Health expert says up to half of dengue cases misdiagnosed, proposes new dengue severity classifications
Confusion brought about by variations in dengue severity often lead to misdiagnosis in as high as 50 percent of dengue cases.
This was the finding from a study done by the Dengue Control (DENCO) Working Group of the Department of Health conducted in January 25-May 25, 2009.
Biomedical expert Dr. Efren Dimaano, who heads San Lazaro Hospital's Clinical Division, says health workers get confused due to the very broad definition of dengue adopted by the World Health Organization (WHO) and the Department of Health (DOH).
Because the definition is too broad, Dimaano said, clinicians do not have confidence in treating mild dengue patients as outpatients since “they will feel guilty” if they do not admit a patient who is suspected to have dengue.
Misdiagnosis often cost patients money because they are admitted in hospitals even for mild dengue. Such cases could be monitored as outpatients instead, Dimaano said, and managed at home through simple medication and oral rehydration using hydrite tablets.
But a much graver problem than the unnecessary hospital expense is the possible death of misdiagnosed dengue patients.
Mild dengue patients admitted in hospitals are given intravenous (IV) fluid, which remains the “foundation” of dengue management in the country.
But he says, the infusion of IV fluids should be judiciously observed in such cases since mild dengue patients recover more quickly and have lower hematocrit levels than those with severe cases.
Unmonitored IV therapy could lead to fluid overload or pulmonary congestion, which could kill a patient. Dimaano says this fluid overload or pulmonary congestion is recognized as the most common cause of death in dengue cases.
Usually, he said, those with high hematocrit levels are given 5-7 liters of IV fluid per day. For mild dengue cases, 2 to 3 liters of IV fluids per day should be enough for maintenance, according to Dimaano.
The severity of dengue cases can be better appreciated and understood by the public if they are classified in more “user-friendly, not too laboratory-based” terms, according to biomedical expert Dr. Efren Dimaano, head of San Lazaro Hospital's Clinical Division.
This, aside from the adaptation of the classifications of dengue, will help clinicians with no medical training to manage dengue especially in poor areas without trained doctors.
He also suggested that a uniform age and weight guideline for IV fluid therapy should be distributed in hospitals all over the country.
Dimaano presented his recommendations Wednesday in a symposium on dengue organized by Novartis, a pharmaceutical company conducting clinical research to develop a vaccine against the mosquito-borne disease.
He said the recommended classifications are more specific, making it easier to understand than the current classifications for dengue severity, which are too broad and confusing for a non-doctor or trained medical expert.
The study recommended the following new dengue severity classifications:
1) Dengue without warning signs – when a person has travelled to a dengue-prone area, proved positive of dengue fever via laboratory examination and exhibits two of the following:
- Aches and Pains
- Anorexia or nausea
- Has any one of the warning signs (refer to dengue with warning signs)
2) Dengue (proven positive) with warning signs:
- Abdominal pain or tenderness
- Persistent vomiting
- Clinical fluid accumulation
- Mucosal bleeding
- Lethargy; restlessness
- Liver enlargement of more than 2 cm.
- Laboratory test showing an increase in hematocrit levels concurrent with rapid decrease in platelet count
3) Severe Dengue:
- Severe plasma leakage leading to shock and fluid accumulation, resulting in respiratory distress
- Severe bleeding as evaluated by a clinician
- Liver enzymes AST or SGOT and ALT or SGPT count is more than or equal to 100
- Circulatory and nervous system is affected, and dengue patient has impaired consciousness
- Heart and other organs are affected, these will be seen in laboratory examinations
In the absence of laboratory equipment, the Tourniquet Test (TT) is recommended by the World Health Organization (WHO) to detect dengue. To conduct a TT, a blood pressure cuff is applied and inflated on a person's upper arm for five minutes. When at least 20 small red or purple spots called petechiae, which are caused by minor hemorrhage, appear on the skin beyond the cuff, one can be declared positive for dengue.
The current WHO and DOH case definition of dengue follow a history of fever for 2-7 days and the patient has two of the following signs: myalgia or arthragia, retro-orbital pain, hemorrhage, nausea or vomiting, leucopenia and testing positive from laboratory or TT. The severity of dengue is classified as:
- Dengue Fever (mild) – no plasma leakage
- Dengue Hemorrhagic Fever (DHF) – plasma leakage, hemorrhagic tendency, has a platelet count of less than 100,000
- Dengue Shock Syndrome DHF 3 – signs of circulator failure
- Dengue Shock Syndrome DHF 4 – profound shock
|Table : Dengue Fatality Rates
||Confirmed Fatality Rate
|Source: National Center for Disease Prevention and Control, DOH
When the new dengue severity classification was tested at the San Lazaro hospital and regional hospitals in Regions 3 and 4, dengue management became easier for clinicians, said Dimaano.
He said that the three hospitals recorded only a 2% misdiagnosis rate — a very small number compared to other hospitals around the country that recorded more than 50% misdiagnosis rate when tests were done from January 25 to May 25, 2009.
The new dengue classifications, he said, gave confidence to clinicians to rule mild dengue patients as outpatients.
He said it would be very helpful to adapt the recommended classifications in health centers without trained doctors or nurses in the Philippines.
Dimaano said there were too many guidelines for dengue management. Because clinicians are bombarded with guidelines from different health and medical institutions, they become confused and have low confidence in deciding on the kind of treatment to give dengue patients, he said. An example of this is the practice of unnecessary blood transfusions, he said.
Clinicians are torn between guidelines to follow so they succumb to the pressure of the patients' relatives urging them to perform the said blood therapy.
Dimaano said dengue experts around the world will meet in Malaysia in November hopefully to consolidate an updated guideline with the new classifications.
Status of Dengue in the Philippines
Dr. Yolanda Oliveros, Director IV of the DOH, said that the number of dengue cases as of August 1, 2009, was 16,317. This was down 37% from the same period last year, she said. So far, the fatality rate has been only one percent.
Oliveros said the number of dengue cases first peaked in the Philippines in 1998 with more than 35,000 cases during a global dengue outbreak. But, she said, the most number of cases in the country– 55,135–was recorded in 2007.
Oliveros said that dengue fatality rate was highest in 1997 even though the number of dengue cases for that year was comparatively low.