Intended for healthcare professionals


Implications of prognostic pessimism in patients with chronic obstructive pulmonary disease (COPD) or asthma admitted to intensive care in the UK within the COPD and asthma outcome study (CAOS): multicentre observational cohort study

BMJ 2007; 335 doi: (Published 29 November 2007) Cite this as: BMJ 2007;335:1132
  1. Martin J Wildman, consultant chest physician1,
  2. Colin Sanderson, reader in health services research2,
  3. Jayne Groves, research nurse3,
  4. Barnaby C Reeves, reader in epidemiology2,
  5. Jon Ayres, professor4,
  6. David Harrison, senior statistician5,
  7. Duncan Young, consultant intensivist6,
  8. Kathy Rowan, director5
  1. 1Northern General Hospital, Sheffield
  2. 2London School of Hygiene and Tropical Medicine, London
  3. 3Birmingham Heartlands Hospital, Birmingham
  4. 4Department of Occupational and Environmental Medicine, Liberty Safe Work Research Centre, Aberdeen
  5. 5Intensive Care National Audit and Research Centre, London
  6. 6Adult Intensive Care Unit, John Radcliffe Hospital, Oxford
  1. Correspondence to: M Wildman martin.wildman{at}
  • Accepted 10 September 2007


Objective To determine whether clinicians' prognoses in patients with severe acute exacerbations of obstructive lung disease admitted to intensive care match observed outcomes in terms of survival.

Design Prospective cohort study.

Setting 92 intensive care units and three respiratory high dependency units in the United Kingdom.

Participants 832 patients aged 45 years and older with breathlessness, respiratory failure, or change in mental status because of an exacerbation of COPD, asthma, or a combination of the two.

Main outcome measures Outcome predicted by clinicians. Observed survival at 180 days.

Results 517 patients (62%) survived to 180 days. Clinicians' prognoses were pessimistic, with a mean predicted survival of 49% at 180 days. For the fifth of patients with the poorest prognosis according to the clinician, the predicted survival rate was 10% and the actual rate was 40%. Information from a database covering 74% of intensive care units in the UK suggested no material difference between units that participated and those that did not. Patients recruited were similar to those not recruited in the same units.

Conclusions Because decisions on whether to admit patients with COPD or asthma to intensive care for intubation depend on clinicians' prognoses, some patients who might otherwise survive are probably being denied admission because of unwarranted prognostic pessimism.


  • We thank all the units that participated in the CAOS study and the intensive care national audit and research centre for its invaluable role in recruiting units and data linkage. We thank Jan Van Der Meulen for advice on the data analysis.

  • Contributors: MJW, CS, KR, JA, BCR, and DY were involved in the original design of the study. MJW coordinated the study, carried out the initial data analysis, and drafted the paper. JG helped to collect the data. CS carried out additional analyses and drafted the final paper. KR and DH helped recruit the units and facilitated data linkage with the case mix programme. MJW is guarantor.

  • Funding: MJW was funded by an MRC Health Services Research Fellowship. JG was funded by an NHS research and development grant.

    Competing interests: None declared.

  • Ethical approval: Multicentre research ethics committees.

    Provenance and peer review: Not commissioned; externally peer reviewed.

  • Accepted 10 September 2007
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