Economic model

The Italian decision model depicting the management of cow’s milk allergic infants was adapted to reflect the structure of the Polish health care system and the context in which CMA is managed in this country. Similarly, patients’ pathways and resource use were adapted using estimates derived from a sample of Polish pediatricians with experience of managing CMA. The period of the model was up to 18 months or when an infant developed tolerance to cow’s milk, if that occurred earlier.

The model was populated with data from an observational study (as previously described).10,11 The percentages of infants who developed oral tolerance to cow’s milk after being fed a formula were used to populate the model with the probability of infants developing tolerance to cow’s milk at different time points, as previously described for our Italian model.11

The model was populated with estimates of health care resource use pertaining to the management of infants with CMA in Poland, which were derived from interviews with a sample of pediatricians.

Twenty-three pediatricians were asked to participate in the study, of whom 15 agreed and eight declined. The sample comprised six general pediatricians, four pediatric gastroen-terologists, and five pediatric allergists. The clinicians were asked about their management of CMA using a structured questionnaire.

The general pediatricians who participated in this study each saw a mean of <10 infants with suspected CMA per month, with a mean age at presentation of ~4 months (range: 3–6 months). According to these pediatricians, 25% would have IgE-mediated allergy and the other 75% would be non-IgE allergic. Twenty percent of all these infants would be referred to a pediatric gastroenterologist and 25% to a pediatric allergist for further investigations and confirmation of diagnosis. The pediatric specialists who participated in this study each saw a mean of 15–20 infants with CMA per month, with a mean age at presentation of ~5 months (range: 2–9 months). Half of the infants referred to a pedi-atric allergist would have IgE-mediated allergy, and 80% of infants referred to a pediatric gastroenterologist would have non-IgE-mediated allergy. More than 90% of infants would be prescribed a formula at the initial visit to a pediatrician and the remainder at the second visit. In addition, 70% of infants would be prescribed an emollient for 6–12 months, 20% an antihistamine for 6 weeks, 10% a proton pump inhibitor for 2 months, and 2% a corticosteroid for 7–10 days.

Pediatricians prescribe formula based on an infants’ age and weight. Hence, up to 3 months of age, it would be ~150 mL/kg/day (500–1,000 mL/day), decreasing to ~120 mL/kg/day (800–900 mL/day) at 6 months of age. Between 7 and 9 months of age, infants would receive ~600 mL/day, decreasing tô400 mL/day at >1 year of age. Infants enter the model at a mean age of <6 months. Hence, it was estimated that infants would be prescribed: 48×400 g cans of formula in the first 6 months of the model, 36×400 g cans of formula in the next 6 months of the model, and 36×400 g cans of formula after twelve months.

Using analysis of covariance (ANCOVA), differences in tolerance acquisition between formulas were adjusted for any differences in the following baseline variables: age, sex, presenting symptoms, and baseline values of the diagnostic tests. Covariates that had a P-value ≥0.05 were excluded from the ANCOVA model. The only covariates that remained were prick test result at baseline (P=0.006), respiratory symptoms at baseline (P=0.03), and atopy test results at baseline (P=0.01). All statistical analyses were performed using IBM SPSS Statistics (v21.0; IBM Corporation, Armonk, NY, USA).

The primary measure of clinical effectiveness was the probability of infants developing tolerance to cow’s milk by 18 months.

Unit costs in Polish Zloty (PLN) at 2013–2014 prices (Table 1)13–15 were assigned to the estimates of resource use in the model. The cost of seeing a general pediatrician was excluded from the analysis, as these clinicians are paid on a capitation basis based on the number of children in their catchment population, irrespective of the number of times they see a child.16 In Poland, parents of affected infants pay a proportion of the cost of prescriptions of nutritional formulas, as shown in Table 1. Additionally, parents pay a proportion of the cost of prescribed drugs and tests if performed by a general pediatrician (Table 1). Hence, the model was used to estimate the cost of health care resource use funded by the NFZ and the cost incurred by parents over 18 months from the start of a formula.

Unit costs 2013–2014 prices (PLN)

Abbreviations: AAF, amino acid formula; eHCF, extensively hydrolyzed casein formula; LGG, Lactobacillus rhamnosus GG; NFZ, Narodowy Fundusz Zdrowia; PLN, Polish Zloty; RAST, radioallergosorbent test.

The model was used to estimate the cost-effectiveness of using one formula compared with another in terms of the incremental cost per additional infant who developed tolerance to cow’s milk by 18 months in Poland. This was calculated as the difference between the expected costs of two dietetic strategies divided by the difference between the expected outcomes of the two strategies in terms of the probability of developing tolerance to cow’s milk. If one of the formulas improved the probability of developing tolerance to cow’s milk for less cost, it was considered to be the dominant (cost-effective) dietetic strategy.