ORIGINAL ARTICLES
Clinical features of acute febrile thrombocytopaenia among patients attending primary care clinics
Tong Seng Fah MMed(FamMed UKM), Noorazah Abdul Aziz MMed (FamMed UKM), Chin Gek Liew FRCP(Edin),
Khairani Omar MMed(FamMed UKM)
Department of Family Medicine, Universiti Kebangsaan Malaysia (UKM)
Introduction: Identifying clinical features that differentiate acute febrile thrombocytopaenia from acute febrile illness without thrombocytopaenia can help primary care physician to decide whether to order a full blood count (FBC). This is important because thrombocytopaenia in viral fever may signify more serious underlying aetiology like dengue infection.
Objective: The aim of this study was to compare the clinical features of acute febrile patients with thrombocytopaenia and acute febrile patients without thrombocytopaenia.
Methodology: This was a clinic-based cross-sectional study from May to November 2003. Consecutive patients presenting with undifferentiated fever of less than two weeks were selected from the Primary Care Centre of Hospital Universiti Kebangsaan Malaysia and Batu 9 Cheras Health Clinic. Clinical features of these patients were recorded and FBC examination was done for all patients. Thrombocytopaenia was defined as platelet count <150X109/L. The odds ratio of thrombocytopaenia for each presenting symptoms was calculated.
Result: Seventy-three patients participated in this study. Among them, 45.2% had thrombocytopaenia. Myalgia and headache were common among all patients. However, nausea and vomiting occurred significantly more often among patients with thrombocytopaenia than in patients with normal platelet count (OR 2.2, 95% CI 1.1-4.5).
Conclusion: Acute non-specific febrile patients presenting with symptoms of nausea and vomiting may have higher risk of thrombocytopaenia and should be seriously considered for FBC.
Key words: viral infection, dengue, clinical features, thrombocytopaenia.
See also See Commentary by Esha Das Gupta.
INTRODUCTION
Dengue infection is the most common arthropod-borne infection in the tropics where it carries significant morbidity, mortality and immense economic burden to the countries affected.1 The incidence of dengue infection is on the rise in Malaysia.2 Early diagnosis of dengue infection is important in order to minimise mortality.3 Diagnosis of dengue infection is supported if there is thrombocytopaenia, the presence of which often signify more serious type of dengue infection.4-6 All these point to the importance of detecting thrombocytopaenia in suspected dengue patients.
It is difficult to differentiate dengue infection from other viral infections due to the overlap in the symptoms. 7-12 To make the distinction, one may decide to order full blood count (FBC) for all febrile patients. This practice is often impractical due to the large number of febrile patients in the outpatient clinic. Thus, clinical features that suggest the presence of thrombocytopaenia help primary care physician to decide whether full blood count is necessary. The objective of this study is to identify clinical features that differentiate between febrile patients with and without thrombocytopaenia.
METHODS
This was a cross-sectional study conducted at two primary care clinics (Primary Care Centre of Hospital Universiti Kebangsaan Malaysia and Batu 9 Cheras Health Clinic) from May 2003 to November 2003. Consecutive febrile patients who fulfilled study criteria were invited to participate in the study. The inclusion criteria were age ≥12 years with a history of fever for less than 2 weeks. Fever was defined as oral temperature >37.5oC. Patients were excluded if localised source of infection can be identified, e.g. urinary tract infection. Illnesses with pathognomonic clinical features e.g. varicella infection, measles, rubella, scarlet fever and dengue haemorrhagic fever. Consents were taken from all eligible patients before enrolment. Their clinical features were recorded using standard data collection sheet and FBC examination was done for all patients. The investigators were blinded to the FBC result until all clinical features were recorded. In this study, patients with thrombocytopaenia (defined as platelet count <150X109/L) were managed as dengue infection until the availability of their dengue IgG and IgM status.13 Patients with normal platelet count were called back on day 5 of illness for a repeat clinical assessment and FBC examination in order not to miss any dengue infection.