A urinary screening program is recommended as a fundamental element for decreasing the incidence of CKD [9]. However, the concern regarding cost-effectiveness was mentioned in studies of European and North American authors [10–12]. The retrospective study on cost-effectiveness conducted in children with hematuria and proteinuria, and published in Pediatrics 2010, supports the change in the AAP guidelines [10]. Nevertheless, according to the authors, this analysis was limited by several factors. In Asia, Japan was the first country to conduct a national screening program for children aged 6 to 14 in 1973 [6, 13, 14]. After that, other countries, like Taiwan, Korea, Malaysia and Singapore, have established screening programs. In these different studies, the collected urine was tested by a dipstick [4–7, 13, 15]. In Vietnam, the health care system is hardly making progress; children are not regularly followed by a doctor every 2 years like in the United States or in Europe. Moreover, doctors are not available at all health centers, particularly pediatricians. Can Gio is a typical example where the children do not maximally benefit from medical care. Therefore, implementing urinary screening programs should be considered in remote locations like Can Gio.
In Vietnam, to our knowledge, this is the first report about urinary screening in a large population of asymptomatic children. Dipsticks were used with the aims of searching proteinuria and/or proteinuria with hematuria for the detection of a nephropathy, and of searching proteinuria and/or leukocyturia or nitrituria in order to find partially treated pyelonephritis because in remote areas of Vietnam, there is no pediatrician and nearly all children presenting with fever are treated with antibiotics.
Vietnam is a developing country where little is known about the prevalence of urinary abnormalities in asymptomatic children. The prevalence of abnormalities has varied among different authors in different regions all over the world. Our prevalence in the first screening (22.3%) and the overall prevalence (5.5%) were higher than those reported in Nepalese, Lebanese and Malaysian studies [16–18]. In contrast, a higher prevalence has been reported in Nigeria by Akor et al.[19]. This variation may be due to different populations, different socioeconomic statuses and the prevalence of renal diseases within these populations.
While there were no differences between age groups, significant differences in the number of positive urinalyses across communes were found. Depending on the component, a positive dipstick can be the result of exercise, vaginal contamination, wrong sampling method, exposure of reagent strip to air, or consuming vitamin C or foods with high vitamin C content. The same brand of reagent strip, preserved in the same conditions, was used to test all children. Our results may therefore be explained by the special context of Can Gio. In particular, Thanh An and Ly Nhon are the two poorest communes in Can Gio, where the hygiene conditions are not good, fresh water is inadequate and the people have a low socioeconomic status. There is therefore a possibility of contamination and wrong sampling method that must be considered. This can also be evidenced more clearly by the prevalence of each separate component; the prevalence of nitrituria, leucocyturia and the percentage of false positives were high. As one can see, a supply of fresh water and hygiene education for parents and teachers in Can Gio are essential. In addition, a similar study in a population living in an urban area of HCMC is necessary for comparison and a subjective evaluation.
In our study, girls had a positive dipstick more frequently than boys. A similar result has been reported in other studies [13, 15, 17, 19] whereas no gender difference was found in the Bakr et al.’s study [20]. This higher positive proportion included a predominance of nitrituria and leucocyturia. There was a significant difference for these two parameters between girls and boys in our results. Girls have short urethra, which facilitates ascending bacterial infection. Moreover, sampling is more difficult in girls than in boys.
Isolated nitrituria and isolated leucocyturia were the most two common abnormalities in our study. This is different from the findings of African authors [19]. As Vietnam is a tropical country, our result suggests an important prevalence of urinary tract infection (UTI) among these children. The exact prevalence of UTI is unknown for many reasons. Firstly, the signs are not specific. Secondly, there is the possibility of using the wrong technique for collecting urine in young children. Thirdly, antibiotics are often proposed to a febrile child and the urinary tract infection may be suppressed as a consequence. Two meta-analyses have shown a sensitivity of 0.88 for the presence of either leucocyte esterase or nitrite [21, 22]. In contrast, the urine culture of 102 samples at CH2 in HCMC revealed no UTI because the samples had <105 colony forming units per mL (CFU/mL) of one single type bacteria growing. All these cases with asymptomatic bacteriuria should not be treated with antibiotics nor with prophylactic antibiotics [23]. In Can Gio, children presenting with fever are commonly treated directly with antibiotics by physicians, without microbiological evidence, due to the lack of a paediatrician and the lack of a microbiology laboratory. Consequently, setting up a microbiology laboratory in Can Gio was deemed necessary in order to confirm diagnoses and to improve the treatment of UTI in children. This is why we have introduced a new protocol at the Can Gio District Hospital requesting a dipstick for each child presenting with fever and without any evidence of an infection focus; if leukocyturia and/or nitrituria is found, a urinary culture should be performed to search for bacteria. To follow this protocol, we have implemented a microbiology laboratory at the Can Gio District Hospital, with the help and the support of microbiologists from the Children’s Hospital 2. With the emergence of resistant bacteria worldwide, treatment with antibiotics based on nitrituria and/or leucocyturia before establishing the diagnosis by urine culture is not recommended, especially in a country with many infectious diseases like Vietnam.
The epidemiological study of bacteriuria in infants of a Swedish cohort reported positivity in 2.5% of boys and 0.9% of girls, and no major malformations were found after urography [23]. Westwood et al. concluded that there was no evidence to support the clinical effectiveness of routine investigation of children with confirmed UTI [24]. In our study concerning asymptomatic children, the five subjects with a positive urine culture for bacteria were investigated with a renal ultrasound; four of them were normal. The urography was therefore arguably not necessary. However, current recommendations for evaluation of UTI include performing an ultrasound and a voiding cystourethrogram after the first UTI. Searching for other modifiable host factors, such as voiding dysfunction or constipation, is crucial following the documentation of a UTI [25, 26]. Hence, the appearance of any symptoms suggestive of a UTI in children should lead to a complete assessment, especially because vesicoureteral reflux is proved to be associated with recurrent infections [27, 28]. Of course, vesicoureteral reflux is only interesting as a cause of UTIs in the youngest children or in those with recurrent pyelonephritis. Otherwise factors related to bladder function (including constipation) are much more important. This is why information campaigns were conducted in Can Gio for parents and educators on voiding disorders in children, pointing the importance of hygiene and hydration.
Hematuria and/or proteinuria are the aim of most urinary screenings among asymptomatic children because the finding of both hematuria and proteinuria may suggest the presence of an underlying renal disease. In our study, there were no cases of combined hematuria and proteinuria, although this number varies from 0.03% to 2.3% in other countries [5, 7, 13, 18]. The number of children with isolated proteinuria was 0.1% at the second screening. Our prevalence was equivalent to data of Tokyo, Lebanon and Egypt, which were 0.8%, 0.1% and 1.2%, respectively [13, 17, 20]. We first used morning urine samples to exclude orthostatic proteinuria as a cause of false positive proteinuria. A very high urine pH may also be a cause of false positive proteinuria. This may explain why we had 7/10 cases with a negative protein at second dipstick. Renal biopsy and rigourous follow-up have allowed early intervention in selected cases, as evidenced by Japanese and Taiwanese populations [5, 13]. In our cross-sectional study, one limitation was that we could not identify the underlying pathology of the two cases with isolated proteinuria because parents refused to continue the study.
The 0.1% prevalence of isolated hematuria in our study is lower than the 1.5% from previous studies [17, 19] and higher than prevalence of Nepal, Malaysia Japan and Korea [13, 15, 16, 18]. Only persistent hematuria reveals the presence of kidney diseases, of which the main causes are lupus nephritis and IgA nephropathy. Two children with IH in our study were directed to health stations for follow-up. Of the seven cases with positive hematuria on the first dipstick, five were negative on the second one. This may be due to contaminated urine specimens.
The number of false positives in our study was high for all four main components. Aside from the special conditions of Can Gio that we previously described, one element that must be considered is the population in our study’s young age, making it difficult to obtain mid-stream urine. According to Yanagihara et al., in order to validate a screening program, attention should be paid to quality controls of the screening method, such as the selection of reagent strips, and the participants should be instructed to strictly adhere to the sampling method [6]. It is very difficult to instruct young children and parents, particularly in places with economical, health care and educational hardships. The disadvantage in the sample’s transportation is also an issue to take into consideration.
