This study sought to investigate the incidence, risk factors, predictors, and prognosis of CMV reactivation in immunocompetent mechanical ventilation patients. We have found that, among immunocompetent patients with mechanical ventilation, the CMV reactivation incidence was 18.3%. Clinical features, including body weight, BMI, sepsis, and biochemical indicators (NT-proBNP, BUN, Hb level) were associated with the development of CMV reactivation. Further statistical analysis showed that BMI, Hb, and sepsis had predictive value and were independent risk factors for CMV reactivation. In addition, CMV reactivation could lead to several adverse outcomes.
CMV reactivation has been a frequent phenomenon among patients admitted to the ICU. A 1990–2016 systematic review and meta-analysis review that included cohort studies estimated the incidence of CMV reactivation to be 31% in immunocompetent patients (95%CI, 24–39%) in critical care settings [12]. Similarly, a recent study that enrolled 55 patients with non-immunosuppressed cirrhosis demonstrated that the cumulative incidence of active CMV infection was 30.9% at 7-day follow-up, and the incidence rate (or density) of active CMV infection was 2.75% per person-day during the 21-day follow-up [13]. However, in another observational study on critically ill patients with sepsis, CMV reactivation incidence reached 17.9% [14]. Our finding of the lower incidence of CMV reactivation in patients with immunocompetent critically ill compared with most studies might have been attributable to ethnic differences. The inclusion criteria for studies are more stringent to screen out non-immunosuppressed patients. Also, the detection methods (samples, time points, and monitoring periods) of CMV in different studies and the selection of different diseases as subjects may be related to the incidence of CMV reactivation.
Previous studies had demonstrated that sepsis was associated with the development of CMV reactivation [4, 5, 15, 16], which was consistent with our results. Sepsis can induce CMV reactivation mainly through sepsis-related cytokine storm triggering transcriptional CMV replication, a mechanism that has been confirmed in animal models [4, 17, 18]. Several studies have shown that CMV infection can impair the cardiac and renal function, increasing cardiac and renal biochemical indicators [19, 20], which is consistent with this study’s results. The reason beyond this association is related to the direct pathological damage caused by CMV infection and indirect damage caused by inflammatory factors. Recent studies have shown that CMV infection can affect the body’s development and metabolic level and induce metabolic syndrome, which manifests as a chronic consumptive condition [21]. It can cause abnormal growth and development of the fetus and decrease lipids, BMI, and hemoglobin in adults [22, 23]. Our study found that the height, weight, and hemoglobin levels of the CMV reactivation group were lower, which may be related to CMV reactivation’s metabolic disorder.
Many studies have explored the risk factors for CMV reactivation. A meta-analysis [24] suggested that CMV reactivation was strongly associated with sepsis, mechanical ventilation, and hypertension induced by glucocorticoids and catecholamines. However, there was no correlation for disease scores, such as the APACHE and SOFA scores. Simultaneously, there was no evidence that CMV reactivation was age-related, but whether it was gender-related or not remained inconsistent. Besides, several clinical studies predicted CMV reactivation by cytokine levels (such as IL-6, IL-10, and TNF-α) [11, 14]. However, the current results were mostly negative, and no consistent results were found, which was similar to our study results. The reason may be related to the clinical condition’s complexity, and it is difficult to analyze the relationship between the immune system and CMV reactivation.
We found that BMI, Hb, and sepsis were independent risk factors for CMV reactivation through a multivariate logistic regression model. It was further found that BMI and Hb levels had a moderate value for predicting CMV reactivation. There is no relevant study consistent with our results. These results suggested that nutritional status [22] in critically ill patients might be associated with CMV reactivation, but more patients need to be included for further confirmation.
Most of the findings suggested that CMV reactivation can seriously affect the clinical prognosis of non-immunosuppressed patients, which is consistent with our findings, including prolonged duration of mechanical ventilation & ECMO, increased incidence of nosocomially acquired infections, and increased length of hospitalization and mortality, among others. [4–9, 11–15, 24, 25]. The causes of these adverse prognoses are various, including direct injury (such as CMV pneumonia) and indirect injury (such as immune disorder) [4].
Nonetheless, these results must be interpreted with caution and several limitations should be borne in mind. First, this study was a single-center observational study. The number of patients included was relatively insufficient to comprehensively evaluate CMV’s epidemiological characteristics with developing countries’ (Chinese) critically ill patients. Second, the number of patients with sepsis was insufficient for subgroup analysis. Third, some patients had CMV reactivation on the day of ICU admission, presumably before ICU admission, which might impact outcomes. Fourth, the capacity to incorporate multivariate logistic regression models was low, decreasing in statistical fitness.