Assessing changes in knowledge, attitude and practices on dengue diagnosis and management among primary care physicians after the largest dengue epidemic in Singapore

Dengue, one of the major global burdens, is estimated to affect at least 50 million people annually [1]. Dengue haemorrhagic fever (DHF) and Dengue shock syndrome (DSS) are severe clinical manifestations for dengue infection in both adult and children. Identifying the disease early and predicting the possible outcomes effectively is a leading concern for Public Health specialists managing the disease [2]

Dengue fever (DF) is endemic in the tropical and sub-tropical regions, including Singapore [2]. Dengue was first reported in Singapore in the early 1960 [3]. Since 1969, with the implementation of vector control and surveillance, public health education and law enforcement, there has been a general decline in disease incidence, until in 1990 when dengue began to surge again [4]. Since then, Singapore has faced several dengue epidemic. Spikes have been recorded in 2005 and 2007 with 14,209 and 8826 cases respectively [5]. The largest dengue epidemic was experienced in the year 2013 with 22,170 reported dengue cases with eight deaths [6]. In Singapore, the occurrence of DF and DHF are influenced by several factors such as lowered herd immunity and virus transmission outside the home by Aedes mosquitoes, which potentially resulted in the resurgence of dengue incidences among adult population [7].

In 1997, the World Health Organization introduced dengue management guidelines for diagnosis, treatment, prevention and control [8]. A revised edition was released in 2009 with updated information for better clinical management, vector management and laboratory diagnosis [9]. Dengue virus infection may be asymptomatic or symptomatic that may lead to unpredictable severe outcomes such as death. In the three largest outbreak clusters in Singapore, it was revealed that 73.2% of residents with recent infection were asymptomatic [5]. Hence, early detection of these dengue cases and monitoring of disease severity are important parts of dengue management to reduce dengue transmission and burden.

Moreover, to avoid over-hospitalization during an epidemic, it is important to have a system not only for early detection but also effective outpatient monitoring. Since the development of Dengue Duo POCT kit [10], there were many clinical validation studies performed such as the SD Dengue Duo POCT kit (Standard Diagnostics, Inc., Gyeonggi-do, Korea) with sensitivities and specificities ranging from 75.5–92.9% and 88.8–100% respectively using frozen serum or plasma samples [11‐14]. This commercially available assay uses whole blood to obtain dengue positivity result within 30 min of patient presentation. In 2013, SD Dengue Duo POCT kit was also validated in Singapore with sensitivity and specificity of 93.9% and 92.0% respectively [15], with significant reduction (from estimated four hours to an hour) in the time required from patient presentation to appropriate clinical management in a tertiary hospital. This kit, which includes both dengue NS1 antigen and dengue IgM & IgG antibody detection, is likely to enhance early diagnosis of dengue and reduce dengue burden at the primary healthcare settings. A good understanding of the changes in KAP of the dengue management among the PCPs will be important to reduce dengue burden. Even though there were two cross-sectional KAP studies focusing on the dengue management of PCPs in Southern Vietnam [16] and Southern Taiwan [17], there is still a lack of understanding on the changes of KAP after a large dengue epidemic.

Therefore the aims of this study were to (1) Examine changes in primary care physicians knowledge, attitude and practices, in particular on the usage of dengue diagnostic tests and related clinical practices; (2) Enquire about their experience on using the POCT kit; (3) Gather recommendations for improved service delivery in patient diagnostics and clinical care management to facilitate reduction in dengue burden.

Primary care physicians (PCPs) play very important role in early diagnosis and notification of dengue cases to reduce dengue transmission and burden [1]. The right knowledge, attitude and practices on dengue management among PCPs are critical for dengue control and public education [16, 17]. Since 2011, there have been advances in providing better dengue management for suspected dengue patients in Singapore. Gan et al. in 2014 reported the high performance of point-of-care diagnostic Dengue duo test in detecting dengue infection in a clinic setting in Singapore [15]. Leo et al. in 2013 reported the validation of the new World Health Organization guideline in Singapore. The study reported that dengue patients without any of the seven warning signs as stated in the guideline may be managed as outpatients, while referral of patients who presented with any of these warning signs may lead to over-hospitalization [19].

Over the years between year 2011 and 2014, the proportion of PCPs who always diagnosed dengue using diagnostic test had increased by about two folds, and those who never used diagnostic test to confirm dengue fell by about three folds (Table 3). Compared to private PCPs, all of PCPs from polyclinics had higher preference to perform diagnostic test for patients with suspected dengue in 2014. Although Dengue duo POCT kit was only introduced in 2013, more than one third of PCPs had preference to use the POCT kit based on the survey in 2014. On further assessment, Dengue duo POCT test was independently associated with frequent use of diagnostic test after adjusting for age, gender, level of professional qualification and place of practice. This highlights the impact of POCT in increasing the usage of diagnostic test in primary healthcare setting to confirm dengue for early management of dengue cases as well as for dengue control via notification to Ministry of Health.

The PCPs emphasized that availability of the POCT kit at the place of practice, accuracy of the test, rapidness of results and cost-effectiveness favored its use. The PCPs’ preference to receive more information on diagnostic tests was through postal mails or website with video demonstration on its usage. They were also concerns over the use of this new POCT kit. These concerns were the lack of quality control and increased workload in the clinic, which were also highlighted in another study by Pai et al. in 2012 [20]. Our findings suggested that further development of more accurate and user-friendly test kits, as well as having highly accessible training platforms for front line care providers are likely to increase the use of dengue diagnostic test in both public and private primary healthcare settings to enhance patient management.

After the large dengue epidemic, most PCPs felt that dengue case management had improved. This was likely due to the availability of better dengue diagnostic tests, greater awareness of the disease and clearer clinical guidelines. Compared to the 2011 survey, the survey in 2014 showed PCPs referred patients to hospital with a lower platelet cut-off of ≤50,000/mm³, which is clinically more relevant for close monitoring. Similar platelet cut-off was also reported by Thaver et al. in 2011 amongst the Pakistanis PCPs [21]. We also found that our Singapore PCPs became more confident, and committed to managing the dengue patients as outpatients, with closer monitoring, where possible. This was reflected in the significant reduction in patient referrals to hospital and the increased number of clinical reviews at the primary healthcare setting.

Carrasco et al. in 2011 highlighted that managing dengue cases in hospital incurred 10 times more cost than ambulatory care in Singapore ($600 vs. $60 per day, respectively) [22]. Lee et al. also reported in 2013 that after the implementation of the new admission criteria including dengue outcome calculator which utilizes simple and readily available clinical information, the proportion of dengue cases who were being managed as inpatients fell from 91.9% in 2006 to 53.9% in 2008 with saving of US$ 1.4 million in year 2008 [23]. Similar cost savings to both patients and the government is likely possible with a significant reduction in dengue referrals to hospital with the increasing usage of POCT based on the findings in this study.

We were limited by the fact that there were significant differences in gender, age groups and the highest qualifications attained among the PCPs surveyed in 2011 and 2014. As such, we cannot completely exclude the impact of these demographic differences. However, regardless of the demographic differences, the knowledge level on clinical management remained high, suggesting that the impact on PCPs’ attitude and practices of dengue diagnosis should be relatively small. We were also limited by the survey method in collecting more explorative qualitative data. However, open-ended survey questions provided additional in depth information about physicians attitudes and experiences on dengue clinical management and diagnosis. The case management data that was collected was based on three case management scenarios (Additional file 3) with the aim to understand common practices amongst primary care physicians. These data will not be able to capture the optimal case management of a suspected dengue case but only the current preferred case management of a suspected dengue case. In fact, Dengue has many overlapping features with other febrile illnesses. It would be ideal to apply simple, cheap and easy to use diagnostic test at primary care sites for optimal case management. In addition, this study involved only PCPs who were practicing during the 2013 epidemic due to their valid practicing licenses and clinic addresses. As such, this study is not able to conclude if PCPs who were not practicing during 2013 epidemic had the same awareness as those PCPs who were practicing. Last but not least, the low response rate may not provide a complete understanding of the changes in KAP on dengue management after a large dengue epidemic. However, a comparison on the demographics of PCPs between this study and another national study published in 2014 [24], the proportion of PCPs surveyed reflects the general PCPs reasonably well, although there are more older PCPs than younger PCPs (<45 years old) in both 2011 and 2014 surveys (Table 1).

After the largest dengue outbreak in 2013, knowledge on clinical management of dengue remain high, but not higher between year 2011 and 2014. However, there were significant improvements in the diagnosis of dengue, particularly on the importance of using a diagnostic kit such as the dengue Duo POCT kit. There were also significant increase in awareness and practices of the best practices of dengue clinical management between 2011 and 2014. In order to improve acceptance & usage of the POCT kit to facilitate early diagnosis of dengue, it may be worth emphasizing the importance of continuous medical education via web-based video trainings and postal information, the sharing of formal evaluations of the diagnostic tests in local settings through seminars or dialogue sessions, as well as the support of the local government in providing subsidy for the usage of POCT kit in the primary healthcare settings.