Bruce Taylor

Risk factors for hospitalisation and poor outcome with pandemic A/H1N1 influenza: United Kingdom first wave (May–September 2009)

Background During the first wave of pandemic H1N1 influenza in 2009, most cases outside North America occurred in the UK. The clinical characteristics of UK patients hospitalised with pandemic H1N1 infection and risk factors for severe outcome are described. Methods A case note-based investigation was performed of patients admitted with confirmed pandemic H1N1 infection. Results From 27 April to 30 September 2009, 631 cases from 55 hospitals were investigated. 13% were admitted to a high dependency or intensive care unit and 5% died; 36% were aged <16 years and 5% were aged ≥65 years. Non-white and pregnant patients were over-represented. 45% of patients had at least one underlying condition, mainly asthma, and 13% received antiviral drugs before admission. Of 349 with documented chest x-rays on admission, 29% had evidence of pneumonia, but bacterial co-infection was uncommon. Multivariate analyses showed that physician-recorded obesity on admission and pulmonary conditions other than asthma or chronic obstructive pulmonary disease (COPD) were associated with a severe outcome, as were radiologically-confirmed pneumonia and a raised C-reactive protein (CRP) level (≥100 mg/l). 59% of all in-hospital deaths occurred in previously healthy people. Conclusions Pandemic H1N1 infection causes disease requiring hospitalisation of previously fit individuals as well as those with underlying conditions. An abnormal chest x-ray or a raised CRP level, especially in patients who are recorded as obese or who have pulmonary conditions other than asthma or COPD, indicate a potentially serious outcome. These findings support the use of pandemic vaccine in pregnant women, children <5 years of age and those with chronic lung disease.

Predictors of clinical outcome in a national hospitalised cohort across both waves of the influenza A/H1N1 pandemic 2009–2010 in the UK

Background Although generally mild, the 2009–2010 influenza A/H1N1 pandemic caused two major surges in hospital admissions in the UK. The characteristics of patients admitted during successive waves are described. Methods Data were systematically obtained on 1520 patients admitted to 75 UK hospitals between May 2009 and January 2010. Multivariable analyses identified factors predictive of severe outcome. Results Patients aged 5–54 years were over-represented compared with winter seasonal admissions for acute respiratory infection, as were non-white ethnic groups (first wave only). In the second wave patients were less likely to be school age than in the first wave, but their condition was more likely to be severe on presentation to hospital and they were more likely to have delayed admission. Overall, 45% had comorbid conditions, 16.5% required high dependency (level 2) or critical (level 3) care and 5.3% died. As in 1918–1919, the likelihood of severe outcome by age followed a W-shaped distribution. Pre-admission antiviral drug use decreased from 13.3% to 10% between the first and second waves (p=0.048), while antibiotic prescribing increased from 13.6% to 21.6% (p<0.001). Independent predictors of severe outcome were age 55–64 years, chronic lung disease (non-asthma, non-chronic obstructive pulmonary disease), neurological disease, recorded obesity, delayed admission (≥5 days after illness onset), pneumonia, C-reactive protein ≥100 mg/litre, and the need for supplemental oxygen or intravenous fluid replacement on admission. Conclusions There were demographic, ethnic and clinical differences between patients admitted with pandemic H1N1 infection and those hospitalised during seasonal influenza activity. Despite national policies favouring use of antiviral drugs, few patients received these before admission and many were given antibiotics.

Nosocomial Pandemic (H1N1) 2009, United Kingdom, 2009-2010.

To determine clinical characteristics of patients hospitalized in the United Kingdom with pandemic (H1N1) 2009, we studied 1,520 patients in 75 National Health Service hospitals. We characterized patients who acquired influenza nosocomially during the pandemic (H1N1) 2009 outbreak. Of 30 patients, 12 (80%) of 15 adults and 14 (93%) of 15 children had serious underlying illnesses. Only 12 (57%) of 21 patients who received antiviral therapy did so within 48 hours after symptom onset, but 53% needed escalated care or mechanical ventilation; 8 (27%) of 30 died. Despite national guidelines and standardized infection control procedures, nosocomial transmission remains a problem when influenza is prevalent. Health care workers should be routinely offered influenza vaccine, and vaccination should be prioritized for all patients at high risk. Staff should remain alert to the possibility of influenza in patients with complex clinical problems and be ready to institute antiviral therapy while awaiting diagnosis during influenza outbreaks.

Clinical and laboratory features distinguishing pandemic H1N1 influenza-related pneumonia from interpandemic community-acquired pneumonia in adults

Background Early identification of patients with H1N1 influenza-related pneumonia is desirable for the early instigation of antiviral agents. A study was undertaken to investigate whether adults admitted to hospital with H1N1 influenza-related pneumonia could be distinguished clinically from patients with non-H1N1 community-acquired pneumonia (CAP). Methods Between May 2009 and January 2010, clinical and epidemiological data of patients with confirmed H1N1 influenza infection admitted to 75 hospitals in the UK were collected by the Influenza Clinical Information Network (FLU-CIN). Adults with H1N1 influenza-related pneumonia were identified and compared with a prospective study cohort of adults with CAP hospitalised between September 2008 and June 2010, excluding those admitted during the period of the pandemic. Results Of 1046 adults with confirmed H1N1 influenza infection in the FLU-CIN cohort, 254 (25%) had H1N1 influenza-related pneumonia on admission to hospital. In-hospital mortality of these patients was 11.4% compared with 14.0% in patients with inter-pandemic CAP (n=648). A multivariate logistic regression model was generated by assigning one point for each of five clinical criteria: age ≤65 years, mental orientation, temperature ≥38°C, leucocyte count ≤12×109/l and bilateral radiographic consolidation. A score of 4 or 5 predicted H1N1 influenza-related pneumonia with a positive likelihood ratio of 9.0. A score of 0 or 1 had a positive likelihood ratio of 75.7 for excluding it. Conclusion There are substantial clinical differences between H1N1 influenza-related pneumonia and inter-pandemic CAP. A model based on five simple clinical criteria enables the early identification of adults admitted with H1N1 influenza-related pneumonia.

Guidance on the use of respiratory and facial protection equipment

Summary Infectious micro-organisms may be transmitted by a variety of routes, and some may be spread by more than one route. Respiratory and facial protection is required for those organisms that are usually transmitted via the droplet/airborne route, or when airborne particles have been artificially created, such as during ‘aerosol-generating procedures’. A range of personal protective equipment that provides different degrees of facial and respiratory protection is available. It is apparent from the recent experiences with severe acute respiratory syndrome and pandemic (H1N1) 2009 influenza that healthcare workers may have difficulty in choosing the correct type of facial and respiratory protection in any given clinical situation. To address this issue, the Scientific Development Committee of the Healthcare Infection Society established a short-life working group to develop guidance. The guidance is based upon a review of the literature, which is published separately, and expert consensus.

Differences between asthmatics and nonasthmatics hospitalised with influenza A infection

Asthmatics hospitalised because of influenza A infection are less likely to require intensive care or die compared with nonasthmatics. The reasons for this are unknown. We performed a retrospective analysis of data on 1520 patients admitted to 75 UK hospitals with confirmed influenza A/H1N1 2009 infection. A multivariable model was used to investigate reasons for the association between asthma and severe outcomes (intensive care unit support or death). Asthmatics were less likely than nonasthmatics to have severe outcome (11.2% versus 19.8%, unadjusted OR 0.51, 95% CI 0.36–0.72) despite a greater proportion requiring oxygen on admission (36.4% versus 26%, unadjusted OR 1.63) and similar rates of pneumonia (17.1% versus 16.6%, unadjusted OR 1.04). The results of multivariable logistic regression suggest the association of asthma with outcome (adjusted OR 0.62, 95% CI 0.36–1.05; p=0.075) are explained by pre-admission inhaled corticosteroid use (adjusted OR 0.34, 95% CI 0.18–0.66) and earlier admission (≤4 days from symptom onset) (adjusted OR 0.60, 95% CI 0.38–0.94). In asthmatics, systemic corticosteroids were associated with a decreased likelihood of severe outcomes (adjusted OR 0.36, 95% CI 0.18–0.72). Corticosteroid use and earlier hospital admission explained the association of asthma with less severe outcomes in hospitalised patients.

Comparison of CATs, CURB-65 and PMEWS as triage tools in pandemic influenza admissions to UK hospitals: case control analysis using retrospective data.

Triage tools have an important role in pandemics to identify those most likely to benefit from higher levels of care. We compared Community Assessment Tools (CATs), the CURB-65 score, and the Pandemic Medical Early Warning Score (PMEWS); to predict higher levels of care (high dependency - Level 2 or intensive care - Level 3) and/or death in patients at or shortly after admission to hospital with A/H1N1 2009 pandemic influenza. This was a case-control analysis using retrospectively collected data from the FLU-CIN cohort (1040 adults, 480 children) with PCR-confirmed A/H1N1 2009 influenza. Area under receiver operator curves (AUROC), sensitivity, specificity, positive predictive values and negative predictive values were calculated. CATs best predicted Level 2/3 admissions in both adults [AUROC (95% CI): CATs 0.77 (0.73, 0.80); CURB-65 0.68 (0.64, 0.72); PMEWS 0.68 (0.64, 0.73), p<0.001] and children [AUROC: CATs 0.74 (0.68, 0.80); CURB-65 0.52 (0.46, 0.59); PMEWS 0.69 (0.62, 0.75), p<0.001]. CURB-65 and CATs were similar in predicting death in adults with both performing better than PMEWS; and CATs best predicted death in children. CATs were the best predictor of Level 2/3 care and/or death for both adults and children. CATs are potentially useful triage tools for predicting need for higher levels of care and/or mortality in patients of all ages.

Critical Care Contingency Planning: Phased Responses and Triaging Framework

As most of our readers will be aware from previous publications and from the special articles contained in this edition, a lot of work has gone into highlighting the implications of an influenza pandemic for critical care services and trying to work out how to make the best use of the resources that may be available. The latest Department of Health Document ‘Pandemic influenza: surge capacity and prioritisation in health services – provisional UK guidance’ (available on the DH website) has made an encouraging start in providing official recognition of the problems likely to be encountered as a result of limited bed capacity, and also supports the concept that triaging decisions cannot be left to secondary care (and particularly critical care specialists) alone. Regrettably, however, even if its recommendations for patient selection are fully followed and the number of inappropriate referrals to critical care is reduced significantly, there is still a strong probability that during the peak of a pandemic the number of patients who are likely to benefit from critical care will still significantly exceed bed capacity – even if this is maximally expanded. In the original working of the Critical Care Contingency Planning Group a draft document on Phased Responses and Triaging was produced as a starter to addressing these difficulties. Further work on this was then put on-hold pending the production of official ethical guidance and other documentation to address these problems. However, now that these have been finalised and we still face potential dilemmas about how ICUs will be able to cope, feedback from critical care network discussions has persuaded us that it may be useful to circulate a revised version of this document, updated to include more recent recommendations, in the hope that this may be of help in assisting local planning. In particular, the document addresses two concepts that were initially felt to be inappropriate or unacceptable, but which now may be considered reasonable/realistic. These are the possibility of using some method of lottery selection if there are several appropriate referrals but insufficient bed numbers, and the fact that at some point there may be a requirement to accept temporary closure of intensive care to further referrals if no beds are available. It is hoped that consensus support for the principles of this document may help to produce reassurance for staff (with the support of local PCTs and Trust Management) that if potentially preventable deaths occur in such circumstances they will not be vulnerable to litigation or professional criticism when no other treatment options were available.

Effect of ethnicity on care pathway and outcomes in patients hospitalized with influenza A(H1N1)pdm09 in the UK

SUMMARY Data were extracted from the case records of UK patients admitted with laboratory-confirmed influenza A(H1N1)pdm09. White and non-White patients were characterized by age, sex, socioeconomic status, pandemic wave and indicators of pre-morbid health status. Logistic regression examined differences by ethnicity in patient characteristics, care pathway and clinical outcomes; multivariable models controlled for potential confounders. Whites (n = 630) and non-Whites (n = 510) differed by age, socioeconomic status, pandemic wave of admission, pregnancy, recorded obesity, previous and current smoking, and presence of chronic obstructive pulmonary disease. After adjustment for a priori confounders non-Whites were less likely to have received pre-admission antibiotics [adjusted odds ratio (aOR) 0·43, 95% confidence interval (CI) 0·28–0·68, P < 0·001) but more likely to receive antiviral drugs as in-patients (aOR 1·53, 95% CI 1·08–2·18, P = 0·018). However, there were no significant differences by ethnicity in delayed admission, severity at presentation for admission, or likelihood of severe outcome.

An Evaluation of Community Assessment Tools (CATs) in Predicting Use of Clinical Interventions and Severe Outcomes during the A(H1N1)pdm09 Pandemic

During severe influenza pandemics healthcare demand can exceed clinical capacity to provide normal standards of care. Community Assessment Tools (CATs) could provide a framework for triage decisions for hospital referral and admission. CATs have been developed based on evidence that supports the recognition of severe influenza and pneumonia in the community (including resource limited settings) for adults, children and infants, and serious feverish illness in children. CATs use six objective criteria and one subjective criterion, any one or more of which should prompt urgent referral and admission to hospital. A retrospective evaluation of the ability of CATs to predict use of hospital-based interventions and patient outcomes in a pandemic was made using the first recorded routine clinical assessment on or shortly after admission from 1520 unselected patients (800 female, 480 children <16 years) admitted with PCR confirmed A(H1N1)pdm09 infection (the FLU-CIN cohort). Outcome measures included: any use of supplemental oxygen; mechanical ventilation; intravenous antibiotics; length of stay; intensive or high dependency care; death; and “severe outcome” (combined: use of intensive or high dependency care or death during admission). Unadjusted and multivariable analyses were conducted for children (age <16 years) and adults. Each CATs criterion independently identified both use of clinical interventions that would in normal circumstances only be provided in hospital and patient outcome measures. “Peripheral oxygen saturation ≤92% breathing air, or being on oxygen” performed well in predicting use of resources and outcomes for both adults and children; supporting routine measurement of peripheral oxygen saturation when assessing severity of disease. In multivariable analyses the single subjective criterion in CATs “other cause for clinical concern” independently predicted death in children and in adults predicted length of stay, mechanical ventilation and “severe outcome”; supporting the role of clinical acumen as an important independent predictor of serious illness.