3. Materials and methods

not only Brazil has the largest population in the region (Southern Cone and Andean territory), but also the other countries in this territory are sub-tropical (Paraguay) and non-tropical (Chile, Argentina and Uruguay). The advantage of reviewing the Brazilian case is the large evidence of total and per patient economics costs which has been estimated using micro-costing, bottom-

Finally, for the Caribbean territory, we found that, based on the information from PAHO, between 2014 and 2017, the country with the highest number of dengue cases (31,326) and deaths (209) is the Dominican Republic (Figure 5). In contrast to Brazil, Colombia and Mexico, no published study, which quantifies the cost of the disease per patient considering the same cost structure framework commonly found in the literature (direct and indirect costs), was

up approach from administrative records, household survey and interviews [19].

Figure 5. Dengue cases and mortality in the Caribbean territory (2014–2017). Source: PAHO. 2017.

Figure 4. Dengue cases and mortality in Southern Cone territory (2014–2017). Source: PAHO. 2017.

26 Dengue Fever - a Resilient Threat in the Face of Innovation

To assess the economic cost of the disease, we used the results found for Brazil, Colombia, the Dominican Republic, and Mexico. To maintain cost structure homogeneity, we exploited the common methodological framework used in the literature, which is employed in the papers reviewed. There are three main cost categories used to quantify the economic burden of a disease: direct medical cost, direct non-medical cost, and indirect cost.

Direct medical cost comprises the cost borne by the healthcare unit (professional services, medical inputs, medical drugs, laboratory test). Additionally, direct non-medical cost corresponds to the value expended during a dengue episode and comprises food, lodging and travel expenses. Finally, indirect cost includes the productivity loss5 (by patient and caregivers).

Even though the authors researched a common topic, there are some methodological differences that are worth noting to make a correct comparison between the results. In contrast to Mexico [17], Colombia [18] and Brazil [19] estimate the direct cost per patient grouping the medical and non-medical component in the same category, thus their figures could only be compared to the sum of medical and non-medical direct cost6 from Mexico and Colombia.

Although the three studies present their results in dollars, nominal adjustment<sup>7</sup> was needed<sup>8</sup> , for this we use the GDP deflator calculated by the World Bank for each country. Once the appropriate per patient is defined, the total number of reported dengue cases is required to estimate the total cost in each country; for this, we took the information reported by PAHO for

$$\begin{aligned} \text{GDP}\_{\text{avrain},i} &= \left(1 + \Delta \%\_{\text{real}}^{i,j}\right) \times \left(1 + \Delta \%\_{\text{nominal}}^{i,j}\right) \times \text{GDP}\_{\text{nominal},j} \\\\ \text{GDP}\_{\text{real},i} &= \left(1 + \Delta \%\_{\text{real}}^{i,j}\right) \times \text{GDP}\_{\text{real},j} \\\\ \implies \frac{\text{GDP}\_{\text{nominal},i}}{\text{GDP}\_{\text{real},i}} &= \left(1 + \Delta \%\_{\text{initial}}^{i,j}\right) \times \frac{\text{GDP}\_{\text{nominal},j}}{\text{GDP}\_{\text{real},j}} \\\\ \implies \Delta \%\_{\text{avain},i}^{i,j} &= \frac{\text{def}\_{i}}{\text{def}\_{j}} - 1 \\\\ \text{def}\_{i} &= \frac{\text{GDP}\_{\text{avrain},i}}{\text{GDP}\_{\text{real},i}} \end{aligned}$$

<sup>4</sup> More details about the methodology employed by the authors can be found in [20].

<sup>5</sup> Productivity loss corresponds to a monetary estimate of the days of work lost by the patient as well as caregivers.

<sup>6</sup> Direct non-medical costs include out-of-pocket expenses borne by the patient.

<sup>7</sup> Nominal adjustment accounts for price changes due to inflation between years. This adjustment allows for proper comparison between figures from different years.

<sup>8</sup> To nominally adjust the cost figures the GDP deflator was used for two different years ð Þ i; j .

the year 20159 . Considering potential lack of homogeneity among countries regarding laboratory confirmation practices and policies, we used total reported cases instead of laboratory confirmed cases for our analysis; we allow for this since reported dengue cases also received treatment and PAHO definition for reported cases only includes people "who has a fever or history of fever for 2-7 days duration, two or more symptoms of dengue and one serological test positive or epidemiological nexus with confirmed dengue case 14 days before onset of symptom." Even though using reported dengue cases, we are allowing for a potential overestimation of the economic burden, it is worth noting that by using DALY figures from WHO, we avoid this potential bias in the burden of the disease. It might also be noted that by using this approach, the results we found could be interpreted as an upper bound for the economic burden of the disease. To calculate the total treatment cost, we make the following assumption, and severe cases are considered to receive hospitalized treatment while nonsevere dengue cases<sup>10</sup> are considered to receive ambulatory treatment. From now on, we will refer only to ambulatory cases and hospitalized cases.

Total treatment cost was calculated for both ambulatory and hospitalized cases as presented in Eq. (1).

$$TC = AD \times PPC\_{ambulator} + HD \times PPC\_{hspitalized} \tag{1}$$

where TC represents total cost, AD number of ambulatory dengue cases, HD number of hospitalized dengue cases, and PPC per patient cost.

$$PPC\_i = DMC\_i + DnMC\_i + IC\_{i\prime}$$

$$i \in \{ambulatory, hospitalized\} \tag{2}$$

2015; we preferred DALYs as measurement of the disease's burden because it allows to express

The Burden of Dengue Illness and Its Economics Costs in the Americas: A Review on the Most Affected Countries

Additionally, to estimate the number of DALYs for 2017, which is presented in the discussion section, we used the following approach. Using the DALY estimates of WHO for 2015 and the number of cases of dengue reported by PAHO, we calculated the ratio of DALY per reported

rDALY <sup>¼</sup> # DALY<sup>2015</sup>�WHO

This approach relies on one underlying assumptions, mortality rates do not change dramatically from 2015 to 201712. It is noteworthy that following this approach, we benefit from the WHO information about DALY estimation parameters, reduce bias (noise) from lack of specific data needed to estimate the burden of the disease<sup>13</sup> and get highly comparable estima-

After nominally adjusting the figures, the cost per patient found by the authors for Brazil, Colombia, the Dominican Republic, and Mexico are shown in Table 1. Since the authors used the same cost structure in their estimation process, we can separate the total cost into their main categories (direct medical and non-medical cost and indirect cost). The figures are presented in 2017 prices, which allows for comparison. Table 1 shows the total cost per patient

In the four countries reviewed, Mexico is the one with the most expensive treatment cost per patient in ambulatory care, even when their indirect cost is the lowest. For ambulatory cases, in contrast to Brazil, Colombia, and the Dominican Republic, the direct medical cost in Mexico is larger than the direct non-medical cost and the indirect cost (even when combined). For hospitalized cases, Mexico keeps having the most expensive treatment cost per patient, with

The latter shows that Mexico has the most expensive dengue treatment per patient, regardless of the type of care (ambulatory US\$ 501 or hospitalized US\$ 1,475). On the other hand, the less expensive treatment for ambulatory (US\$ 189) and hospitalized (US\$ 488) cases would be

13Recalling the method used to estimate the total cost of the disease it is noteworthy that the latent risk of overestimation is not present in the estimation of the burden of the disease (DALY), as it is estimated by extrapolating the results of 2005

direct costs that more than double the direct costs of the other countries.

#Cases<sup>2015</sup>�PAHO

DALY<sup>2017</sup> ¼ rDALY � #Cases<sup>2017</sup>�PAHO (4)

http://dx.doi.org/10.5772/intechopen.79887

(3)

29

numerically the burden of the disease as years based on a set of standard weights [21].

dengue case, which we then used to calculate the burden of the disease for 2017.

tions from a homogeneous methodology.

12We do not find this assumption to be particularly strong.

using the ratio of DALY per reported dengue case.

4. Results

disaggregated.

in Brazil.

where DMC represents direct medical cost, DnMC direct non-medical cost and IMC indirect cost. In other words, the total cost of the disease is equal to the number of dengue cases times the cost per patient, for both ambulatory and hospitalized cases. The total treatment cost per patient corresponds to the sum of direct medical cost per patient, direct non-medical cost per patient and indirect cost per patient.

As estimates for the burden of the disease, measured as the number of Disability Adjusted Life Years (DALY)11, we use the figures from the World Health Organization (WHO) for the year

<sup>9</sup> We considered the last published report that includes the information from the whole year. PAHO gathers epidemiological information from official reports made by the countries themselves. Thus, PAHO figures represent the official number of reported dengue cases, death and incidence. This mechanism has been working since 1980 and nowadays counts with systems of mandatory notification across the national territories.

<sup>10</sup>The number of ambulatory dengue cases is equal to the total number of reported cases minus the total number of hospitalized cases; both figures are used as reported by PAHO.

<sup>11</sup>According to WHO, one Disability Adjusted Life Years can be thought of as one lost year of "healthy" life. The sum of these DALYs across the population can be thought of as a measurement of the gap between current health status and an ideal health situation where the entire population lives to an advanced age, free of disease and disability and are calculated as the sum of the Years of Life Lost (YLL) due to premature mortality in the population and the Years Lost due to Disability (YLD) for people living with the health condition or its consequence.

2015; we preferred DALYs as measurement of the disease's burden because it allows to express numerically the burden of the disease as years based on a set of standard weights [21].

Additionally, to estimate the number of DALYs for 2017, which is presented in the discussion section, we used the following approach. Using the DALY estimates of WHO for 2015 and the number of cases of dengue reported by PAHO, we calculated the ratio of DALY per reported dengue case, which we then used to calculate the burden of the disease for 2017.

$$rDALY = \# \frac{DALY\_{2015-WHO}}{\# \text{Cases}\_{2015-PAHO}} \tag{3}$$

$$
\mathbb{T}DALY\_{2017} = rDALY \times \#\text{Cases}\_{2017-PAHO} \tag{4}
$$

This approach relies on one underlying assumptions, mortality rates do not change dramatically from 2015 to 201712. It is noteworthy that following this approach, we benefit from the WHO information about DALY estimation parameters, reduce bias (noise) from lack of specific data needed to estimate the burden of the disease<sup>13</sup> and get highly comparable estimations from a homogeneous methodology.
