Lower Respiratory Tract Diseases Caused by Common Respiratory Viruses among Stem Cell Transplantation Recipients: A Single Center Experience in Korea

Hong, Kyung-Wook; Choi, Su-Mi; Lee, Dong-Gun; Cho, Sung-Yeon; Lee, Hyo-Jin; Choi, Jae-Ki; Kim, Si-Hyun; Park, Sun Hee; Choi, Jung-Hyun; Yoo, Jin-Hong; Lee, Jong-Wook

RSV infections have been reported to occur in 1.2-9.6% of adult SCT recipients. 5, 17, 18 The incidences and mortality rates of RSV-LRDs among SCT recipients were reported as 2.9-5.1% and 16.7-50%, respectively. 5, 6, 14, 17 These findings are consistent with the incidence (2.7%) and mortality rate (22.5%) of RSV-LRD observed at our center, in spite of the low rate of ribavirin treatment (9.7%). Known risk factors of RSV-associated mortality in SCT patients included pre-engraftment, lymphopenia, alloSCT <1 month previously, SID, and an older age (>65 years). 14, 19 The highest incidence of RSV occurred between January and April, which is consistent with our result that the majority of RSV-LRDs were detected between December and March. 20 Symptomatic HPIV infections have been reported to occur in 1.4-7.1% of adult SCT recipients in previous studies. 5, 21, 22 The reported frequency and mortality rates of HPIV-LRDs among SCT recipients were 0.05-8.1% and 11.8-46%, respectively. 5, 6, 9, 10, [22] [23] [24] The 30-day mortality rate of HPIV-LRD at our center, 26.3% (5/19) , was similar to that of previous studies, despite the low rate of antiviral treatment (36.8%). Since HPIV showed the highest cumulative incidence of LRDs at 100 days (23.5%; 95% CI, 3.3-43.7) and 1 year (69.2%; 95% CI, 45.9-92.5) following SCT, the performance of a laboratory examination is important due to non-specific respiratory symptoms. Independent predictors of HPIV-associated death that have been reported in the literature include steroid usage, cancer status, Acute Physiology and Chronic Health Evaluation II score, LRD, infection immediately following SCT (<30 days), mismatched donor, the need for mechanical ventilation, and the presence of co-pathogens. 9, 22, 23 Similarly, high-dose steroid usage at the time of diagnosis was one of the independent predictors of death among SCT recipients with CRV-LRDs in the present study. Furthermore, the present study demonstrated that HPIV infections were most prevalent in the summer months, followed by spring, which had been reported previously. 9, 22 Previous studies reported that the incidence of HRhV-LRD among SCT recipients is rare (0-1.4%), and that HRhV-LRDs are associated with low mortality rates. 5, 25 In the present study, the incidence of HRhV-LRD was 0.7% (7/1038 patients) and the associated 30-day mortality rate was 14.3% (1/7 patients). These results are consistent with the preceding studies that HRhV may cause severe infections in SCT recipients, with high rates of progression to LRD and mortality. 18, 26, 27 Ison, et al. 28 reported that all 6 SCT recipients with pneumonia in whom HRhV was detected in BAL had significant coinfections and suggested that HRhV might be a cause of frequent superinfections, possibly through lytic infection or an indirect immunosuppressive effect. Our study also indicated that 42.9% (3/7) of patients with HRhV-LRDs were positive for the presence of copathogens.