From the authors

We welcome the contribution from K. Challen and co-workers concerning their pandemic medical early warning score (PMEWS) compared with CURB-65 (confusion, urea >7 mmol·L^-1, respiratory rate ≥30·min^-1, low blood pressure, and aged ≥65 yrs) and CRB-65 (confusion, respiratory rate ≥30·min^-1, low blood pressure, and aged ≥65 yrs) as measures to determine hospital and intensive care unit admission for patients with lower respiratory tract infection (LRTI) and community-acquired pneumonia (CAP), but would urge caution before deciding which test to use in either CAP or pandemic influenza.

CURB-65 and CRB-65 have been developed for the assessment, at hospital admission, of patients with CAP and have now been validated in widely different populations 1. Draft UK guidelines for the clinical management of pandemic influenza (www.dh.gov.uk/PublicationsAndStatistics/Publications/PublicationsPolicyAndGuidance/PublicationsPolicyAndGuidanceArticle/fs/en?CONTENT_ID = 4121753&chk = ZXKxus) have used these scores as examples of how a severity scoring tool might be used in the light of this evidence base. However, neither the CURB scores nor PMEWS have actually been tested in patients with seasonal, let alone pandemic, influenza where their operational characteristics may be different.

Other important issues are that CURB scores have been assessed in large patient populations compared with the 195 LRTI and 99 CAP patients described by K. Challen and co-workers. Important information is omitted by K. Challen and co-workers including: the definition of LRTI used; the proportion of LRTI patients admitted to hospital; and how many patients had missing variables. Without scrutiny of such information, we would not agree with these authors that they have shown that PMEWS can provide a more accurate assessment of need for hospital admission.

Importantly, K. Challen and co-workers fail to mention that PMEWS is a graded score for each parameter, rather than the categorical scores used in CURB, making PMEWS inherently more complex to use, especially outside the hospital. In addition, CRB-65 can be calculated without any laboratory or oximetric results.

The medical early warning score has the potential advantages of not being disease specific, and familiarity of use in some UK hospitals at least, for the assessment of patients already admitted to hospital. However, we know of no studies reporting its use as a tool for the hospital admission decision.

More detailed and prospective assessment will be required before pandemic medical early warning scores can be recommended in preference to a score validated in a number of populations and now adopted in a number of international community-acquired pneumonia guidelines (www.brit-thoracic.org/guidelines) 2–4.