Hypersensitivity to Allergens May Increase Risk of Acute Chest Syndrome in Sickle Cell Anemia Children

Hypersensitivity to allergens in children with sickle cell anemia may increase the risk of acute chest syndrome, a study suggests.

The study “Aeroallergen sensitization predicts acute chest syndrome in children with sickle cell anaemia” was published in the British Journal of Haematology.

Diagnosing asthma in children with sickle cell anemia is tricky, but the disease is actually a serious risk factor for increased acute vaso-occlusive pain, acute chest syndrome and earlier death among these patients. Acute chest syndrome is a life-threatening lung-related complication of sickle cell disease characterized by low oxygen levels.

Since increased sensitivity to allergens is a risk factor for asthma, a group of researchers “hypothesized that aeroallergen sensitization is associated with an increased incidence of hospitalizations for ACS [acute chest syndrome] and pain.”

They analyzed data from children aged 4 to 18 years with sickle cell anemia and who participated in the Sleep and Asthma Cohort Study and underwent allergy skin prick testing for 10 aeroallergens: “Aspergillus fumigatus, house dust mite (Dermatophagoides pteronyssinus and Dermatophagoides farinae), cockroach (American and German), cat (standardized), dog (mixed breeds), mouse, Alternaria alternata, grass (standardized southern mix), tree (eastern 8 tree mix) and weed (national mix).”

Out of 252 participants in the Sleep and Asthma Cohort, 188 had clinical data available from birth and 165 had allergy skin test data with a five-year follow up.

Forty-one percent of the participants had at least one positive skin test and 59 percent were negative for reaction to the allergens tested.

The analysis showed that having a positive skin test was predictive of future acute chest syndrome rate, but not acute vaso-occlusive pain.

An “increase of 1 positive test was associated with a 23% increased rate of future ACS [acute chest syndrome] episodes,” researchers wrote.

They noted that the number of positive skin tests was associated with increased rates of acute chest syndrome in children without asthma, but the association was no longer detected if a diagnosis of asthma was confirmed.

Researchers developed the atopy (the tendency to develop hyperallergic recations) index based on four factors: aeroallergen sensitization, levels of the immunoglobulin IgE (an antibody associated with allergic reactions), number of certain white blood cells, and a history of asthma in either parent.

Among 132 participants with data available for all four factors, analysis showed that the atopy index equally predicted future rates of acute chest syndrome, but not acute vaso-occlusive pain.

Overall, “our study demonstrated that children with SCA [sickle cell anaemia] and aeroallergen sensitization are at increased risk for future ACS [acute chest syndrome],” researchers wrote.

“Future research is needed to determine whether identification of specific sensitizations and allergen avoidance and treatment reduce the risk of ACS [acute chest syndrome] for children with SCA [sickle cell anaemia],” the study concluded.