Usefulness of the Nasal Allergen Provocation Test in the Diagnosis of Shellfish Allergy.

BACKGROUND AND OBJECTIVES: Shellfish allergy is a major cause of food allergy and anaphylaxis worldwide. Several allergenic proteins have been described in the last few years, but the only diagnostic tool that still enables discrimination between allergic and nonallergic sensitized persons is the oral food challenge (OFC). The aim of this study was to evaluate the usefulness of the nasal allergen provocation test (NAPT) as a diagnostic tool in shellfish allergy. METHODS: Forty-five patients with confirmed sensitization to shrimp by a positive skin prick test (SPT) result with a commercial shrimp extract were recruited and classified as sensitized-allergic or sensitized-nonallergic based on current tolerance to shrimp intake, the result of an OFC with a freeze-dried cooked shrimp mixture extract, or a recent history of anaphylaxis induced by shrimp ingestion. These patients and 10 controls not sensitized to shrimp underwent NAPT with a freeze-dried cooked shrimp mixture extract. The response was evaluated using acoustic rhinometry and a visual analog scale. RESULTS: Significant differences (P=.001) were found between the sensitized-allergic group (18/20 positive NAPT, 90%) and both the sensitized-nonallergic group (2/18 positive NAPT, 11.1%) and controls (0/10 positive NAPT). NAPT enables differentiation between allergic and nonallergic persons with a sensitivity of 90%, specificity of 89%, positive predictive value of 90%, and negative predictive value of 89%. CONCLUSIONS: Our results indicate that NAPT makes it possible to differentiate between sensitized symptomatic patients and sensitized tolerant patients and could be a valuable diagnostic tool when assessing shrimp allergy.

Risk Factors in Severe Anaphylaxis: Which Matters the Most, Food or Cofactors?

BACKGROUND AND OBJECTIVE: The prevalence of anaphylactic shock, the most severe manifestation of anaphylaxis, remains unknown. Risk factors and biomarkers have not been fully identified. Objective: To identify risk factors in patients who experience anaphylactic shock. METHODS: Using lipid transfer protein (LTP) allergy as a model, we compared the characteristics of patients who developed anaphylaxis and anaphylactic shock. We recorded demographics, pollen sensitization, foods ingested up to 2 hours before onset of the reaction, and the presence of cofactors. Culprit foods were identified through a compatible clinical history and positive allergology work-up (skin prick test and/or sIgE). RESULTS: We evaluated 150 reactions in 55 patients with anaphylaxis (134 reactions) and 12 with anaphylactic shock (16 reactions). Patients in the anaphylaxis group experienced twice as many reactions (mean [SD], 2.4 [2.5] for anaphylaxis vs 1.3 [1.5] for anaphylactic shock; P<.02). No relationship was found between any food group and severity of the reaction. The most frequent food involved in both groups of patients was the combination of several plant-derived foods (plant food mix), followed by peach and nuts. Indeed, in the reactions caused by plant food mix, the presence of a cofactor was observed more often than in other food groups. On the other hand, cofactors were not present in peach- and nut-related reactions. Exercise was the most frequent cofactor in all groups. CONCLUSION: In our series, the severity of the reactions was not determined by the kind of food or presence of a cofactor. Anaphylactic shock seems to be an infrequent presentation that may be associated with other individual-related factors requiring further evaluation.

Usefulness of the Nasal Allergen Provocation Test in the Diagnosis of Shellfish Allergy

Background: Shellfish allergy is a major cause of food allergy and anaphylaxis worldwide. Several allergenic proteins have been described in the last few years, but the only diagnostic tool that still enables discrimination between allergic and nonallergic sensitized persons is the oral food challenge (OFC). Objective: The aim of this study was to evaluate the usefulness of the nasal allergen provocation test (NAPT) as a diagnostic tool in shellfish allergy. Methods: Forty-five patients with confirmed sensitization to shrimp by a positive skin prick test (SPT) result with a commercial shrimp extract were recruited and classified as sensitized-allergic or sensitized-nonallergic based on current tolerance to shrimp intake, the result of an OFC with a freeze-dried cooked shrimp mixture extract, or a recent history of anaphylaxis induced by shrimp ingestion. These patients and 10 controls not sensitized to shrimp underwent NAPT with a freeze-dried cooked shrimp mixture extract. The response was evaluated using acoustic rhinometry and a visual analog scale. Results: Significant differences (P=.001) were found between the sensitized-allergic group (18/20 positive NAPT, 90%) and both the sensitized-nonallergic group (2/18 positive NAPT, 11.1%) and controls (0/10 positive NAPT). NAPT enables differentiation between allergic and nonallergic persons with a sensitivity of 90%, specificity of 89%, positive predictive value of 90%, and negative predictive value of 89%. Conclusions: Our results indicate that NAPT makes it possible to differentiate between sensitized symptomatic patients and sensitized tolerant patients and could be a valuable diagnostic tool when assessing shrimp allergy (AU)

Risk Factors in Severe Anaphylaxis: Which Matters the Most, Food or Cofactors?

Background: The prevalence of anaphylactic shock, the most severe manifestation of anaphylaxis, remains unknown. Risk factors and biomarkers have not been fully identified. Objective: To identify risk factors in patients who experience anaphylactic shock. Methods: Using lipid transfer protein (LTP) allergy as a model, we compared the characteristics of patients who developed anaphylaxis and anaphylactic shock. We recorded demographics, pollen sensitization, foods ingested up to 2 hours before onset of the reaction, and the presence of cofactors. Culprit foods were identified through a compatible clinical history and positive allergology work-up (skin prick test and/or sIgE). Results: We evaluated 150 reactions in 55 patients with anaphylaxis (134 reactions) and 12 with anaphylactic shock (16 reactions). Patients in the anaphylaxis group experienced twice as many reactions (mean [SD], 2.4 [2.5] for anaphylaxis vs 1.3 [1.5] for anaphylactic shock; P<.02). No relationship was found between any food group and severity of the reaction. The most frequent food involved in both groups of patients was the combination of several plant-derived foods (plant food mix), followed by peach and nuts. Indeed, in the reactions caused by plant food mix, the presence of a cofactor was observed more often than in other food groups. On the other hand, cofactors were not present in peach- and nut-related reactions. Exercise was the most frequent cofactor in all groups. Conclusion: In our series, the severity of the reactions was not determined by the kind of food or presence of a cofactor. Anaphylactic shock seems to be an infrequent presentation that may be associated with other individual-related factors requiring further evaluation (AU)

Antecedentes: La prevalencia del shock anafiláctico sigue siendo desconocida. Aún no se han identificado completamente factores de riesgo ni biomarcadores. Objetivo: Identificar factores de riesgo de shock anafiláctico. Método: Utilizando la alergia a proteína de transferencia de lípidos (LTP) como modelo, se han comparado características de pacientes que han presentado una anafilaxia (An) y pacientes que han desarrollado un shock anafiláctico (SAn). Se recopilaron datos demográficos, sensibilización a pólenes, alimentos ingeridos hasta 2 horas antes del inicio de la reacción y la presencia o no de cofactores. El alimento implicado se identificó mediante historia clínica compatible y estudio alergológico positivo (prick test y/o IgE). Resultados: Se evaluaron un total de 150 reacciones; 55 pacientes del grupo An sufrieron 134 reacciones, y 12 pacientes del grupo SAn sufrieron 16 reacciones. El grupo An experimentó el doble de reacciones por paciente (media [DS] 2,4 [2,5] en An vs 1,3 [1,5] en SAn, p<0,02). No se observó relación entre el tipo de alimento y la gravedad de la reacción. El alimento implicado con más frecuencia en ambos grupos fue la combinación de varios vegetales (“mix de vegetales”), seguido por el melocotón y frutos secos. No hubo cofactores implicados en las reacciones con melocotón ni con frutos secos. En ambos grupos el eje rcicio fue el cofactor involucrado con más frecuencia.Conclusión: En nuestra serie, el alimento y la presencia de cofactor no determinan la gravedad de una reacción. Los shocks anafilácticos parecen ser una presentación infrecuente y podrían estar relacionados con factores individuales que precisarán una evaluación más extensa (AU)