Patients with malignant tumors are more likely to develop infections for various reasons[5, 6]. Therefore, we conducted this study to fully understand the clinical features of nosocomial fungal infections in patients with solid tumors and established a nomogram to predict in-hospital mortality in these patients to accurately estimate the risk of nosocomial infections death in each patient.
In the current study, 1.3% of patients with solid tumor had nosocomial fungal infections over the eight years study period, which was low compared with the results of studies before[22]. This discrepancy could be explained by the fact that the prevalence of hospital acquired infections in cancer patients varies widely from region to region. Compared with other types of tumors, patients with respiratory tumors accounted for the highest proportion of the total population (34%), followed by gastrointestinal tumors (24%) and hepatobiliary and pancreatic system tumors (24%). This may be related to the incidence of these neoplasms[23]. Meanwhile, lung cancer patients infiltrate and continuously secrete immunosuppressive factors by respiratory tumor cells, and the body's natural barrier function is inhibited, resulting in increased alveoli and bronchial secretions and mass obstruction of bronchi making lung cancer patients more susceptible to co-infection than non-lung cancer patients[24, 25].
In this study, we observed that C.Albicans is the essential microbe causing fungal infections in patients with solid tumors, accounting for 68%, followed by other Candida genera (19%). This result is consistent with the results of previous studies[11, 26]. Unfortunately, the study was retrospective, and whether patients had a swab to screen for colonizing microbiota is unknown. C.Albicans is the most common fungal infection and strain that causes invasive fungal disease. However, in recent years, studies have found that the proportion of non-C. Albicans detected in Candida and Aspergillus are increasing, and the case fatality rate is higher[27].
In this retrospective study, 76 patients (36%) received antibacterial therapy within 30 days before the diagnosis of fungal infection, the most crucial treatment received in the previous 30 days for the general population. This is consistent with our standard view: antibiotics may lead to dysbacteriosis and fungal proliferation. So patients who have previously received antibiotics need to be alert to fungal infections. Nosocomial deaths occurred in 26 of the 76 patients, accounting for 46% of the total deaths. In addition to fungal pathogenicity and invasiveness, this may also be associated with suppressed immune function in cancer patients [1, 2]. One hundred thirty-five patients received invasive procedures within 30 days of the diagnosis of fungal infection, accounting for 62% of the total population. Invasive operations such as indwelling catheterization and PICC damage the mucous membrane of the body cavity and the inner wall of blood vessels, destroying the physiological immune barrier of the human body so that fungal displacement and colonization result in infection. A prospective study published in 2018 showed a 9.1% incidence of concurrent infection of central venous catheters[3]. Therefore, patients with solid tumors should be particularly concerned about potential fungal infections when receiving antibiotic therapy or invasive procedures to avoid fungal-related deaths.
Above all, we investigated the predictors of nosocomial mortality risk of nosocomial infections in people with cancer. We found ECOG-PS 3–4, lung metastases, mechanical ventilation, thrombocytopenic, and hypoalbuminemia to be independent risk factors for in-hospital mortality. This conclusion is similar to a previous study of nosocomial mortality from bacterial infections[28]. Patients with cancer with poor ECOG-PS and distant metastases are known to be associated with adverse survival outcomes, as in our study. It recommends that we pay more attention to patients with higher ECOG-PS and those with pulmonary metastases for more refined management. Patients who received mechanical ventilation during hospitalization had a poorer prognosis, consistent with previous studies of bacterial infections[18, 21, 29, 30]. That is due to concomitant circulatory and/or respiratory dysfunction in these patients, resulting in poor clinical outcomes. We also found that patients with hypoalbuminemia and low platelets were significantly associated with higher in-hospital mortality. For one thing, because lower albumin level is often associated with immunosuppression, decreased muscle mass, malnutrition, and weight loss in patients with malignancy, these patients have a poor prognosis and an increase in cancer-related deaths[31–33]. For another, low albumin levels lead to low PNI, which one study confirmed as an independent risk factor for NSCLC[34]. At the same time, related studies have shown that thrombocytopenia is associated with a poor prognosis for many diseases[35, 36]. Our findings further confirm this view.
In this study, we developed a nomogram to predict the risk of nosocomial death from nosocomial fungal infections in cancer patients and evaluated its predictive power and clinical utility. This nomogram has good performance in predicting the risk of in-hospital death in these people. To our knowledge, this is the first study to systematically evaluate the clinical features of nosocomial fungal infections in cancer patients in northwest China and develop and validate a nomogram that can accurately predict the risk of nosocomial death from nosocomial infections in these patients. Still, there are some inevitable limits to our study. First, due to the design of the single-center retrospective analysis, it is challenging to collect variables such as specific chemotherapy and radiation doses, specific prior antibiotic treatment information, and more detailed laboratory results. Thus, there may be potential biases in the analysis of the relationships. Second, although we established a nomogram that effectively predicted the risk of in-hospital death from nosocomial infections in patients with solid tumors, internal cohort validation was not possible due to sample size, and there was a lack of independent external validation cohorts. Therefore, there is an urgent need for multi-center retrospective and well-designed prospective studies to verify the performance of nomograms.