up to pure or with diluted compounds only?
Adrian A Schmid1, Martin N Hungerbühler2, Paolo Lombardo3
1Department of Radiology, Kantonsspital Münsterlingen, Münsterlingen, Switzerland.
Insights
Intradermal testing (IDT) with pure iodinated contrast media (ICMs) is more effective for diagnosing ICM hypersensitivity than diluted versions. Pure ICM IDT shows higher sensitivity and may reduce the need for drug provocation tests (DPTs).
Area of Science:
- Allergy and Immunology
- Radiology
- Pharmacology
Background:
- Intradermal testing (IDT) is used for diagnosing hypersensitivity to iodinated contrast media (ICMs).
- Optimal ICM concentration for IDT (pure vs. diluted) remains unclear.
Purpose of the Study:
- To compare the diagnostic utility of pure versus diluted ICMs in intradermal testing for ICM hypersensitivity.
- To evaluate sensitivity, specificity, and the need for subsequent drug provocation tests (DPTs).
Main Methods:
- Systematic literature search of PubMed for studies on ICM allergy and IDT.
- Meta-analysis of data from 1137 patients comparing diluted and undiluted ICM IDT results.
Main Results:
- Pure ICM IDT showed a significantly higher positive test rate (24.7% vs. 9.0%) and culprit ICM identification rate (72.5% vs. 31.0%).
- Sensitivity was substantially higher with pure ICMs (0.774 vs. 0.282), while specificity remained comparable (1 vs. 0.983).
- Fewer drug provocation tests (DPTs) were needed in the pure ICM IDT group.
Conclusions:
- Intradermal testing with pure ICM concentrations is superior to using diluted ICMs for diagnosing ICM hypersensitivity.
- Pure ICM IDT offers increased sensitivity and potentially reduces the necessity for DPTs.
- No skin irritations or unspecific reactions were observed with pure ICMs during IDT.
Background:
Intradermal testing (IDT) with iodinated contrast media (ICMs) is an established diagnostic tool in patients with ICM hypersensitivity. Currently, it is unclear which test concentration is the more useful one, up to pure or up to 1:10 diluted ICMs.
Methods:
We searched the literature database PubMed for eligible papers dealing with ICM allergy and their IDT results. We analyzed the data presented by the papers and compared the pooled groups tested with diluted and undiluted ICMs.
Results:
We identified 29 eligible original papers, and extracted data of 1137 patients that formed the study population. Although in the cohort tested with diluted ICMs the number of tested ICMs was greater, the percentage of positive tests was significantly less (9.0% vs. 24.7%; P < 0.0001; OR 0.30 [0.26-0.34]). The frequency of positive tested culprit ICMs was also lesser in the group tested with diluted ICMs (31.0% vs. 72.5%; P < 0.0001; OR 0.17 [0.12-0.23]). The number of drug provocation tests (DPTs) was greater in patients with diluted IDTs (374 vs. 89; P < 0.0001; OR 2.54 [1.93-3.36]). We detected an increased sensitivity in patients with undiluted tests (0.774 vs. 0.282) and a nearly identical specificity in both groups (1 vs. 0.983).
Conclusions:
For the first time, we show that IDT up to pure ICM concentrations is superior to using diluted ICMs only. Possibly, we can reduce the number of DPTs when performing IDTs with pure ICMs. In the undiluted group, there were no hints for skin irritations or unspecific test reactions.
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