Discussion
Our study suggests that FeNO-SC achieving better outcomes at a lower cost over standard treatment without FeNO in children with mild to moderate allergic asthma. These better outcomes are due to reductions in the probabilities of asthma exacerbation and sub-optimal control of the disease, with the consequent increase of patients well controlled. The magnitude of annual cost savings for the health system (US$ 118 per patient ) is no negligible if we consider that this disease affects between 10 to 13% of children and only 2.4% of them meet the criteria for total asthma control in Colombia. The findings constitute a new argument to include the FeNO-SC in clinical practice guidelines of pediatric asthma.
Our findings are in line with previous studies in the literature evaluating the economic value of FeNO of inserting FeNO monitoring into asthma management, some of them enrolling pediatric patients. Beerthuizen et al. assessed the cost-effectiveness of web-based monthly monitoring and of 4-monthly monitoring of FeNO as compared with standard care. The economic evaluation was performed alongside a multicentre RCT with a 1-year follow-up, and included 272 children aged between 4 and 18 years of age. The FeNO-based strategy had 83% chance of being most cost-effective at \euro40 000/QALY from a societal perspective (18). Berg et al. assessed the cost-effectiveness of FeNO measurement with NIOX MINO in the diagnosis of asthma and in optimizing asthma management using the expected reimbursement price of the device. In this study, the use of FeNO measurement in treatment decisions was less costly than asthma management based on standard guidelines (while in mild to severe patients, asthma management with FeNO measurement instead of standard guidelines resulted in cost-savings of \euro30 per patient and year, in more severe population, management with FeNO measurement would save costs of \euro160 per patient) and provided similar health benefits (7). Brooks et al. examined the impact of FeNO monitoring on the cost-effectiveness of asthma management compared with management without FeNO. FeNO in conjunction with current standard of care guidelines had decreased expected per-patient annual expenditure (US$2,228) and increased expected per-patient annual QALYs (0.844) compared with current standard of care alone (US$2,637 and 0.767)(9). Price et al. determined the cost-effectiveness of FeNO measurement using a hand-held monitor (NIOX MINO), at a reimbursement price of £23, for asthma diagnosis and management in the UK. Asthma management using FeNO measurement instead of lung function testing resulted in annual cost-savings of £341 and 0.06 QALYs gained for patients with mild to severe asthma and cost-savings of £554 and 0.004 QALYs gained for those with moderate to severe asthma(19). Sabatelli et al. evaluated the cost-effectiveness and budget impact of FeNO monitoring for management of adult asthma in Spain over a 1-year period. Adding FeNO to standard asthma care saved \euro62.53 per patient-year and improved QALYs by 0.026 per patient-year. The budget impact analysis revealed a potential net yearly saving of \euro129 million if FeNO monitoring had been used in primary care settings in Spain.8 Similarly, Harnan et al. assessed the cost-effectiveness of the hand-held electrochemical devices NIOX MINO® (Aerocrine, Solna, Sweden), NIOX VERO® (Aerocrine) and NO breath® (Bedfont Scientific, Maidstone, UK) for the diagnosis and management of asthma. The de novo management model indicated that the ICER of guidelines plus FeNO monitoring using NO breath compared with guidelines alone in children is expected to be approximately £45,200 per QALY gained, concluding that FeNO-guided management has the potential to be cost-effective, although this is largely dependent on the duration of effect(10)
The last version of the Global Initiative for Asthma refers to children “ FeNO-guided treatment significantly reduces exacerbation rates compared with guidelines-based treatment (Evidence A). However, further studies are needed to identify the populations most likely to benefit from FeNO-guided treatment, and the optimal frequency of FeNO monitoring”(2). However, in the references that support this statement included only RCTs and not economic evaluations were revised. The dynamics between clinical research in the effectiveness and research of efficiency of the allocation of health resources must be coordinated, synchronous of the moment to make a recommendation from individual to public health level. It is clear the complexity of the transferability of economics evaluations, but this situation highlights the need to assess the health technologies in the clinical guidelines no only evaluating effectiveness or safety but also review economical topics to increase the level of recommendation in clinical guidelines.
A very important aspect of our model is that it was robust to changing the values ​​of the model’s utilities, probabilities, and costs using oneway and probabilistic sensibility analysis of a Markov model. FeNO-SC was always the cost-effectiveness strategy in all ranges of values of utilities, probabilities, and costs. Even more, FeNO-SC was always the cost-effectiveness strategy in all ranges of thresholds evaluated with a low population EVPI. These findings in the sensibility analysis have cardinal importance in our study because many of the inputs were extracted from literature, which all were hospital-based and undertaken in affluent countries; also allow decision making with an estimated degree of uncertainty in each cost parameter or QALYs per strategy.
Our study has some limitations. The cost data were collected retrospectively. Asthma treatment and the costs in question, including hospital prices, did not markedly change to our days. Furthermore, our country has been characterized by having a very small price variation in the last 10 years, especially in health services (14). Additionally, we use utilities extracted from the literature and not estimated directly from our population. As was mentioned previously, the reliability and robustness of the results were evaluated by sensitivity analyses.
In conclusion, the FeNO-SC was cost-effective for infant with asthma moderate or severe. Our study provides evidence that should be used by decision-makers to improve clinical practice guidelines and should be replicated to validate their results in other middle-income countries.