[Clinical features and prognostic factors of parainfluenza virus infections in adult patients].

To explore the clinical features and prognostic factors of parainfluenza viral lower respiratory tract infections in adults. A total of 70 patients withpositive nucleic acid of parainfluenza virus (PIV) admitted to China-Japan Friendship Hospital between August 2016 and November 2019 were enrolled. Multiplex real-time polymerase chain reaction (RT-PCR) assays for viral detection were implemented to specimens (nasopharynx swab, sputum or bronchoalveolar lavage) obtained from all the patients, which was consistent with the diagnosis of lower respiratory tract infection. Patients were divided into two groups depending on the status of immune function (immunocompromised group, n=26; immunocompetent group, n=44), and patients were divided into PIV infection group (n=43) and mixed infection group (n=27) according to whether there was mixed infection. Characteristics including age, gender, underlying diseases, symptoms, disease severity, imaging manifestations, etiology, respiratory failure, mechanical ventilation, vasoactive drug, antimicrobial drug and 30-day mortality between the groups were compared, and the prognostic factors of PIV infections were investigated using Cox regression. The peak incidence of PIV infection time was in May, August, September and December, accounting for 58.6% of all cases. The enrolled 70 cases included 43 cases with pneumonia, 16 cases with interstitial lung disease and infection, 7 cases with bronchiectasis and infection, and 4 cases with acute exacerbation of chronic obstructive pulmonary disease. Eight patients (11.4%) had no underlying diseases, 21 patients (30.0%) had respiratory failure, 18 patients (25.7%) were treated with mechanical ventilation, 15 patients (21.4%) died within 30 days after admission. The pneumonia severity index score, percentage of patients with ground-glass opacity according CT scan, with honeycomb or reticular pattern, with mechanical ventilation, with respiratory failure, with ICU admission, and 30-day mortality in immunocompromised group were higher than those of immunocompetent group [(91.5 vs 84.0), (60.0% vs 34.1%), (44.0% vs 11.4%), (42.3% vs 15.9%), (50.0% vs 18.2%), (38.5% vs 22.7%), (34.6% vs 13.6%)] (all P<0.05). There were 27 cases (38.6%) with mixed infection, including 17 viruses (24.3%), 19 bacteria (27.1%), 14 (20.0%) fungi (PCP, aspergillus) and 1 (1.4%) Mycobacterium intracellulare. Sixteen patients (59.3%) in the mixed infection group were immunocompromised patients and 21 patients (77.8%) had chronic lung disease. Cox regression analysis showed that mechanical ventilation and interstitial lung disease were independent predictors of prognosis in all patients, and mechanical ventilation was an independent predictor of prognosis in PIV infection group. Most of the patients with PIV lower respiratory tract infection in adults are complicated with underlying diseases and mixed infection, with a high 30-day mortality. Interstitial lung disease and mechanical ventilation indicate poor prognosis in these patients.