key: cord-1048045-mai4eggf
authors: Bai, Lu; Gu, Li; Cao, Bin; Zhai, Xiao-Li; Lu, Min; Lu, Yong; Liang, Li-Rong; Zhang, Lei; Gao, Zi-Fen; Huang, Ke-Wu; Liu, Ying-Mei; Song, Shu-Fan; Wu, Lin; Yin, Yu-Dong; Wang, Chen
title: Clinical Features of Pneumonia Caused by 2009 Influenza A(H1N1) Virus in Beijing, China
date: 2015-12-16
journal: Chest
DOI: 10.1378/chest.10-1036
sha: 5ce430242bc6674c68d00110511cd1da4f53b265
doc_id: 1048045
cord_uid: mai4eggf

BACKGROUND: Data on symptoms and radiographic changes in patients with pandemic 2009 influenza A(H1N1) (A[H1N1]) pneumonia during convalescence have not been reported. METHODS: During October 26, 2009, and January 23, 2010, adult patients with pneumonia with laboratory-confirmed or clinically suspected A(H1N1) infections were observed for clinical characteristics, high-resolution chest CT scan, and lung function test changes during acute and 3-month convalescent phases. RESULTS: Of the 65 case subjects, the median age was 41 (interquartile range [IQR], 28-57) years, 60.0% were men, and 55.4% had at least one underlying medical condition. Sixty-two patients started oseltamivir therapy within a median of 5 (IQR, 4-6) days from the onset of illness, and 31 received IV corticosteroids. ARDS developed in 33 patients, and 24 were treated initially with noninvasive positive pressure ventilation (NPPV). In this group, NPPV was successful in 13 patients (54.2%). Nine patients died at a median of 16 (IQR, 10-24) days after onset of illness. Multivariate Cox regression identified two independent risk factors for death: progressive dyspnea after resolution of fever (relative risk, 5.852; 95% CI, 1.395-24.541; P = .016) and a higher APACHE (Acute Physiology and Chronic Health Evaluation) II score on presentation (relative risk for each point, 1.312; 95% CI, 1.140-1.511; P < .001). At 3-month follow-up of survivors with A(H1N1), ground-glass opacities were still present, although diminished, in 85.7%, and diffusing capacity for carbon monoxide was mildly reduced in 61.5%. CONCLUSIONS: Ground-glass opacities and decreased diffusing capacity were the main abnormalities observed at 3-month follow-up of survivors of A(H1N1).

The clinical spectrum of this disease has ranged from self-limited illness to respiratory failure and death. 1 In our initial report of the A(H1N1) virus infection in China, the majority of patients had mild illness. 2, 3 Since the fi rst report of pneumonia caused by the A(H1N1) virus in Mexico, 4 severe cases have been documented throughout the world. As of March 7, 2010, Ն 16,713 laboratoryconfi rmed cases of death have been reported by the six world regions. 5 In mainland China, there were . 127,000 confi rmed cases up to February 28, 2010, including 793 deaths. 6 Many studies have been published on the clinical manifestations of A(H1N1) pneumonia during the acute phase of illness, [7] [8] [9] [10] [11] [12] [13] [14] [15] but no information has been reported on symptoms and radiographic and lung function changes in convalescence. We studied clinical manifestations during the acute phase, antiviral and corticosteroid therapy, noninvasive positive pressure ventilation (NPPV), and the histopathologic changes of a fatal case. Survivors were followed up after discharge for a period of 3 months. We believe Patient follow-up and further investigation at follow-up were carried out according to clinical need, so written informed consent was not sought. High-resolution CT (HRCT) scanning was ordered only in those with persisting symptoms, chest signs, or radiologic fi ndings on discharge or on last visit. No contrast was given with CT scan, and the possible radiation harm was also explained to patients. Lung function tests (LFTs) were ordered in those patients still attending at 3 months. The ethics board committee at Beijing Chao-Yang Hospital approved the study design.

The severity of lung changes was evaluated initially and on follow-up examinations. Each lung was divided into three zones. 16 The number of abnormal zones and the changes in ground-glass opacities (GGOs), consolidation, reticular-nodules, and interlobular septal thickening were evaluated by HRCT scanning. All evaluations were performed by two radiologists who were blinded to the clinical information.

LFTs, including lung volume, spirometry, and diffusing capacity for carbon monoxide (D lco ) were performed 3 months after the onset of symptoms. All LFTs were performed in accordance with recommended standards. D lco was measured with a singlebreath technique, adjusted for hemoglobin and alveolar volume. LFT measurements were considered abnormal if they were , 80% of the predicted value.

Continuous variables were summarized as means ( 6 SD) or medians (interquartile range [IQR] ). Differences between groups were assessed using the x 2 test or Fisher exact test for categorical variables and the Mann-Whitney U test for continuous variables. We used univariate and multivariate Cox regression to identify independent predictors of mortality. All analyses were performed by SPSS software,version 13.0 (SPSS Inc; Chicago, Illinois). A P value Յ .05 was considered statistically signifi cant.

From October 26, 2009, to January 23, 2010, a total of 2,415 cases of infl uenza-like illness were reported in our hospital, of which 516 were laboratory-confi rmed A(H1N1) cases. During the epidemic, a total of 65 patients were eligible for this study, including 62 patients with laboratory-confi rmed A(H1N1) and three patients with high clinical suspicion for A(H1N1) infection. Among the 65 patients, 50 were hospitalized, and 15 were treated as outpatients.

Median age was 41 years, 60.0% were men, and 55.4% had at least one underlying medical condition ( Table 1 ) . Dyspnea persisted in 13.8% of patients after resolution of fever. Smokers were more common in the ARDS group ( P 5 .067), and moist rales and wheezing were signifi cantly more frequent in this group. Although leukocyte counts were similar in the two our work can help optimize treatment, and also lead to a better understanding of the symptomatic, radiologic, and lung functional changes during the convalescent period.

Data were collected retrospectively and prospectively on all patients with confi rmed A(H1N1)-related pneumonia treated at Beijing Chao-Yang Hospital between October 26, 2009, and January 23, 2010. The diagnosis of pneumonia was based on respiratory symptoms combined with a new infi ltrate on chest radiograph. Real-time reverse transcriptase polymerase chain reaction (RT-PCR) assay was used to confi rm the diagnosis of A(H1N1) infection. Patients presenting with pneumonia with high clinical suspicion of A(H1N1) infection but negative RT-PCR test results for A(H1N1) were also included in this study. Children younger than 14 years of age were excluded. Most patients were hospitalized for treatment, whereas those who presented with less serious illness and did not need oxygen supplementation were treated as outpatients under home quarantine.

Treatment decisions for all patients were made by their attending physicians. Hospitalized patients were discharged when their temperatures had returned to normal for at least 3 days, most infl uenza-like symptoms had disappeared, and they were clinically stable.

Information recorded included demographic data, underlying medical conditions, symptoms, signs, laboratory and chest radiograph fi ndings before therapy and during follow-up, and the clinical course, treatment, and adverse events during hospital stay. APACHE (Acute Physiology and Chronic Health Evaluation) II scores were determined in all patients to assess the severity of illness. During hospitalization, clinical data were collected retrospectively from medical records. zones on chest radiograph ( P 5 .002) than did those who were outpatients.

Sixty-two of 65 patients started oseltamivir therapy within a median of 5 (IQR, 4-6) days from the onset of illness. Dosages and duration of antiviral therapy are listed in Table 1 . Thirty-one patients received IV corticosteroids for a median duration of 3 (IQR, 3-6) days, with a dose of methylprednisolone, 1-3 mg/kg/d.

Adverse effects involving hallucinations and disorientation occurred in three male hospitalized patients 24 to 36 h after beginning corticosteroids or oseltamivir. Two of the three patients received both drugs, and the other one received only oseltamivir. Symptoms groups, lymphocyte counts were signifi cantly lower and serum potassium levels signifi cantly higher in the ARDS group. Patients with ARDS also required more frequent use of higher doses of oseltamivir, longer duration of oseltamivir treatment, and more frequent use of corticosteroids and vasopressors, and more frequently had positive bacterial and fungal cultures. The most common initial radiologic fi ndings on HRCT scan were bilateral GGOs involving several zones with or without associated multifocal areas of consolidation. Centrilobular nodules were also common, and small pleural effusions were present in 25.7% of patients ( Fig 1 ) . In patients without ARDS, those who were hospitalized more frequently had diarrhea ( P 5 .003), moist rales ( P 5 .001), a lower serum albumin level ( P 5 .011), and more involved lung ; without ARDS group (n 5 25); with ARDS group (n 5 33). g Chest radiograph was performed within 1 wk after onset of symptoms. Total (N 5 57); without ARDS group (n 5 29); with ARDS group (n 5 28). h High-resolution chest CT scanning was performed at a median 6 (interquartile range, 4-9) days after onset of symptoms. Total (N 5 35); without ARDS group (n 5 14); with ARDS group (n 5 21). disappeared 1 to 2 days after stopping corticosteroids and oseltamivir or lowering the dose of oseltamivir.

Among 33 patients with ARDS, 24 required ventilation support, all of whom were initially treated with NPPV. In this group, NPPV succeeded in 13 (54.2%) (duration 5.1 6 2.8 days) and 10 (41.7%) failed and were intubated at a median of 16 (IQR, 10-84) h after admission; the last one refused intubation and died. Among the 10 patients who were intubated, eight died. Patients who failed NPPV treatment had higher APACHE II scores on presentation (median 13 [IQR, [11] [12] [13] [14] ) compared with those who succeeded Table 4 ) , who was treated successfully with oseltamivir and noninvasive positive pressure ventilation. A, Initial high-resolution CT (HRCT) scan obtained 12 days after onset of illness shows bilateral extensive ground-glass opacities (GGOs) and multifocal consolidation that had a predominant subpleural distribution. B, HRCT scan obtained 29 days after onset of illness shows GGOs, interlobular septal thickening, and reticular nodules pattern (arrows). C, On day 54, only GGOs are seen. D, At a 3-month visit, GGOs are still present but are much improved. E and F, The same scan as A shows centrilobular nodules in the left upper lobe (arrows in E) and a very small amount of right pleural effusion (arrow in F).

(median 10 [IQR, [9] [10] [11] ; P 5 .020). Barotrauma occurred in two patients, one during extracorporeal membrane oxygenation therapy.

Sputum or transtracheal aspirate specimens obtained for bacterial culture were positive in 13 patients ( Table 1 ) , including Acinetobacter baumannii, four; Klebsiella pneumoniae, four; Pseudomonas aeruginosa, two; Enterobacter aerogenes , one; Escherichia coli, one; Staphylococcus aureus, one; and A spergillus spp, six . Only one patient had a positive sputum culture within the fi rst 48 h of hospitalization ( Klebsiella pneumoniae ). All other positive bacterial or fungal cultures were obtained Ն 48 h after hospitalization.

An autopsy was performed on a 44-year-old previously healthy man who was admitted 7 days after onset of symptoms and died of severe ARDS on day 18 of hospitalization ( Fig 2 ) . Gross examination of lung tissue revealed prominent congestion and consolidation, with increased weight (left, 860 g; right, 1,178 g). An abscess was seen in the right lower lobe that 

Among the 65 patients, nine died, of whom eight had hemorrhagic respiratory secretions. One 19-yearold man died of severe hemoptysis within 24 h of admission. The death rate among patients with ARDS was 27.3% (9/33). The main cause of death was refractory hypoxemia. Two factors were found to be independently associated with death: progressive dyspnea after resolution of fever (relative risk, 5.852; 95% CI, 1.395-24.541; P 5 .016) and a higher APACHE II score on presentation (relative risk for each point, 1.312; 95% CI, 1.140-1.511; P , .001) ( Table 2 ) .

Of the 56 survivors, 39 had one or more follow-up visits. Among 14 who completed the 3-month visits, symptoms reported at the last visit included exertional dyspnea (four), hair loss (two), and cough (one). The duration of symptoms was as follows: sputum 19.6 6 6.6 days, bloody sputum 11.0 6 4.1 days, fatigue 16.0 6 7.7 days. A 31-year-old female patient who was previously healthy still had a low platelet count of 34,000 per mm 3 at 75 days after the onset of illness.

Changes in lung abnormalities from initial to follow-up HRCT scan examinations are shown in Table 3 . Among the 14 patients who completed their 3-month visit, 12 still showed lesser degrees of GGOs ( Fig 1 ) . In those who had ARDS (n 5 9), "involved zones" were signifi cantly ( P 5 .002) more frequent than in those without ARDS (n 5 5).

LFTs were performed at visit 3 for 13 patients ( Table 4 ). All 13 had been hospitalized, and there was no statistical difference in clinical and laboratory characteristics between these patients and those in whom LFTs were not obtained. Impairment of D lco was the most common (8/13 [61.5%]) abnormality detected. Data are presented as median (interquartile range) unless otherwise indicated. A(H1N1) 5 2009 infl uenza A(H1N1). See Table 1 

Our series of 65 cases of A(H1N1) identifi ed two independent risk factors associated with fatal pneumonia: progressive dyspnea after resolution of fever and a higher APACHE II score on presentation. Three months later, GGOs of less severity were still present on chest radiographs in 85.7% of patients (12/14) . LFTs revealed decreased D lco ( , 80% predicted) in eight (61.5%) of the 13 patients tested.

The clinical characteristics of A(H1N1) pneumonia we described during the acute phase were similar to those reported by others. [8] [9] [10] [11] [12] [13] [14] [15] In this report, most patients complained of dyspnea, which usually occurred within 1 week after illness onset. Dyspnea continued to progress after resolution of fever in 13.8% of the patients, a fi nding that has not been reported by others.

In this report, the success rate for NPPV was 54.2%, which is much higher than that reported by others (14.5%-27.3%). 7, [12] [13] [14] Although the death rate (8/10 [80%]) in patients who received invasive ventilation in our study was higher than that reported in another study, 7 among patients with ARDS, the death rate was 27.3%, similar to other reports. 7, 8, [11] [12] [13] [14] [15] Moreover, although NPPV was used widely in the ward specifi cally set aside for patients infected with A(H1N1), none of the 28 doctors and nurses who were in direct contact with these patients developed respiratory symptoms or infl uenza-like illnesses. Therefore, we believe that with proper infection-control procedures, NPPV can be used successfully and safely for treating patients with A(H1N1) pneumonia complicated by ARDS.

It has been reported that 29% to 55% of autopsied patients with A(H1N1) had evidence of bacterial coinfection. 17, 18 Streptococcus pneumoniae, Streptococcus pyogenes , and S aureus were the most predominant pathogens. However, in our study, community-acquired bacterial infection (defi ned as sputum collected within 48 h of hospitalization) was detected in only one of 50 patients ( K pneumoniae ). The low yield of gram-positive bacteria before or within 48 h of hospitalization may be due to the widespread use of prophylactic antibiotic therapy. In contrast, nosocomial infection was common in the patients (12/50 [24.0%]), and gram-negative bacilli were the predominant causative pathogens. Aspergillus spp was also seen. Progressive A(H1N1) infection, intubation, a prolonged hospital stay, IV antibiotic use, and use of oral or IV corticosteroids may be risk factors for nosocomial infection caused by gram-negative bacilli and Aspergillus spp.

We showed that symptoms and laboratory abnormalities in survivors of A(H1N1) virus infection returned to normal within 1 month of the onset of illness. Nonetheless, GGOs were still found at 3 months, although no fi brotic changes were seen. In survivors of A(H5N1) virus infection, persistent radiologic abnormalities including GGOs, often with a reticular pattern, have been seen as long as 1 year after illness onset. 19 In survivors of severe acute respiratory syndrome (SARS) followed for 1 year, marked improvements in pulmonary fi brosis have been seen, but some patients still had residual changes. 20 Because this kind of fi brosis was reversible, it has been suggested that these fi ndings were partially caused by postinflammatory atelectasis rather than by genuine fi brosis alone. 21 The resolution of lung abnormalities in patients with A(H1N1) viral pneumonia seemed better than that seen in patients with SARS and infl uenza A(H5N1) infection. Impairment of D lco was the most common (8/13 [61.5%]) abnormality in lung function testing 3 months after the onset of illness, followed by restrictive defects (2/13 [15.4%] ). The D lco fi ndings were similar to the fi ndings of one study of patients with SARS at 3-month follow-up visits. 22 The impairment of D lco in survivors of SARS persisted for 1 year in 23.7% of patients reported by other investigators. 23 Although the number of cases with LFTs in our series is limited (only 13 cases, of whom eight had a reduction of D lco ), it seemed that patients who had bilateral GGOs on HRCT scan were more likely to have an impaired D lco . During the convalescent period of ARDS, GGOs may consist of intralobular fi brosis that is below the limits of resolution of HRCT scanning. 24 A longer follow-up study is needed to determine whether lung function abnormalities in patients infected with A(H1N1) are irreversible and radiologic changes persist over time.

To our knowledge, this is the fi rst report of symptoms and radiographic changes in patients with A(H1N1) pneumonia during the convalescent period. There were several limitations. First, it is a singlecenter study with a limited number of patients. Second, monthly follow-up visits were offered to all patients when they were discharged but some of the patients felt that was inconvenient and did not come back. As a result, 39 out of 56 survivors had one or more follow-up visits. Third, most patients had underlying medical conditions that could have contributed to the lung function abnormalities.

In conclusion, we found that progressive dyspnea after resolution of fever and a higher APACHE II score on presentation were independent risk factors associated with death in patients with A(H1N1) viral pneumonia. At the 3-month follow-up visit of survivors of A(H1N1) pneumonia, some degree of GGOs persisted in most patients and decreased D lco was common.

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Author contributions: Dr Bai: contributed to data collection and analysis and the fi rst draft of the manuscript. Dr Gu: contributed to data collection and analysis. Dr Cao: contributed to data collection and analysis, the fi rst draft of the manuscript, and revision of the manuscript . Dr Zhai: contributed to radiologic evaluation and review and revision of the manuscript. Dr M. Lu : contributed to postmortem examination and review and revision of the manuscript. Dr Y. Lu: contributed to lung function testing and review and revision of the manuscript. Dr Liang: contributed to statistical analysis and review and revision of the manuscript. Dr Zhang: contributed to radiologic evaluation and review and revision of the manuscript. Dr Gao: contributed to postmortem examination and review and revision of the manuscript. Dr Huang: contributed to lung function testing and review and revision of the manuscript. Dr Liu: contributed to infl uenza virus testing and review and revision of the manuscript. Dr Song: contributed to data collection and review and revision of the manuscript. Dr Wu: contributed to data collection and review and revision of the manuscript. Dr Yin: contributed to data collection and review and revision of the manuscript. Dr Wang: contributed to data analysis and careful revision of the manuscript. Financial/nonfi nancial disclosures: The authors have reported to CHEST that no potential confl icts of interest exist with any companies/organizations whose products or services may be discussed in this article . Other contributions: All work was performed at the Beijing Chao-Yang Hospital, Capital Medical University and the School of Basic Medical Sciences, Peking University, Bejing, China. We