This is, to our knowledge, the first estimate of the social burden of RSV in children under age two years in Colombia. We found that only RSV infection in children less than 2 years generates more DALYs than estimated previously for all LRTI in Colombia; differences at least from methodological view were due to differences in sources of information, but also show the real burden of disease of this infection in our society.
Respect to the difference to another burden of disease studies in our country, the global burden study estimated that LRTI accounts for around 14.1% of DALYs in children less than 4 years worldwide for example (1). In Colombia, this percentage was 6.35% (9.9 DALYs per 1000 in children less than 4 years and 3.98 DALYs per 1000 in children less than 2 years) (14). But our estimate is higher (was 20 DALYs / 1000 person-year (95% CI 16–27), and only included RSV. The national burden of disease study used data from national health surveys while we examined the records of epidemiological surveillance. Our records have a greater degree of completeness since they are mandatory in Colombia, and are completed by the physicians and this tendency of a discrepancy of results has been seen before with other estimation of DALYs (15, 16).
Otherwise, if RSV infection alone generates 20 DALYs for 1000 children under 2 years of age, this disease would be only behind of low birth weight in the total estimation of DALYs in this age group. This finding is consistent with studies in the hospital setting where document the large amount of morbidity generated by RSV and acute bronchiolitis (5). Most of DALYs (63.19%) were generated by children between 1–2 years, due to the greater amount of YLL lost. Indeed, 99% of DALYs were caused by YLD which have more weight in estimating the DALYs while YLL are not weighted by disability weights. Similarly, the mortality rates in Latin America by RSV, also were higher in children between 1–2 years (17). It's possible to explain this by a possible considerable delay in medical consultation of severe cases of RSV infection in this age group, respect to younger children; due to attitude, more "relaxed" by parents in this patients. Further a greater tendency to self-medication, aspects which affect the mortality rate (17).
When we compare our results with other estimations of DALYs of different diseases, RSV infection in children under age two years, generates more years of life lost than cervical cancer between 45–59 years (1.6 DALYs per 1000 inhabitants), epilepsy between 30–44 years (1 DALYs per 1000 inhabitants) and leukemia in children between 5–14 years (1 DALYs per 1000 inhabitants)(14). This highlights the importance of generating specific burden of the disease studies by etiological agent, but also that it should encourage the development of vaccines; which according to our estimates would have a high population impact. Burden of disease studies should be a primary source for prioritization exercises in public health. Although in our continent even the use of health technology assessment and advanced statistical information is not the main input for decision-making, this type of estimations such as ours should encourage decision-makers to use evidence to make health decisions(18).
This study has limitations. First, we may have some degree of information bias and underestimation due to the use of data from the national surveillance and notification system (19). However, LRTI cases have florid symptomatology in this age group, often prompting medical attention. There are a global increasing in the reporting of cases to SIVIGILA has been noted (20), and in our sensitivity analysis, the final result of DALYs was not sensitive to the change in values of these probabilities, guaranteeing the robustness of the model. There are no specific "disability weights" for RSV infection. In this case, we used data reported for LRTI because in terms of mortality it does not differ from data presented by patients with other viruses in Colombia (11). In the sensitivity analysis, the percentage of change in the total estimate of DALYS did not exceed 25% within the variables analyzed.