CHD: Congenital Heart Disease; CCHD: Critical Congenital Heart Disease; COI: Cost of illness; FCI-IC: Fundación Cardioinfantil – Institute of Cardiology; SMMLV: Monthly Minimum Legal Wage

The term critical congenital heart disease (CCHD) refers to a group of structural malformations of the heart which are present from the prenatal period. They represent more than one third of all Congenital Heart Diseases (CHD) ^{1, 2} . Their incidence ranges from 1 in 15,000 to 1 in 26,000 live births and their prevalence corresponds to 147.4 cases per 100,000 live births ³ . CCHDs are an important cause of child mortality in the first month of life, and consequently it is necessary to start early surgical or interventional treatment in the first year of life to grant the patient’s survival ^{2, 4} . 29.5% of newborns with CCHD are diagnosed late ⁵ , a fact associated with greater risk of morbidity and mortality ⁶ . The CCHD have a significant economic impact on the health systems and the patients’ families; thereby, no studies on indirect costs are available, and few of them address direct medical costs at world level ⁷ .

The purpose of carrying out a costs study on a disease (COI “Cost of Illness”), is to perform a descriptive analysis to identify and measure the costs of a disease in monetary terms to estimate its economic burden on society ^{8, 9} . COI studies may take different perspective that determines the whole costs process; they estimate costs from the standpoint of society, the health system, the patient or the families. The perspective of society is the most comprehensive one and most widely recommended, since it includes all costs, independently from who incurs them. In consequence, besides direct medical costs, out-of-pocket expenses covered by the family, and indirect costs, are included. This society perspective allows to carry out a more complete analysis and include all costs of opportunity attributed to a disease. However, this perspective requires a larger collection and availability of information effort, a fact that hinders its use in COI for low prevalence diseases ^{10, 11} .

Overall, COI studies contemplate three cost categories: direct, indirect and intangible costs, the latter are rarely quantified, so it is accepted that only direct and indirect costs are considered. Direct medical costs are costs related with medical assistance, treatment, rehabilitation, etc.; non direct medical costs involve expenses in non-medical resources, i.e., transportation and nutrition outside the home. Lastly, indirect costs refers to the loss of productivity associated with the disease ¹¹ .

The micro-costing, and gross-costing approaches are used to estimate direct medical costs. The micro-costing is a “bottom-up” process whereby every resource is identified; measuring, assessment and calculation of the total cost are carried out; contrarily, the gross-costing estimates costs from a “top-down” approach, drawing an average of the total cost. The human capital approach and the friction cost approach estimate indirect costs. The loss of productivity is associated with the friction period, i.e., the time the patient takes to be replaced by another employee and for production to return to its former level ¹² .

From the economic standpoint, the needs of the population are endless but the resources to meet them are limited. Additionally, factors like technological development, cause health expenses to increase. The estimation of costs is important in making decisions, as it helps to define and prioritize policies and intervention related with health assistance ¹¹ . Also, it provides information to make future costs projections in medical assistance and allocate resources according to budget limitations, thus granting the efficiency of policies ^{8, 11} .

In view of the importance of CCHD, the complexity presented in terms of costs for society and the scarce literature available on the subject, it was necessary for this study to estimate costs and hence approach the economic burden from a social perspective in Colombia. For this study we benefit from the information provided by Fundación Cardioinfantil – Institute of Cardiology (FCI-IC) and its social program ^{13, 14} , to access a population that is difficult to study. Although many of the expenses incurred by the patients and their families are subsidized by FCI-IC’s social program, the use of resources is real, which allowed to approximate to the real cost incurred by these CCHD patients in Colombia.

The method used to estimate the costs was micro-costing, as the information collected allowed to reach a level of detail in the identification and measuring of resources, and to carry out the assessment based on the national reference prices, and not only on those of a particular institution. Besides, this method identifies gaps in expenses and include only events related with CCHD. The calculations were made in Microsoft Excel 2016. We did not perform any statistical tests.

The seven CCHDs included in the estimation of costs were: Pulmonary Atresia, Tetralogy of Fallot, Tricuspid Atresia, Truncus Arteriosus, Hypoplastic Left Heart Syndrome, Total Anomalous Pulmonary Venous Drainage and Transposition of Great Arteries. The decision to include these CCHDs was made following the approaches and recommendations taken on the subject at world level, thus the prioritization of these cardiopathies in the United States was taken as reference ¹⁵ .

The cost estimation process followed four stages ¹⁰ : 1. Identification of resources; 2. Measuring the use of resources; 3. Assessment of resources; 4. Calculating total costs. This methodology was followed, and the “bottom- up” process, i.e., the estimation of direct medical hospital costs followed an identification of resources, measuring (frequency and quantity) and assessment of resources (as per Tariffs Manual ISS 2001+35%, market prices in Colombia) ¹⁶ , and lastly, the total costs calculation, based on clinical records for 73 patients with the seven CCHDs from the data base of the Institute of Congenital Heart Disease at FCI-IC. Direct annual medical costs were estimated for every CCHD, and for indirect costs and out-of-pocket expenses, 20 surveys were applied to caregivers of children with three Infrequent Congenital Heart Diseases since there is a higher level of complexity in the collection of information on CCHDs. The caregivers were a convenience sample identified from a cohort of the PINOCCHIO Program (Innovation Program in Uncommon Human Congenital Heart Diseases for Colombia). This cohort was built through three main sources at Fundacion Cardionfantil – Instituto de Cardiologia – FCI–IC: medical databases of patients from the Congenital Heart Disease Institute; Pediatric Cardiovascular surgery service; and patients diagnosed during pediatric brigades carried out by FCI-IC social program “Give a life” in 12 cities in Colombia from the period 2010 to October, 2018. The eligibility criteria for the 20 caregivers of children were patients from the PINOCCHIO Cohort with detectable critical congenital heart diseases with the following diagnosis: Ebstein’s anomaly, Interrupted Aortic Arch and Pulmonary Valve Stenosis and which were less than two years of age at the time of the survey. The caregivers filled a case report form (CRF) whereby information on out-of-pocket expenses and indirect costs was obtained. Before caregivers started to answer the survey, a research assistant explained the objective, asked for signed informed consent, and were present to respond to any question. A copy of the CRF translated to English is attached as extended data.

The perspective taken in cost estimation was that of society. All costs are expressed in US dollars, firstly estimated in Colombian pesos for 2017, and then the average exchange rate for 2017 was applied ($2,951.15 COP for one US dollar) ¹⁷ .

The results of this study are consistent with a high economic impact of CCHDs on the health system and on families in Colombia. The consumption of resources that is made evident represents high average annual direct medical costs, both for inpatient and ambulatory services. Even out-of-pocket expenses undertaken by the families have a high impact on their budget, mainly in families with lower incomes.

The scarcity of literature on this subject makes this study relevant, not only in Colombia but also in other low and middle income countries. In addition, it is noteworthy to highlight the incorporation of estimates on direct costs and out-of-pocket expenses, an economic burden for families which is rarely taken into account due to the difficulty in collecting this information. The estimation of costs in this study has been a comprehensive process, incorporating different sources of information to get an estimate of the data described, data bases, validation by experts, surveys to caregivers, complying with the cost estimation methodology involving the four stages previously described.

Studies on costs related with CCHDs mostly refer to the process of screening followed to detect these heart diseases, but not to the economic burden caused by these diseases as a whole. One study made by Peterson et al. ¹⁵ approached this topic, although it focused on comparing inpatient events among CCHD patients diagnosed timely and late, and not on estimating the total financial burden assigned to the disease. However, inpatient costs for the first year of life were estimated for 2011 prices, which reached $100,200 in patients diagnosed late versus a cost of $69,500 for patients timely diagnosed.

Regarding indirect costs and out-of-pocket expenses for CCHD, Connor et al. ²¹ carried out a qualitative study that explored the perceptions of parents on the costs associated with having a child with congenital heart disease regarding direct medical and non-medical costs undertaken by the family, and how this economic burden resulted in more stress and emotional impact. Mughal et al. ²² developed an observational study at a hospital in Lahore (Pakistan), and identified that 63.1% of the families contributed with the cost associated with the CHD patient’s treatment, and 12.3% of them contributed at 100%. A study by Raj et al. ²³ , conducted in India, estimated costs associated with CHD. Although not focusing specifically on CCHD, it is the study that approaches this topic more closely. The main results indicated that the connection between total inpatient expenses and the family income was 0.93 times the annual family income; the average time lost due to leave of absence by the father was 35 days and the loss of working days was 15 days on average. A quantitative estimation on the indirect costs and out-of-pocket expenses associated with CCHDs was not found in the literature.

There were some limitations in this study, mainly related with the low number of cases available due to the low prevalence of most CCHDs, a fact that hindered the collection of more data which may have led to imprecision. This situation led to having to carry out the surveys within a period of nine months. In addition, since records did not provide enough information to identify ambulatory costs, the data had to be obtained by consensus with experts.

CCHDs represent a high economic impact on the health system and families, especially on those with lower incomes. Cost analysis is a relevant topic for the health system and it requires a systematic and complex process. In this case, different primary and secondary information sources were available: data bases, surveys to caregivers and validation with experts on the topic. In addition, the bottom-up approach as a way to estimate a more real cost can be highlighted.

One of the most relevant added values included in the analysis for this study was the social perspective, which includes the measuring of indirect costs and out-of-pocket expenses. This dimension led to a larger data collection effort, more so when dealing with low-prevalence diseases. The results deriving from this study show the impact of these costs on the budgets of families when one of their members is diagnosed with a CCHD.