THURSDAY, June 19 (HealthDayNews) -- The existing World Health Organization guidelines for diagnosing severe acute respiratory syndrome (SARS) may not be adequate.

While current WHO guidelines emphasize respiratory symptoms such as shortness of breath, coughing, and difficulty breathing, a team of researchers reporting in the June 21 issue of the British Medical Journal feels that emphasis may be misplaced. Symptoms at the early stages of the illness in the patients they studied were more likely to include fever, chills, loss of appetite, vomiting, and diarrhea.

A proposed revision of the guidelines is currently being considered for publication.

These non-respiratory symptoms occurred when the patients were highly infectious but not yet hospitalized. The WHO guidelines were based on symptoms evident in patients already in the hospital and therefore slightly later in their phase of the disease.

"The new guidelines [on initial testing] appear much more useful in community screening contexts than current WHO guidelines," Dr. Timothy Rainer wrote in an e-mail to HealthDay.

"The new guidelines may require further validation before most clinicians accept them, but they provide the first primary-care evidence base to guide clinical decision making," added Rainer, lead author of the study and an emergency department physician at the Prince of Wales Hospital and an associate professor at the Chinese University of Hong Kong in China.

The WHO did not respond to a request for comment.

The researchers conducted their study at a new SARS screening clinic in the emergency department of the Prince of Wales Hospital in Hong Kong between March 12 and 31. The screening clinic was set up on March 12 in response to a SARS outbreak that affected 15 doctors, 15 nurses, 17 medical students, and five other staffers associated with one ward at the hospital.

In all, Rainer and his colleagues looked at 556 hospital staffers, patients, and relatives who had had contact with someone with SARS. Of the 556 people, 141 were admitted to the hospital and 97 had confirmed SARS.

The overall accuracy of the WHO guidelines for identifying suspected SARS cases was 83 percent, and they accurately predicted who did not have the disease 86 percent of the time. These guidelines have a sensitivity of 26 percent and a specificity of 96 percent. Sensitivity refers to the ability to detect true positive cases while specificity refers to the ability to weed out false-positives.

The revised guidelines, according to Rainer, have a sensitivity of almost 99 percent "in the context of a known outbreak," compared to the WHO's 26 percent.

According to the study authors, applying the WHO criteria would have meant that doctors would have missed 72 cases, or 74 percent of the total.

The WHO's recommendation that only fevers over 100.4 degrees Fahrenheit be considered will also mean many missed cases, the researchers said. "For the new guidelines we would also like to emphasize daily follow-up and daily chest X-ray until there is a 48-hour period free of symptoms or pyrexia [fever]," Rainer added.

"Fever, defined as a symptom, should be included [in new guidelines], along with other systemic symptoms such as chills, malaise, rigors, and myalgia [muscle pain]," Rainer wrote. "Respiratory symptoms have poor discriminatory value in the early phase of detection."

Along with the previously mentioned symptoms, patients with confirmed SARS in this study also exhibited a significantly higher heart rate, lower mean systolic blood pressure, and higher mean temperature than those who did not have the disease.

The new guidelines should be widely publicized, the study authors say. "All primary care staff -- emergency physicians, general practitioners, minor clinics, general and specialist out-patient departments need to be aware," Rainer wrote. "Governments and immigration bodies also need to realize that taking temperature readings at airports and other border crossings may be an important political exercise but is probably of little clinical usefulness in terms of detecting SARS cases."

A second study conducted at the same hospital in Hong Kong found that patients with SARS also had abnormal blood cell counts. Of 157 patients assessed, 98 percent developed lymphopenia, or a decrease in the numbers of lymphocytes in the blood and 55 percent developed thrombocytopenia, a decrease in the number of blood platelets. All of the patients had been diagnosed with SARS between March 11 and March 29.

More information

Visit the U.S. Centers for Disease Control and Prevention for more information on all aspects of SARS, or the World Health Organization for information on its guidelines and recommendations.