Influenza A (H1N1) 2009 pandemic: was there a difference in the two waves in patients requiring admission to the intensive-care unit?

Characteristics and outcome of ill critical patients with influenza A infection

INTRODUCTION

To describe all patients admitted to Tunisian intensive care unit with a diagnosis of influenza A/H1N1 virus infection after the 2009 influenza pandemic and to analyse their characteristics, predictors of complications and outcome.

METHODS

All patients with influenza > 18-years-old hospitalized to the ICU department of Tunisian University hospital of Sousse, between December 1, 2009 and March 31, 2016, with a positive influenza A/H1N1/09 reverse transcriptase polymerase chain reaction (RT-PCR) from a nasopharyngeal specimen were included, were included.

RESULTS

40 cases were admitted to intensive care units. During the reporting period, 22 deaths in intensive care units (55%) were reported, the median age was 53 years (IQR 37-61), 24 (61%) were male, The median scores SAPS II and SOFA were respectively 29 (IQR 23-36) and 6 (IQR 3-10), 27% had chronic obstructive pulmonary disease (COPD), 33.3% diabetic and no patients were vaccinated against influenza A. The cause of admission was in 72.5% of the cases was hypoxemic pneumonae. By using a logistic regression, we found after adjustment to age, that acute respiratory distress syndrome (ARDS) (OR = 27; 95%CI: 3.62-203.78) was the only factor significantly associated with severe outcomes of the cases.

CONCLUSION

Patients in the first post pandemic season were significantly older and more frequently had underlying medical conditions. Multivariate analysis showed that older male patients with chronic lung disease were at increased risk for a severe clinical outcome.

Epidemiology of influenza virus types and subtypes in South Africa, 2009-2012

Patient age and co-infections, but not disease severity, were associated with virus type and subtype.

To determine clinical and epidemiologic differences between influenza caused by different virus types and subtypes, we identified patients and tested specimens. Patients were children and adults hospitalized with confirmed influenza and severe acute respiratory illness (SARI) identified through active, prospective, hospital-based surveillance from 2009–2012 in South Africa. Respiratory specimens were tested, typed, and subtyped for influenza virus by PCR. Of 16,005 SARI patients tested, 1,239 (8%) were positive for influenza virus. Patient age and co-infections varied according to virus type and subtype, but disease severity did not. Case-patients with influenza B were more likely than patients with influenza A to be HIV infected. A higher proportion of case-patients infected during the first wave of the 2009 influenza pandemic were 5–24 years of age (19%) than were patients infected during the second wave (9%). Although clinical differences exist, treatment recommendations do not differ according to subtype; prevention through vaccination is recommended.

Impact of H1N1 on socially disadvantaged populations: summary of a systematic review

BACKGROUND

Previous reviews found that the H1N1 pandemic was associated with a large proportion of hospitalizations, severe illness, workplace absenteeism, and high costs. However, the burden among socially disadvantaged groups of the population is unclear. This is a summary of a previously published systematic review commissioned by the World Health Organization on the burden of H1N1 pandemic (influenza A/Mexico/2009 (H1N1)) among socially disadvantaged populations.

METHODS

MEDLINE and EMBASE were searched to identify studies reporting hospitalization, severe illness, and mortality attributable to the 2009 H1N1 pandemic among socially disadvantaged populations, including ethnic minorities and low-income or lower-middle-income economy countries (LIC/LMIC). SAS and Review Manager were used to conduct random effects meta-analysis.

RESULTS

Forty-eight cohort studies and 14 companion reports including 44 777 patients were included after screening 787 citations and 164 full-text articles. Twelve of the included studies provided data on LIC/LMIC, including one study from Guatemala, two from Morocco, one from Pakistan, and eight from India, plus four companion reports. The rest provided data on ethnic minorities living in high-income economy countries (HIC). Significantly more hospitalizations were observed among ethnic minorities versus nonethnic minorities in two North American studies [1313 patients, odds ratio (OR) 2·26 (95% confidence interval: 1·53-3·32)]. Among hospitalized patients in HIC, statistically significant differences in intensive care unit admissions (n = 8 studies, 15 352 patients, OR 0·84 [0·69-1·02]) and deaths (n = 6 studies, 14 757 patients, OR 0·85 [95% CI: 0·73-1·01]) were not observed.

CONCLUSION

We found significantly more hospitalizations among ethnic minorities versus nonethnic minorities in North America, yet no differences in intensive care unit admissions or deaths among H1N1-infected hospitalized patients were observed in North America and Australia. Our results suggest a similar burden of H1N1 between ethnic minorities and nonethnic minorities living in HIC.

Comparison of clinical presentation and laboratory values at admission between PCR-confirmed influenza A H1N1 infection and influenza-like disease, South-East Austria

PURPOSE

Reliable and rapid diagnosis of influenza A H1N1 is essential to initiate the appropriate antiviral therapy and preventive measures. As PCR assays are time-consuming and rapid antigen tests have a limited sensitivity, official influenza case definitions are used in many clinical settings. These, however, are based exclusively on clinical criteria and have only a moderate potential to differentiate between influenza and other febrile diseases. Only limited data on the differences in clinical and laboratory parameters between influenza and non-influenza febrile diseases are available to date.

METHODS

This was a retrospective case-negative control series that was conducted in Styria, southeast Austria. We analyzed the differences in clinical presentation and laboratory admission parameters between patients with PCR-confirmed H1N1 influenza infection (n = 199) and those with influenza-like disease and negative influenza PCR results (ILD group; n = 252).

RESULTS

In the multivariable analysis lower C-reactive protein (CRP) level, lower white blood cell (WBC) count, fever, wheezing, cough, and the absence of nausea or sudden onset remained significant predictors of H1N1 influenza in adult patients (n = 263). Lower CRP level, lower WBC count, and cough remained significant predictors in pediatric patients (<16 years; n = 188).

CONCLUSION

Lower CRP level, lower WBC count, and cough were significant predictors of H1N1 in both the adult and pediatric patient group. These data may help to develop an improved case definition for suspected H1N1 infection which combines clinical findings and easily available laboratory parameters.

Changes in severity of influenza A(H1N1)pdm09 infection from pandemic to first postpandemic season, Germany

We studied risk factors for a severe clinical outcome in hospitalized patients with laboratory-confirmed influenza A(H1N1)pdm09 infection at the University Hospital Heidelberg in the pandemic and first postpandemic seasons. We identified 102 patients in 2009–10 and 76 in 2010–11. The proportion of severely diseased patients dramatically increased from 14% in 2009–10 to 46% in 2010–11 as did the mortality rate (5%–12%). Patients in the first postpandemic season were significantly older (38 vs. 18 years) and more frequently had underlying medical conditions (75% vs. 51%). Overall, 50 patients (28%) had a severe clinical outcome, resulting in 14 deaths. Multivariate analysis showed that older male patients with chronic lung disease were at increased risk for a severe clinical outcome. In summary, the proportion of patients with severe disease and fatal cases increased in the postpandemic season. Therefore, patients with suspected infections should be promptly identified and receive early treatment.

The first, second and third wave of pandemic influenza A (H1N1)pdm09 in North Denmark Region 2009-2011: a population-based study of hospitalizations

Background and objectives

Denmark experienced three waves of the new pandemic influenza A (H1N1)pdm09 from July 2009 to February 2011. The aim of the study was to describe the epidemiology and clinical characteristics of hospitalized patients in a defined population of North Denmark Region with a mixed urban and rural community of 579 000 inhabitants.

Methods

Review of medical records of all hospitalized patients with confirmed influenza A from July 2009 to February 2011.

Results

Two hundred and seventy‐three patients were admitted to hospital. The age‐related population incidences of hospitalization were as follows: 0–14 years: 111/100 000, 15–64 years: 39/100 000, and ≥65 years: 17/100 000. During the first wave (July 2009–August 2009), three patients were admitted – none received treatment in intensive care units (ICUs), during the second wave (October 2009–January 2010), 158 patients were admitted – nine received treatment in ICUs, and during the third wave (December 2010–February 2011), 112 patients were admitted – 25 received treatment in ICUs. Fourteen patients (5%) died within 30 days of diagnosis (median 55 years; range 14–76 years) and additional seven patients (2·6%) died within 365 days (median 25 years; range 1–86 years).

Conclusions

Patients hospitalized with pandemic influenza A (H1N1)pdm09 were predominantly children and younger adults, and only a few patients were >65 years. The third wave was the most severe taking the number and percentage of patients admitted to ICUs and 30‐day mortality into consideration. We observed that the incidence of hospitalizations as well as clinical severity among younger adults did not decline from the second to the third wave.

Impact of H1N1 on socially disadvantaged populations: systematic review

BACKGROUND

The burden of H1N1 among socially disadvantaged populations is unclear. We aimed to synthesize hospitalization, severe illness, and mortality data associated with pandemic A/H1N1/2009 among socially disadvantaged populations.

METHODS/PRINCIPAL FINDINGS

Studies were identified through searching MEDLINE, EMBASE, scanning reference lists, and contacting experts. Studies reporting hospitalization, severe illness, and mortality attributable to laboratory-confirmed 2009 H1N1 pandemic among socially disadvantaged populations (e.g., ethnic minorities, low-income or lower-middle-income economy countries [LIC/LMIC]) were included. Two independent reviewers conducted screening, data abstraction, and quality appraisal (Newcastle Ottawa Scale). Random effects meta-analysis was conducted using SAS and Review Manager.

CONCLUSIONS/SIGNIFICANCE

Sixty-two studies including 44,777 patients were included after screening 787 citations and 164 full-text articles. The prevalence of hospitalization for H1N1 ranged from 17-87% in high-income economy countries (HIC) and 11-45% in LIC/LMIC. Of those hospitalized, the prevalence of intensive care unit (ICU) admission and mortality was 6-76% and 1-25% in HIC; and 30% and 8-15%, in LIC/LMIC, respectively. There were significantly more hospitalizations among ethnic minorities versus non-ethnic minorities in two studies conducted in North America (1,313 patients, OR 2.26 [95% CI: 1.53-3.32]). There were no differences in ICU admissions (n = 8 studies, 15,352 patients, OR 0.84 [0.69-1.02]) or deaths (n = 6 studies, 14,757 patients, OR 0.85 [95% CI: 0.73-1.01]) among hospitalized patients in HIC. Sub-group analysis indicated that the meta-analysis results were not likely affected by confounding. Overall, the prevalence of hospitalization, severe illness, and mortality due to H1N1 was high for ethnic minorities in HIC and individuals from LIC/LMIC. However, our results suggest that there were little differences in the proportion of hospitalization, severe illness, and mortality between ethnic minorities and non-ethnic minorities living in HIC.