Outcomes or definition of effectiveness
The primary outcome of effectiveness was DALYs averted, and the secondary measure of effectiveness was the number of patients cured. Cure was defined as the disappearance or re-epithelialization of the lesions, complete loss of induration or flattening of the lesion, and disappearance of lymphangitis or adenitis up to 3 months after the end of treatment, without reactivation of the lesion or the appearance of new lesions or mucosal involvement 6 months post treatment [
18].
One DALY corresponds to 1 year of healthy life lost due to ill-health, disability or premature death, measuring the disease burden for specific causes. It provides a general and specific view of the health status of a population, helping to
"make decisions and comparisons, prioritize resources, and implement follow-up in the health system" [
19]. In its calculation, the following components are taken into account: i) life expectancy, which, according to the recommendation of previous studies of disease burden in Colombia, corresponds to 80 years for men and 82.5 for women; ii) the age weight, with which the years of healthy life of the young are valued more by having greater productive capacity; iii) the disability weight, which relates the specific disability of the disease during its course and the time lost by mortality, which is zero for ideal health states and one for states comparable to death; and (iv) the discount rate, which gives greater importance to current benefits, compared to future benefits [
19].
To calculate DALYs, the years of life lost (YLL) due to premature death are combined with the years lived with disability (YLD) due to a disease with a given severity and duration, based on the following statistics quoted from the study by Martínez [
12], which are simultaneously based on WHO reports [
12,
14,
29]:
$$ \mathbf{YLL}=\mathrm{KCerA}/\left(\mathrm{r}+\upbeta \right)2\;\Big\{\mathrm{e}\hbox{-} \left(\mathrm{r}+\upbeta \right)\left(\mathrm{L}+\mathrm{A}\right)\left[\hbox{-} \left(\mathrm{r}+\upbeta \right)\left(\mathrm{L}+\mathrm{A}\right)\hbox{-} 1\right]\hbox{--} \mathrm{e}\hbox{-} \left(\mathrm{r}+\upbeta \right)\mathrm{A}\ \left[\hbox{-} \left(\mathrm{r}+\upbeta \right)\mathrm{A}\hbox{-} 1\left]\Big\}+\right[\left(1\hbox{-} \mathrm{K}\right)/\mathrm{r}\right]\left(1\hbox{-} \mathrm{e}\hbox{-} \mathrm{rL}\right) $$
$$ \mathbf{YLD}=\mathrm{DKCerAs}/\left(\mathrm{r}+\upbeta \right)\ 2\ \Big\{\mathrm{e}\hbox{-} \left(\mathrm{r}+\upbeta \right)\left(\mathrm{Ld}+\mathrm{As}\right)\left[\hbox{-} \left(\mathrm{r}+\upbeta \right)\left(\mathrm{Ld}+\mathrm{As}\right)\hbox{-} 1\right]\hbox{--} \mathrm{e}\hbox{-} \left(\mathrm{r}+\upbeta \right)\mathrm{As}\ \left[\hbox{-} \left(\mathrm{r}+\upbeta \right)\mathrm{As}\hbox{-} 1\left]\Big\}+\right[\left(1\hbox{-} \mathrm{K}\right)/\mathrm{r}\right]\ \left(1\hbox{-} \mathrm{e}\hbox{-} \mathrm{rLd}\right) $$
DALYs were estimated in an Excel spreadsheet from the WHO Global Burden of Disease (2016) study, with the following data taken from the National Public Health Surveillance System (Sistema Nacional de Vigilancia en Salud Pública–SIVIGILA) and studies on disease burden in Colombia in 2005 and 2010 [
1,
8,
19]:
K = 0.5. Age-weighting factor (0 = no age weights; 1 = full age weights).
β = 0.04. Age-weighting parameter.
r = 0.03. Discount rate for the years of life by time preference.
C = 0.1658. Model constant, standard age weighting.
A: Age of the patient who died from leishmaniasis, corresponding to one woman in the age group between 70 and 74 years and four men in the age groups of 0–4, 30–34, 45–49, and over 80 years old.
L: Life expectancy. Men 80; women 82.5 years.
D: Disability weight. According to the WHO recommendation, D is 0.022875 for patients with cutaneous leishmaniasis of all age groups treated and untreated.
As: Age of the patient at the time of the disease, by estimating the percentage distribution by age group and sex of incident cases of cutaneous leishmaniasis in Colombia and the average age of each age group.
Ld: Duration of the event. According to the Colombian disease burden studies, for the age groups of 0–4, 5–14, 15–29, 30–44, 45–59, 60–69, 70–79, and over 80 years of age, the following durations are found: 1.2, 10.4, 23.2, 36.5, 51.1, 64.6, 74.6, and 91.7, respectively [
1,
8,
19].
Time horizon: One year, corresponding to the time window in which incident cases of morbidity and mortality due to this disease were recorded. In addition, it is sufficient time for the evaluation of the outcomes of interest because DALYs take into account morbidity and mortality due to leishmaniasis in 1 year and cure is defined based on a follow-up of 6 months. Given this time horizon, no discount rate was applied.
Resources: A cost per patient expressed in US dollars was determined and validated by five experts (three doctors and two dermatologists who handle this type of patient) in the phases of identification, measurement, and evaluation. In the identification phase, the direct cost-generating events described in the management guides and by the experts were identified, including the costs of applying the intervention (medication, doctor, and nurse), the use of diagnostic aids, and the management of local and systemic side effects. In the measurement phase, the quantity and frequency of use of each identified cost were established. The evaluation phase included data from the standardized tariff manuals for Colombia such as Traffic Accident Mandatory Insurance (SOAT) and the Drug Pricing Information System (SISMED), although it should be noted that the monetary results do not correspond to costs but only to tariffs or rates that have been agreed upon for the provision of health services in Colombia.