In children with persistent asthma, researchers in Colombia found that eosinophil count in induced sputum (EO) was a more cost-effective biomarker than fractional exhaled nitric oxide (FENO) for guiding care management — a finding that may have potential for informing practice guidelines for low-resource settings. These were among study findings recently published in BMC Pulmonary Medicine.

Clinical practice guidelines for asthma recommend periodic assessment of airway inflammation as a principal strategy for preventing hospitalization. Both FENO and EO may be used as biomarkers for the purposes of this assessment.

The researchers sought to compare the costs and benefits associated with use of the 2 biomarkers — EO and FENO — for guiding care management in children with asthma between 4 and 18 years of age. The investigators recognized that because some doubt existed about the relative merits of these 2 biomarkers, generating data to clarify this uncertainty might facilitate the development of appropriate and cost-effective clinical practice guidelines. The researchers also incorporated the results of a previous study they had conducted — showing that EO-guided care was more effective than standard asthma management (ie, use of low-dose inhaled corticosteroids [ICS]) — into their final study results.

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A Markov simulation model was used to estimate the costs and quality-adjusted life years (QALYs) associated with care management guided by FENO vs EO. The interventions assessed in this simulation included adjustment of asthma treatment (ie, stepping up or stepping down ICS) based on FENO or sputum eosinophils to adjusting therapy in children aged 4 to 18 years. Health care costs were calculated based on a study of 512 children in Colombia that was previously conducted by study investigators. The estimated costs associated with each health state considered in the model were derived from medical invoices and electronic medical records for these children.

Results of the study showed that the expected annual cost per patient with EO-guided management was US $1376 (95% CI, US $1376 to US $1377), compared with US $1934 (95% CI, US $1333 to US $1334) with FENO-guided management — with a difference of US $42.30 between the 2 management strategies.

Further, the QALYs per person estimated with EO-guided management was 0.95 (95% CI, 0.951-0.952), compared with 0.94 (95% CI, 0.930-0.940) with FENO-guided management — with a difference of 0.01 between the 2 management strategies.

The net monetary benefit (NMB) was estimated as well. “NMB represents the value of an intervention in monetary terms.” With EO, the NMB was US $4902 (95% CI, US $4900 to US $4904), and with FENO, the NMB was US $4841 (95% CI, US $4839 to US $4843).

Among the limitations of the current study is the fact that the data were collected in a retrospective manner. Additionally, Colombia has been characterized as having very low price variation in the last 10 years — particularly with regard to health care services.

The researchers concluded that the evidence presented in this analysis can be used by decision-makers to improve clinical practice guidelines in low-resource settings, although it warrants replication in other clinical settings.


Buendía JA, Guerrero Patiño D, Sánchez Caraballo JM. Fractional exhaled nitric oxide and eosinophil count in induced sputum to guide the management of children with asthma: a cost-utility analysis. BMC Pulm Med. 2022;22(1):257. doi:10.1186/s12890-022-02027-6