Research Suggests Diagnostic Potential of the API


A new study suggests the Asthma Predictive Index can be used as a simple, noninvasive tool for determining asthma in preschoolers.

Jose A. Castro‐Rodriguez, MD, PhD

A recent birth cohort from Chile suggested that the Asthma Predictive Index (API) could be used as a diagnostic tool in toddlers and preschoolers.

With as many as 70%-80% of children developing asthma symptoms as early as 5 years old, the suggestion proposed by Jose A. Castro‐Rodriguez MD, PhD and colleagues could be crucial in the future of pediatric asthma management.

Asthma rates have risen steadily across the world in recent decades, with overall morbidity such as activity limitation, sleep disturbance, urgent care and emergency department visits, and hospitalizations being much more prevalent in younger patients.

Researchers considered the API to be an important prognostic tool, but the most recent study suggested it could be used as a surrogate for asthma diagnosis in preschoolers based on a longitudinal birth cohort.

The Study

Castro‐Rodriguez and colleagues briefly touched on the birth cohort that was conducted in Santiago, Chile, which culled information from pregnant women and their children through cord blood samples and follow-up visits every 6 months through age 24 months and in-person follow-ups at 30 months.

The cohort included 339 pregnant women and their children who were enrolled in the study between 2014-2016.

Biomarkers and cytokines were measured in the cord plasma of the infants, which included insulin, leptin, interleukins, tumor necrosis factor‐α, adiponectin, ultra‐ sensitive C‐reactive protein (CRP), insulin, lipids, 25‐hydroxyvitamin D (25(OH)D), and Clara or club cell secretory protein (CC16).

At age 30 months, WBC and the following cytokines were measured in a peripheral blood sample: CC16, adiponectin, leptin, CRP, thymic stromal lymphopoietin (TSLP), and serum immunoglobulin E (IgE) mixed antibodies with ImmunoCAP Phadiatop.

Bivariate and multivariable analyses were conducted to evaluate the association between PCP-diagnosed asthma and API status.

Additionally, potential confounders such as maternal BMI, education, oral contraceptive use, birthweight, placenta weight, pets at home at 6 months, age at daycare start, gastroesophageal reflux disease (GERD) by 12 months, acute otitis media (AOM) by 18 months; bronchiolitis, croup, and pneumonia before diagnosis were considered.

The Findings

Castro‐Rodriguez and colleagues found there no significant differences in baseline characteristics between mothers of positive API (API+) and negative API (API–) children.

Additionally, API+ and API– children were similar in terms of most sociodemographic and perinatal characteristics. Despite API+ children having slightly higher birth weight and heavier placenta than API– children, the study showed that the differences did not reach statistical significance.

During the bi‐annual follow‐up surveys, API+ children had a significantly higher prevalence of symptoms associated with asthma than API– children such cough after crying, laughing, agitation, croup, pneumonia, and antibiotics for respiratory infections. Researchers noted that API+ children were younger at the first episode of bronchiolitis compared to API– children.

The API+ group had a higher prevalence of reported physician diagnosis of asthma than the API– group as well as more frequent oral corticosteroid (OCS) courses, inhaled corticosteroid (ICS) use, ED visits for wheezing, and hospitalizations for wheezing.

API+ children also had significantly higher adiponectin in cord blood and higher IL‐10 at 30 months than API– children, but there were no other significant differences in adipokines or cytokines.

The proportion of detectable Phadiatop at 30 months was also similar between API groups.

Overall, API+ children showed 5.7‐fold greater odds of physician‐diagnosed asthma as well as higher odds of OCS and ICS use, ED visits, and hospitalizations for wheezing than those who were API−.

Castro‐Rodriguez and colleagues noted that their findings were similar to a previous cross-sectional study in the United States that lobbied that the API was suitable for ascertaining asthma status.

They believed the recent study proved that the API could act as a simple, noninvasive, and easy‐to‐implement tool for asthma diagnosis in preschoolers with high confidence, though further research was suggested.

“This longitudinal birth cohort study suggests, for first time, that API+ can act as a proxy for the diagnosis of asthma in the first three years of life. Therefore, the API (a structured definition for asthma), could be used as a diagnostic tool (not only as a prognosis tool), but more studies are needed to replicate these findings.

The study, “The asthma predictive index as a surrogate diagnostic tool in preschoolers: Analysis of a longitudinal birth cohort,” was published online in Pediatric Pulmonology.

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