Comparison of severely ill patients with influenza A(H1N1)pdm09 infection during the pandemic and post-pandemic periods in Singapore.

BACKGROUND/OBJECTIVES: Singapore is a tropical country with influenza seasons occurring bi-annually. We compared the profile of severely ill patients with laboratory confirmed influenza A(H1N1)pdm09 infection in Singapore during the pandemic and post-pandemic periods, and studied their risk factors associated with mortality. PATIENTS/METHODS: Three periods were defined for this study; pandemic period from 18 June to 29 August 2009, early post-pandemic period from 30 August 2009 to 12 February 2010, and late post-pandemic period from 13 February to 10 August 2010. RESULTS: A total of 172 severely ill patients were admitted to hospitals from 18 June 2009 to 10 August 2010, of whom 23.8% died. The median age in the late post-pandemic period was significantly older than that in the early post-pandemic period (52 years versus 35 years, P=0.02). The median age of patients who died was significantly older than those who survived (52 years versus 44 years, P<0.01). The median length of stay under intensive care in the late post-pandemic period was twice that in the early post-pandemic (6 days versus 3 days, P=0.045). The proportion who died in the late post-pandemic period was more than 2.5 times that in the early post-pandemic period (29.8% versus 11.1%, P=0.043). CONCLUSIONS: Severely ill patients were of older age in the late post-pandemic period. Older age was also significantly associated with mortality. It is important to maintain heightened vigilance and continue the surveillance of severely ill patients with influenza post-pandemic, so that patients with suspected infections could be promptly identified for early diagnosis and treatment.

Differing symptom patterns in early pandemic vs seasonal influenza infections.

BACKGROUND: Singapore is a tropical country with a temperature range of 23 degrees C to 35 degrees C and relative humidity of 48% to 100% throughout the year. Influenza incidence peaks in June through July and November through January, though influenza cases can be detected throughout the year. METHODS: Between May 1 and July 28, 2009, a novel dual-gene diagnostic polymerase chain reaction assay targeting the hemagglutinin (HA) and nucleoprotein (NP) genes of the new influenza A(H1N1/2009) virus was specifically designed for enhanced influenza surveillance using nasopharyngeal swabs collected from symptomatic patients (including their close contacts) and returning travelers returning from influenza A(H1N1/2009)-affected areas, presenting to affiliated primary care clinics as well as the main hospital emergency department. RESULTS: From the week of June 16 to June 23, 2009, this pandemic influenza A(H1N1/2009) displaced and then replaced the seasonal influenzas (H3N2, H1N1, and B). Of 2683 samples tested during this 12-week surveillance period, 742 (27.6%) were positive for any influenza virus using this assay, with 547 cases of A(H1N1/2009) (20.4%), 167 cases of A(H3N2) (6.2%), 14 cases of A(H1N1) (0.5%), and 12 cases of influenza B (0.4%). Results of multivariate analysis showed that age (P < .001), fever (P < .001), cough (P < .001), sore throat (P = .002), rhinorrhea (P = .001), and dyspnea (P < .001) were significantly different among these groups. CONCLUSIONS: From this large prospective study, there was a lower incidence of fever and dyspnea in patients with pandemic influenza A(H1N1/2009) infection. Similar to reports from elsewhere, it was also found that this pandemic virus tends to infect younger people, though with fewer symptoms, on average, than seasonal influenza. Early pandemic influenza A(H1N1/2009) infections appeared to be slightly milder than seasonal influenza as indicated by different symptom patterns in the presentation of more than 500 cases of influenza A(H1N1/2009) during April through July to a large teaching hospital in Singapore.

Corticosteroid treatment of severe acute respiratory syndrome in Hong Kong.

BACKGROUND: The patterns of corticosteroids usage in severe acute respiratory syndrome (SARS) and associated treatment outcomes in Hong Kong were studied. METHOD: Patients> or =18 years old who either had not received corticosteroid or had taken corticosteroids within 14 days from symptom onset were included. Patients receiving corticosteroids beyond 15 days or other investigational treatment within 21 days from symptom onset were excluded. Of 1313 eligible patients, 1287 with major corticosteroid dosage-type combinations were analysed. RESULTS: Crude death rate was lower among 1188 steroid-treated patients compared to 99 patients in Group No Steroid (17.0% vs. 28.3%). Among four corticosteroid groups studied, mortality was lowest in the low-dose oral prednisolone (Group P) and high-dose methylprednisolone (Group MP) groups. On multivariate analysis of the corticosteroid groups, independent factors related to death were: corticosteroid group, older age, co-morbidity, worse chest X-ray score, worse respiratory status at Days 8-10 and higher admission white cell count. Again Groups P and MP had significantly lower adjusted odds ratios for death and lower bacterial and fungal culture rates. Despite worse chest X-ray scores and higher cumulative corticosteroid dosages in Group MP compared to Group P, fewer patients required rescue pulsed corticosteroid. Patients on hydrocortisone (Group HC) had the highest positive culture rates. CONCLUSION: We speculate that corticosteroid with higher in-vitro inflammatory potency administered at timing and dosages commensurate with disease severity may be conducive to better outcome from SARS as a consequence of more effective control of immunopathological lung damage.