Despite mortality rate due to HIV/AIDS falling significantly in Brazil, the northern and northeastern regions of the country have seen an increase and, between these two regions, the trend has been increasing at a greater rate in the state of Amazonas3,5. Our study found respiratory syndromes, followed by neurological and digestive syndromes, to be the main causes of hospitalization. In most of these cases, opportunistic pathogens were observed, especially TB, neurotoxoplasmosis and oropharyngeal-esophageal candidiasis. These data demonstrate that, although the country is progressing towards reaching the UNAIDS 90-90-90 treatment target, the northern and northeastern regions are no in line with the general trend. Here in the Brazilian Amazon, opportunistic infections continue to be the main causes of death of people living with HIV, which is a similar situation for those coming from cities in other regions with low economic power14–19.
Regarding the risk of death, our multivariable logistic regression model indicated two main causes of death, HIV/TB co-infection and digestive syndrome. Tuberculosis was highly prevalent in HIV/AIDS patients admitted at the FMT-HVD, as has been occurring for the past ten years5. The prevalence of HIV/AIDS co-infection can be much higher, since TB is generally paucibacillary in HIV-infected individuals, which makes diagnosis difficult7,20. As the HIV infection weakens the host's immune response to TB, HIV/TB co-infection results in a more dramatic progression7,16,17,20−22. In relation to digestive syndrome, it is worth highlighting that more than half of digestive syndromes were due to oropharyngeal-esophageal candidiasis. The occurrence of oral candidiasis has been recognized as an indicator of immune suppression. It is known that some patients did not wish to receive HAART due to skepticism, social factors, or because, even while taking medications, they experienced virological and therapeutic failure23. Here, CD4 counts lower than 200cells/ul were observed in almost all HIV-infected patients. In this context, the occurrence of oropharyngeal-esophageal candidiasis can help physicians to diagnose the clinical progression of HIV infection, as observed in other countries 24,25.
HIV/AIDS is characterized by a state of chronic hyperactivation. In this sense, several serological markers are being investigated in the search for a better predictor of the risk of death12,26–29. In the present study, no difference was observed in sCD14, IL-8 and Th1/Th2/Th17 cytokines between patients who died or were discharged. Biomarker concentrations are observable outcomes of complex biological processes that are only partially understood, and this may be the reason for a lack of consensus regarding immunological markers in prediction of mortality in HIV/AIDS patients30–34. Curiously, we observed much higher levels of inflammatory biomarkers sCD14, IL-8, and IL-6 than for other cytokines, which is consistent with the inflammatory status of the HIV/AIDS patients35. In relation to the main Th1/Th2/Th17 cytokines, the very low concentrations could be explained by immunosuppression of CD4 T cells. Thus, elevated levels of three markers are consistent with inflammatory loadings of soluble receptors, chemokines, and proinflammatory cytokines in HIV/AIDS patients27.
According to multivariable analysis, PDW was the only parameter which indicated a likelihood of death in HIV/AIDS patients. This became clearer through the trend towards a concomitant increase of PDW and MPV in patients who were discharged. MPV and PDW are easily measured platelet indexes, which increase during platelet activation. However, PDW seems to be a more specific activation marker due to the increase in the number and size of pseudopodia, under activation, and possibly affects platelet distribution width36. Platelets are small, anucleate cells that have hemostatic and inflammatory proprieties and are considered to be not so innocent bystanders. Whereas platelets appear to support the host response to extracellular infections, in intracellular infections they contribute to immune evasion37. The same authors reported that reduced platelet counts in patients with active TB are associated with mortality37. Here, some patients showed thrombocytopenia, but it was not a predictor mortality. Conversely, our multivariate analysis showed that, as the PDW values increased, the probability of death decreased. Thus, our data suggest the role of platelets as host defense effectors in agreement with these studies38–42.
The limitation of this study is related to the study design, which did not allow patient follow-up, with only one blood sample being taken after recruiting patients for the investigation of serological markers. Another limitation was that the information regarding deaths of patients was obtained solely via electronic medical records; neither did we have access to patients who evolved negatively and were admitted to the intensive care unit.
Among the immunological markers, we could not perceive any differences, as the blood collection was obtained only once and within 72 hours of admission to the hospital, though perhaps we could not distinguish them because all patients were very weak and ill. That is why it is important to perform tests on admission and a follow-up at least once right after the worsening of the state of patient, as well as another before discharge. The data collected corresponded to those closest to the day of blood collection used for the markers. No data was obtained for TB-immune reconstitution inflammatory syndrome.