48 COVID-19 and H1N1 Pneumonia: Reanalysis and Comparison of Two Cohorts

Abstract

BackgroundInfluenza A H1N1 and SARS-CoV2 have been responsible for important viral respiratory disease epidemics in the 21st century. Both diseases (H1N1 flu and COVID-19) usually present with upper respiratory infection and may evolve into pneumonia. This study evaluated similarities and differences between these viral epidemics in hospitalized patients.MethodsThis is a reanalysis of retrospectively enrolled cohorts in a tertiary hospital (in São Paulo, Brazil) during two different types of viral respiratory epidemics. All RT-PCR confirmed H1N1 patients originally enrolled from July 12 to August 17, 2009 were included. We paired these patients by sex and age 1:1 using propensity score matching with our COVID-19 database of patients, which includes RT-PCR confirmed COVID-19 patients from March 2020 to March 2021. The primary outcome was hospital death. We analyzed the following variables as secondary outcomes: ICU care, ICU length of stay, signs and symptoms at admission, vitals at admission and 72h blood tests. We used R software version 4.2.0 for statistical analysis (significance at 0.05).ResultsWe included 52 H1N1 patients and 52 matched COVID-19 patients. Enrolled patients were on average 41 years old and 41% were female. Regarding the primary outcome, hospital death was more common for COVID-19 patients (10% vs 31%, p=0.007). ICU care was more common for COVID-19 patients (52% vs 89%, p<0.001), and ICU stay was longer for them (1 vs 10 days, p<0.001). Cold symptoms, including fever (92% vs 65%, p=0.001), sputum (25% vs 4%, p=0.003), coryza (79% vs 19%, p<0.001) and odynophagia (39% vs 11%, p=0.002) were more common in H1N1 patients. There was no difference in heart (100 vs 98, p=0.738) or respiratory (28 vs 26, p=0.284) rate, but peripheral oxygen saturation (90% vs 93,5%, p<0.001), systolic (110 vs 129, p=0.039) and diastolic (61.3 vs 75.5, p=0.011) blood pressure were higher in COVID-19 patients at admission. 72-hour blood tests showed higher leukocytes (7055 vs 8975, p=0.037) and c-reactive protein (72 vs 167, p<0.001) in COVID-19 patients but higher lymphocytes (1100 vs 975, p=0.022), hematocrit (39.5 vs. 34.45, p=0.028), and lactic dehydrogenase (668.5 vs 436, p<0.001) in H1N1 patients. Finally, there was no difference in platelet (182000 vs 200500, p=0.265) or creatine phosphokinase (117 vs 112, p=0.969) levels.Discussion & ConclusionsThese results reveal that H1N1 and COVID-19 present very different clinical conditions and exam results. On the one hand, H1N1 presented much closer to an influenza-like illness than COVID-19. On the other hand, COVID-19 had a rate of ICU admission with longer stays and higher mortality. These findings are despite H1N1 patients having worse initial vitals with lower blood pressures and peripheral oxygen saturation. Considering COVID-19 may become an endemic variety of respiratory virus, knowledge of different presentations and lab profiles will make it easier to classify disease probability in patients coming to the emergency department.Trial RegistrationThis study was registered as RBR-5d4dj5 at ensaiosclinicos.gov.brFundingFAPESP and the hospital in which the study was conducted funded this study.Ethical approval and informed consentThe study protocol was approved by the local Ethics Committee (opinion number 3.990.817; CAAE: 30417520.0.0000.0068), which waived the need for written informed consent. We adhere to STROBE guidelines.No, authors do not have interests to disclose BackgroundInfluenza A H1N1 and SARS-CoV2 have been responsible for important viral respiratory disease epidemics in the 21st century. Both diseases (H1N1 flu and COVID-19) usually present with upper respiratory infection and may evolve into pneumonia. This study evaluated similarities and differences between these viral epidemics in hospitalized patients. Influenza A H1N1 and SARS-CoV2 have been responsible for important viral respiratory disease epidemics in the 21st century. Both diseases (H1N1 flu and COVID-19) usually present with upper respiratory infection and may evolve into pneumonia. This study evaluated similarities and differences between these viral epidemics in hospitalized patients. MethodsThis is a reanalysis of retrospectively enrolled cohorts in a tertiary hospital (in São Paulo, Brazil) during two different types of viral respiratory epidemics. All RT-PCR confirmed H1N1 patients originally enrolled from July 12 to August 17, 2009 were included. We paired these patients by sex and age 1:1 using propensity score matching with our COVID-19 database of patients, which includes RT-PCR confirmed COVID-19 patients from March 2020 to March 2021. The primary outcome was hospital death. We analyzed the following variables as secondary outcomes: ICU care, ICU length of stay, signs and symptoms at admission, vitals at admission and 72h blood tests. We used R software version 4.2.0 for statistical analysis (significance at 0.05). This is a reanalysis of retrospectively enrolled cohorts in a tertiary hospital (in São Paulo, Brazil) during two different types of viral respiratory epidemics. All RT-PCR confirmed H1N1 patients originally enrolled from July 12 to August 17, 2009 were included. We paired these patients by sex and age 1:1 using propensity score matching with our COVID-19 database of patients, which includes RT-PCR confirmed COVID-19 patients from March 2020 to March 2021. The primary outcome was hospital death. We analyzed the following variables as secondary outcomes: ICU care, ICU length of stay, signs and symptoms at admission, vitals at admission and 72h blood tests. We used R software version 4.2.0 for statistical analysis (significance at 0.05). ResultsWe included 52 H1N1 patients and 52 matched COVID-19 patients. Enrolled patients were on average 41 years old and 41% were female. Regarding the primary outcome, hospital death was more common for COVID-19 patients (10% vs 31%, p=0.007). ICU care was more common for COVID-19 patients (52% vs 89%, p<0.001), and ICU stay was longer for them (1 vs 10 days, p<0.001). Cold symptoms, including fever (92% vs 65%, p=0.001), sputum (25% vs 4%, p=0.003), coryza (79% vs 19%, p<0.001) and odynophagia (39% vs 11%, p=0.002) were more common in H1N1 patients. There was no difference in heart (100 vs 98, p=0.738) or respiratory (28 vs 26, p=0.284) rate, but peripheral oxygen saturation (90% vs 93,5%, p<0.001), systolic (110 vs 129, p=0.039) and diastolic (61.3 vs 75.5, p=0.011) blood pressure were higher in COVID-19 patients at admission. 72-hour blood tests showed higher leukocytes (7055 vs 8975, p=0.037) and c-reactive protein (72 vs 167, p<0.001) in COVID-19 patients but higher lymphocytes (1100 vs 975, p=0.022), hematocrit (39.5 vs. 34.45, p=0.028), and lactic dehydrogenase (668.5 vs 436, p<0.001) in H1N1 patients. Finally, there was no difference in platelet (182000 vs 200500, p=0.265) or creatine phosphokinase (117 vs 112, p=0.969) levels. We included 52 H1N1 patients and 52 matched COVID-19 patients. Enrolled patients were on average 41 years old and 41% were female. Regarding the primary outcome, hospital death was more common for COVID-19 patients (10% vs 31%, p=0.007). ICU care was more common for COVID-19 patients (52% vs 89%, p<0.001), and ICU stay was longer for them (1 vs 10 days, p<0.001). Cold symptoms, including fever (92% vs 65%, p=0.001), sputum (25% vs 4%, p=0.003), coryza (79% vs 19%, p<0.001) and odynophagia (39% vs 11%, p=0.002) were more common in H1N1 patients. There was no difference in heart (100 vs 98, p=0.738) or respiratory (28 vs 26, p=0.284) rate, but peripheral oxygen saturation (90% vs 93,5%, p<0.001), systolic (110 vs 129, p=0.039) and diastolic (61.3 vs 75.5, p=0.011) blood pressure were higher in COVID-19 patients at admission. 72-hour blood tests showed higher leukocytes (7055 vs 8975, p=0.037) and c-reactive protein (72 vs 167, p<0.001) in COVID-19 patients but higher lymphocytes (1100 vs 975, p=0.022), hematocrit (39.5 vs. 34.45, p=0.028), and lactic dehydrogenase (668.5 vs 436, p<0.001) in H1N1 patients. Finally, there was no difference in platelet (182000 vs 200500, p=0.265) or creatine phosphokinase (117 vs 112, p=0.969) levels. Discussion & ConclusionsThese results reveal that H1N1 and COVID-19 present very different clinical conditions and exam results. On the one hand, H1N1 presented much closer to an influenza-like illness than COVID-19. On the other hand, COVID-19 had a rate of ICU admission with longer stays and higher mortality. These findings are despite H1N1 patients having worse initial vitals with lower blood pressures and peripheral oxygen saturation. Considering COVID-19 may become an endemic variety of respiratory virus, knowledge of different presentations and lab profiles will make it easier to classify disease probability in patients coming to the emergency department. These results reveal that H1N1 and COVID-19 present very different clinical conditions and exam results. On the one hand, H1N1 presented much closer to an influenza-like illness than COVID-19. On the other hand, COVID-19 had a rate of ICU admission with longer stays and higher mortality. These findings are despite H1N1 patients having worse initial vitals with lower blood pressures and peripheral oxygen saturation. Considering COVID-19 may become an endemic variety of respiratory virus, knowledge of different presentations and lab profiles will make it easier to classify disease probability in patients coming to the emergency department.