Guidelines on SARS should be refined

Evaluation of WHO criteria for identifying patients with severe acute respiratory syndrome out of hospital: prospective observational study BMJ Volume 326, pp 1354-8

Current World Health Organisation (WHO) guidelines for diagnosing suspected SARS may not be sufficiently sensitive in assessing patients before admission to hospital, suggest researchers from Hong Kong in this week’s BMJ.

The study took place in a newly opened SARS screening clinic at the Prince of Wales Hospital in Hong Kong from 12-31 March 2003, and involved 556 hospital staff, patients, and relatives who had had contact with someone with SARS. Of the 556 people, 141 were admitted to hospital, and 97 had confirmed SARS.

The WHO guidelines currently emphasise respiratory tract symptoms such as cough, shortness of breath, and breathing difficulty. But the team found that these symptoms did not feature strongly in the early stages of the illness. Instead, symptoms such as fever, chills, loss of appetite, vomiting, and diarrhoea, were significantly more common among the 97 patients.

In screening patients for SARS, these symptoms may be better indications than the symptoms listed in the WHO guidelines, which were based on patients who were already in hospital, say the authors.

The WHO guidelines also emphasise temperature readings of 38C or more, but over half of cases did not have such levels of fever during the pre-hospital screening phase, they add.

“The WHO criteria should be refined to include routine daily follow up, documentation of non-respiratory systemic symptoms, and daily chest radiography until patients have passed at least 48 hours without symptoms,” they conclude.

In a second study at the same hospital, researchers found abnormal blood cell counts in patients with SARS. For instance, of 157 patients assessed, 98% developed lymphopenia (a decrease in numbers of lymphocytes in the blood), and 55% developed thrombocytopenia (a decrease in the number of blood platelets).

Studies of the effect of SARS on various body systems are crucial to the understanding of this disease, say the authors, and further studies to evaluate the mechanisms of these changes are needed.

Contact: Emma Dickinson, edickinson@bmj.com