Patch tests in non-immediate cutaneous adverse drug reactions: Late readings on Day 4 is more sensitive than on Day 3.

BACKGROUND: Patch tests (PTs) are recommended to identify the culprit drug in non-immediate cutaneous adverse drug reactions (NICADRs). We recently reported that, in patients with NICADRs, a unique reading of PTs at day (D)2 compared with an additional second late reading at D4 missed almost half (45.3%) of the positive PTs. OBJECTIVES: To assess the change in sensitivity of the PT reading on D4 compared with the reading on D3. METHODS: We performed a retrospective (July 2020-June 2023) monocentric study of patients who had PTs with two readings for a NICADR. We compared reading on D3 and the second reading on D4 for the suspected drug (primary outcome) and for the related drugs tested simultaneously (secondary outcome). RESULTS: During the study period, 249 patients underwent patch testing with D3 and D4 readings. Regarding the primary outcome, the first reading at D3 was positive for 13.7% of patients, and the reading at D4 for 24.9% of patients (p < 0.0001). Regarding the secondary outcome, only 9.6% of patients had all their positive PT at D3 compared with 24.9% of patients at D4 (p < 0.0001). Considering the evaluated drug classes, no statistical difference was observed. However, we highlight that D3 reading detected all positive carbamazepine PTs (n = 3) while positive clindamycin PTs (n = 4) were identified only with the help of the second reading on D4. CONCLUSION: This study showed that, an additional D4 reading compared with a single D3 reading enhanced the sensitivity of PTs to identify culprit drugs and related. Further studies should replicate these findings and evaluate the medico-economic balance and safety of a single reading of PTs on D4.

Management of Adult Patients With Drug Reaction With Eosinophilia and Systemic Symptoms: A Delphi-Based International Consensus.

Importance: Drug reaction with eosinophilia and systemic symptoms (DRESS) is a rare but potentially fatal drug hypersensitivity reaction. To our knowledge, there is no international consensus on its severity assessment and treatment. Objective: To reach an international, Delphi-based multinational expert consensus on the diagnostic workup, severity assessment, and treatment of patients with DRESS. Design, Setting, and Participants: The Delphi method was used to assess 100 statements related to baseline workup, evaluation of severity, acute phase, and postacute management of DRESS. Fifty-seven international experts in DRESS were invited, and 54 participated in the survey, which took place from July to September 2022. Main Outcomes/Measures: The degree of agreement was calculated with the RAND-UCLA Appropriateness Method. Consensus was defined as a statement with a median appropriateness value of 7 or higher (appropriate) and a disagreement index of lower than 1. Results: In the first Delphi round, consensus was reached on 82 statements. Thirteen statements were revised and assessed in a second round. A consensus was reached for 93 statements overall. The experts agreed on a set of basic diagnostic workup procedures as well as severity- and organ-specific further investigations. They reached a consensus on severity assessment (mild, moderate, and severe) based on the extent of liver, kidney, and blood involvement and the damage of other organs. The panel agreed on the main lines of DRESS management according to these severity grades. General recommendations were generated on the postacute phase follow-up of patients with DRESS and the allergological workup. Conclusions and Relevance: This Delphi exercise represents, to our knowledge, the first international expert consensus on diagnostic workup, severity assessment, and management of DRESS. This should support clinicians in the diagnosis and management of DRESS and constitute the basis for development of future guidelines.

In Situ Patch Test and Repeated Open Application Test for Fixed Drug Eruption: A Multicenter Study.

BACKGROUND: Few studies have evaluated allergy workup in fixed drug eruption (FDE) in a large population. OBJECTIVE: To evaluate the sensitivity of a standardized allergy workup for diagnosing the cause of FDE, with a focus on in situ repeated open application tests (ROATs). METHODS: In a retrospective multicenter study, we analyzed the practice of conducting a complete allergy workup for the etiological diagnosis of FDE. It consisted of 3 steps: in situ patch tests (PTs) for all cases except pure mucosal involvement, followed by in situ ROAT if in situ PT results were negative, and finally a drug challenge (DC). The in situ ROAT involved daily application of the suspected drug on a previously affected FDE site for 7 days. RESULTS: Of 98 suspected FDE cases, 61 patients (median age 61 y; male-to-female ratio 1.8) with a complete allergy workup were included. In 4 cases, even the DC yielded negative results. Among the remaining 57 patients with a positive workup, implicated drugs included paracetamol (12 cases), ß-lactams (11 cases), imidazoles (9 cases, including 5 with metronidazole), nonsteroidal anti-inflammatory drugs (8 cases), iodinated contrast media (4 cases), cotrimoxazole (3 cases), and various other drugs in 10 patients. The diagnosis was confirmed by in situ PT in 17 of 54 cases (31.5%), in situ ROAT in 14 of 40 cases (35%) (with 4 cases showing remote reactivation of FDE sites), and DC in 26 cases. CONCLUSIONS: The sequential allergy workup involving successively in situ PT, in situ ROAT, and DC is a reliable and safe method for diagnosing the cause of FDE. In situ tests exhibited a sensitivity of over 50%.

Allergic contact dermatitis from essential oil in consumer products: Mode of uses and value of patch tests with an essential oil series. Results of a French study of the DAG (Dermato-Allergology group of the French Society of Dermatology).

OBJECTIVE: To analyse the clinical characteristics and sensitivity of an essential oil patch test series (EOS) in patients sensitized to their own essential oils (EOs). METHOD: We analysed the clinical data and patch test results obtained with the European baseline series (BSE) and an EOS, as well as the mode of use of EOs, through a questionnaire included in the patient file. RESULTS: The study included 42 patients (79% women, average age 50 years) with allergic contact dermatitis (ACD), 8 patients required hospitalization. All patients were sensitized to the EO they used, primarily lavender (Lavandula augustifolia, 8000-28-0), tea tree (Melaleuca alternifolia leaf oil, 68647-73-4), ravintsara (Cinnamomum camphora oil, 92201-50-8), and 2 cases were attributed to helichrysum (helichrysum italicum flower absolute, 90045-56-0). 71% had positive patch tests to fragrance mix I or II, 9 only to the EOS and 4 only with their personal EO. Interestingly, 40% of patients did not spontaneously mention the use of EOs, and only 33% received advice on their use at the time of purchase. CONCLUSION: Patch tests with the BSE, limonene and linalool HP, and oxidized tea tree oil is sufficient to detect most EO-sensitized patients. The most important is to test the patient's own used EOs.

Hand eczema in glove-wearing patients.

BACKGROUND: Allergic contact dermatitis to gloves is mostly induced by rubber accelerators. The European baseline series (EBS) appears insufficient to detect glove allergy. Since 2017, it is recommended to use the European rubber series (ERS) and to test the patients' own gloves. OBJECTIVES: To investigate the clinical profile of glove-wearing patients with hand eczema (HE) and to evaluate their sensitisation profile to glove allergens and the value of testing the patients' own gloves. METHODS: We conducted a French multicentre study of patients evaluated for HE between 2018 and 2020 and tested with the EBS, the ERS and their own gloves in patch tests and semi-open (SO) tests. RESULTS: A total of 279 patients were included; 32.6% of patients had positive tests to their own gloves or to glove allergens. Almost 45% of the sensitisations to glove allergens were detected only by the ERS. Among the patients tested both in patch tests and SO tests with their own gloves with positive results, 28% had positive SO tests only. Polyvinylchloride (PVC) gloves were positive in four patients. CONCLUSION: Our series confirms the need to test the ERS. All the patients' gloves must also be tested including PVC gloves. SO tests with gloves are useful as a complement to patch tests.

Skin Testing and Drug Provocation Tests in Epidermal Necrolysis: A French Experience.

BACKGROUND: There are limited data on the use of skin testing, other than patch testing, and challenges in the evaluation of epidermal necrolysis (EN), including Stevens-Johnson syndrome and toxic epidermal necrolysis. OBJECTIVE: To report a French multicenter experience in skin testing and challenges in EN, and investigate the factors associated with tests' positivity. METHODS: All patients who were evaluated by patch tests (PTs), skin prick tests, intradermal tests (IDTs), or drug provocation tests (DPTs) for EN between 2010 and 2020 were retrospectively included through 2 French drug reaction networks. RESULTS: In total, 113 patients were included from 8 centers. Median (interquartile range) time from EN to hypersensitivity workup was 7.9 months (5.1-15 months). All patients had PTs, 17 (15%) had skin prick tests or IDTs with delayed readings and 32 (28.3%) had DPTs. One mild reaction occurred after a DPT. Overall, 22 patients (19.5%) had positive PTs, and the only factors associated with positivity were Algorithm of Drug Causality for Epidermal Necrolysis (ALDEN) score and drug class. Only 1 IDT was positive but considered irrelevant. The DPTs were never performed to prove responsibility of a highly suspected drug but were used to confirm current tolerance of needed medications. CONCLUSIONS: Allergological workup in EN, performed by specialists involved in EN, seems safe. Skin tests, although of limited sensitivity, can be helpful for considering the reintroduction of essential drugs according to a benefit-to-risk decision. We propose an algorithm for approaching hypersensitivity testing in patients with EN, to be adapted to each patient.

What is the optimal duration for a ROAT? The experience of the French Dermatology and Allergology group (DAG).

BACKGROUND AND OBJECTIVES: The repeated open application test (ROAT) is an adjuvant investigation measure to patch testing in the diagnosis of allergic contact dermatitis. ESCD recommends a 15 days duration but its overall duration varies according to publications and patients hardly adhere to prolonged ROAT duration beyond 1 week. MATERIALS AND METHODS: The Dermatology and Allergy Group of the French Society of Dermatology performed a prospective study with the aim of determining the best duration for the ROAT. RESULTS: A total of 328 ROAT results were collected for topical products, including cosmetics (60%) and topical medications (31.1%). Fifty-nine (18%) ROATs were positive, and 16 (5%) were doubtful. All the positive ROATs occurred within 10 days, with a median time to positivity of 3 days. CONCLUSION: According to our results, a minimum duration of 10 days is necessary to achieve a positive ROAT to a topical product.

Multiple cases of sensitization to an antiseptic containing chlorhexidine digluconate/benzalkonium chloride/benzyl alcohol with different profiles of sensitization in adults and children.

BACKGROUND: An aqueous antiseptic containing "chlorhexidine digluconate/benzalkonium chloride/benzyl alcohol" (CBB) is widely used in France. The only previous documented study dealing with allergic contact dermatitis (ACD) to this antiseptic is one small case series in children. The French Vigilance Network for Dermatology and Allergy (REVIDAL-GERDA) has collected many cases in the last few years. OBJECTIVES: To evaluate the clinical and sensitization profiles of patients diagnosed with ACD to CBB. METHODS: We performed a retrospective study of patients with contact dermatitis to CBB and positive tests to CBB and/or at least one of its components. All patients had to be tested with all components of CBB. RESULTS: A total of 102 patients (71 adults and 31 children) were included. The lesions were extensive in 63% of patients and 55% had delayed time to diagnosis. CBB patch tests were positive in 93.8% of cases. The allergen was identified in 97% of patients, mainly benzyl alcohol in adults (81.7%) and chlorhexidine digluconate in children (54.8%). About 32.4% of the patients were sensitized to several components. CONCLUSION: CBB is a cause of ACD at all ages. The components of the antiseptic should be tested. The sensitization profile seems to be different between adults and children.

Patch tests in nonimmediate cutaneous adverse drug reactions: The importance of late readings on day 4.

BACKGROUND: Patch tests (PTs) with two readings have been used for decades to identify the culprit drug in nonimmediate cutaneous adverse drug reactions (NICADRs), followed more recently by late reading of intradermal tests (IDTs). Some teams tend to perform PTs with only one reading before IDTs or even directly perform IDTs. OBJECTIVES: To evaluate the relevance of a late PT reading on day 4 (D4) in NICADRs. METHODS: We retrospectively selected patients who had a PT for an NICADR between July 2014 and March 2020. RESULTS: During the study period, 328 patients had a PT with available results. Among the 75 positive-PT patients with available data for the two readings, 41 (54.7%) had positive results on D2 and D4 and 34 (45.3%) had negative results on D2 but positive results on D4. No patient had positive results on D2 and negative results on D4. CONCLUSION: This study shows that a D4 reading enhanced the PT-positive results. A positive PT result allows for reducing the number of IDTs, which are more difficult and costly to perform. Our series suggests that a late PT reading at D4 should be performed for exploring NICADRs.