Test characteristics of the urine Gram stain in infants <or= 60 days of age with fever

Urinary tract infections in children: Testing a novel, noninvasive, point-of-care diagnostic marker

OBJECTIVES

Urinary neutrophil gelatinase-associated lipocalin (uNGAL) appears highly accurate to identify urinary tract infections (UTIs) when obtained via catheterization. Our primary aim was to determine the agreement in uNGAL levels between paired catheter and bag urine specimens. Our secondary aim was to compare the diagnostic test characteristics of quantitative uNGAL, dipstick uNGAL (a potential point-of-care test), and urinalysis (UA).

METHODS

This was a prospective study of febrile children < 24 months evaluated for UTIs. We evaluated quantitative uNGAL at a previously identified threshold of 39.1 ng/mL, dipstick uNGAL at its built-in threshold of >50 ng/mL, and UA at standard thresholds for leukocyte esterase (LE). A positive urine culture was defined as >100,000 CFUs/mL of a pathogen.

RESULTS

A total of 211 patients were included (10% with positive urine cultures); 116 had paired catheterized and bagged samples. The agreement between catheterized and bagged samples at a quantitative uNGAL cutoff of ≥39.1 ng/mL was 0.76 (95% confidence interval [CI] = 0.67 to 0.83) and 0.77 (95% CI = 0.68 to 0.84) at a uNGAL dipstick threshold of >50 ng/mL. The area under the receiver operating characteristic curve for uNGAL from a catheterized sample was 0.96 (95% CI = 0.89 to 1.00) compared to 0.93 (95% CI = 0.87 to -0.99) from a bagged sample. The sensitivities of catheterized sample quantitative and dipstick uNGAL (90.5%) were higher than UA at a LE threshold of ≥1+ (57.1%). Bagged-sample uNGAL had lower quantitative and dipstick specificities (both 73.8%) than from catheterized samples (94.3% and 95.3% respectively), similar to UA.

CONCLUSIONS

uNGAL from bagged and catheterized samples showed insufficient agreement to be used interchangeably. The low specificity of uNGAL from bagged samples suggests that sampling technique affects uNGAL levels.

Diagnostic value of biomarkers for paediatric urinary tract infections in primary care: systematic review and meta-analysis

Background

Accurate diagnosis of urinary tract infection is essential as children left untreated may suffer permanent renal injury.

Aim

To compare the diagnostic values of biomarkers or clinical prediction rules for urinary tract infections in children presenting to ambulatory care.

Design and setting

Systematic review and meta-analysis of ambulatory care studies.

Methods

Medline, Embase, WOS, CINAHL, Cochrane library, HTA and DARE were searched until 21 May 2021. We included diagnostic studies on urine or blood biomarkers for cystitis or pyelonephritis in children below 18 years of age. We calculated sensitivity, specificity and likelihood ratios. Data were pooled using a bivariate random effects model and a Hierarchical Summary Receiver Operating Characteristic analysis.

Results

Seventy-five moderate to high quality studies were included in this review and 54 articles in the meta-analyses. The area under the receiver-operating-characteristics curve to diagnose cystitis was 0.75 (95%CI 0.62 to 0.83, n = 9) for C-reactive protein, 0.71 (95% CI 0.62 to 0.80, n = 4) for procalcitonin, 0.93 (95% CI 0.91 to 0.96, n = 22) for the dipstick test (nitrite or leukocyte esterase ≥trace), 0.94 (95% CI 0.58 to 0.98, n = 9) for urine white blood cells and 0.98 (95% CI 0.92 to 0.99, n = 12) for Gram-stained bacteria. For pyelonephritis, C-reactive protein < 20 mg/l had LR- of 0.10 (95%CI 0.04–0.30) to 0.22 (95%CI 0.09–0.54) in children with signs suggestive of urinary tract infection.

Conclusions

Clinical prediction rules including the dipstick test biomarkers can support family physicians while awaiting urine culture results. CRP and PCT have low accuracy for cystitis, but might be useful for pyelonephritis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12875-021-01530-9.

Diagnosis and Management of UTI in Febrile Infants Age 0-2 Months: Applicability of the AAP Guideline

Urinary tract infections (UTIs) are the most common bacterial infection in young infants. The American Academy of Pediatrics' (AAP) clinical practice guideline for UTIs focuses on febrile children age 2-24 months, with no guideline for infants <2 months of age, an age group commonly encountered by pediatric hospitalists. In this review, we assess the applicability of the AAP UTI Guideline's action statements for previously healthy, febrile infants <2 months of age. We also discuss additional considerations in this age group, including concurrent bacteremia and routine testing for meningitis.

Using urine nitrite sticks to test for urinary tract infection in children aged < 2 years: a meta-analysis

BACKGROUND

This study aimed to determine whether nitrite sticks are as sensitive at detecting urinary tract infection (UTI) in children <2 years as they are in older children.

METHODS

I reanalysed data on using nitrite sticks to detect UTIs for children aged either < 2 or 2-18 years. For sensitivity, evidence of a UTI was defined as level 1 when a single uropathogen grew ≥ 10⁵ colony forming units/ml (cfu/ml) in two urine samples, level 2 when just one sample was cultured or a threshold of < 10⁵ cfu/ml was used, and level 3 if mixed growths or Staphylococcus albus was considered to be positive. For specificity, children were defined as uninfected if they had 1 sterile urine culture. I also reanalysed our previously published data by age.

RESULTS

The sensitivity was lower for children aged < 2 years (11 studies, 1321 subjects) than for older children (9 studies, 295 subjects), whether the level-1 values or all the studies were analysed (Fisher's exact test, p < 0.0001 for both). The level-1 sensitivities were 0.23 in the infants and 0.81 among older children (odds ratio = 0.07, 95% confidence interval 0.03-0.18). The specificity was very high in infants (10 studies, 1783 cases) and older children (7 studies, 5952 cases), at 0.990 and 0.996.

CONCLUSIONS

Nitrite sticks only have a 23% sensitivity in children aged < 2 years, so cannot reliably rule out UTIs. A positive nitrite stick test is about 99% likely to indicate a UTI in children of any age.

The Diagnosis of Urinary Tract infection in Young children (DUTY): a diagnostic prospective observational study to derive and validate a clinical algorithm for the diagnosis of urinary tract infection in children presenting to primary care with an acute illness

BACKGROUND

It is not clear which young children presenting acutely unwell to primary care should be investigated for urinary tract infection (UTI) and whether or not dipstick testing should be used to inform antibiotic treatment.

OBJECTIVES

To develop algorithms to accurately identify pre-school children in whom urine should be obtained; assess whether or not dipstick urinalysis provides additional diagnostic information; and model algorithm cost-effectiveness.

DESIGN

Multicentre, prospective diagnostic cohort study.

SETTING AND PARTICIPANTS

Children < 5 years old presenting to primary care with an acute illness and/or new urinary symptoms.

METHODS

One hundred and seven clinical characteristics (index tests) were recorded from the child's past medical history, symptoms, physical examination signs and urine dipstick test. Prior to dipstick results clinician opinion of UTI likelihood ('clinical diagnosis') and urine sampling and treatment intentions ('clinical judgement') were recorded. All index tests were measured blind to the reference standard, defined as a pure or predominant uropathogen cultured at ≥ 10(5) colony-forming units (CFU)/ml in a single research laboratory. Urine was collected by clean catch (preferred) or nappy pad. Index tests were sequentially evaluated in two groups, stratified by urine collection method: parent-reported symptoms with clinician-reported signs, and urine dipstick results. Diagnostic accuracy was quantified using area under receiver operating characteristic curve (AUROC) with 95% confidence interval (CI) and bootstrap-validated AUROC, and compared with the 'clinician diagnosis' AUROC. Decision-analytic models were used to identify optimal urine sampling strategy compared with 'clinical judgement'.

RESULTS

A total of 7163 children were recruited, of whom 50% were female and 49% were < 2 years old. Culture results were available for 5017 (70%); 2740 children provided clean-catch samples, 94% of whom were ≥ 2 years old, with 2.2% meeting the UTI definition. Among these, 'clinical diagnosis' correctly identified 46.6% of positive cultures, with 94.7% specificity and an AUROC of 0.77 (95% CI 0.71 to 0.83). Four symptoms, three signs and three dipstick results were independently associated with UTI with an AUROC (95% CI; bootstrap-validated AUROC) of 0.89 (0.85 to 0.95; validated 0.88) for symptoms and signs, increasing to 0.93 (0.90 to 0.97; validated 0.90) with dipstick results. Nappy pad samples were provided from the other 2277 children, of whom 82% were < 2 years old and 1.3% met the UTI definition. 'Clinical diagnosis' correctly identified 13.3% positive cultures, with 98.5% specificity and an AUROC of 0.63 (95% CI 0.53 to 0.72). Four symptoms and two dipstick results were independently associated with UTI, with an AUROC of 0.81 (0.72 to 0.90; validated 0.78) for symptoms, increasing to 0.87 (0.80 to 0.94; validated 0.82) with the dipstick findings. A high specificity threshold for the clean-catch model was more accurate and less costly than, and as effective as, clinical judgement. The additional diagnostic utility of dipstick testing was offset by its costs. The cost-effectiveness of the nappy pad model was not clear-cut.

CONCLUSIONS

Clinicians should prioritise the use of clean-catch sampling as symptoms and signs can cost-effectively improve the identification of UTI in young children where clean catch is possible. Dipstick testing can improve targeting of antibiotic treatment, but at a higher cost than waiting for a laboratory result. Future research is needed to distinguish pathogens from contaminants, assess the impact of the clean-catch algorithm on patient outcomes, and the cost-effectiveness of presumptive versus dipstick versus laboratory-guided antibiotic treatment.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Urinary Neutrophil Gelatinase-Associated Lipocalin for the Diagnosis of Urinary Tract Infections

OBJECTIVES

To determine the accuracy of the novel biomarker urinary neutrophil gelatinase-associated lipocalin (uNGAL) to diagnose urinary tract infections (UTIs) in febrile infants and young children.

METHODS

Prospective cross-sectional study of febrile infants <3 months ( ≥ 38.0°C) and children 3 to 24 months (≥ 39.0°C) evaluated for UTIs. uNGAL levels, urinalysis, Gram-stain and culture were obtained. UTI was defined by colony counts.

RESULTS

Of 260 patients, 35 (13.5%) had UTIs. Median uNGAL levels were 215.1 ng/mL (interquartile range: 100.3-917.8) and 4.4 ng/mL (interquartile range: 1.6-11.8) in the groups diagnosed with and without UTIs, respectively. The area under the receiver-operating characteristic curve for uNGAL was 0.978 (95% confidence interval [CI]: 0.948-1.000). At a threshold uNGAL level of 39.1 ng/mL, sensitivity was 97.1% (95% CI: 83.4-99.9) and specificity was 95.6% (95% CI: 91.7-97.7). uNGAL had higher sensitivity than the combination of leukocyte esterase (in trace or greater amounts) or nitrite (+) (97.1%, 95% CI: 83.4-99.9 vs 74.3%, 95% CI: 56.4-86.9), with similar specificity (95.6%, 95% CI: 91.7-97.7 vs 97.3%, 95% CI: 94.0-98.9). uNGAL had higher sensitivity than Gram-stain (97.1%, 95% CI: 83.4-99.9 vs 74.3%, 95%: CI: 56.4-86.9), with similar specificity (95.6%, 95% CI: 91.7-97.7 vs 100.0%, 95% CI: 97.9-100.0).

CONCLUSIONS

uNGAL has substantial accuracy to identify those with and without UTIs in infants and young children. Further studies will need to confirm our findings and determine if uNGAL is a more cost-effective test than standard screening tests.

Using a urine dipstick to identify a positive urine culture in young febrile infants is as effective as in older patients

AIM

There is limited evidence about the diagnostic value of urine dipsticks in young febrile infants. The aim of this study was to determine whether urine dipsticks would identify positive urine cultures in febrile infants of less than 90 days of age.

METHODS

This study was a subanalysis of a prospective multicentre study developed in 19 Spanish paediatric emergency departments belonging to the Spanish Paediatric Emergency Research Network. It focused on febrile infants of less than 90 days of age admitted between October 2011 and September 2013. A positive urine culture was defined as the growth of ≥ 50,000 cfu/mL of a single pathogen collected by a sterile method.

RESULTS

We included 3401 patients, and 176 (12.8%) female patients and 473 (23.3%) males had a positive urine culture. The leucocyte esterase test showed a mean sensitivity of 82.1% and a mean specificity of 92.4%, with a greater mean negative predictive value for females than males (97.8 versus 94.1%) and a greater mean positive predictive value for males than females (79.4% versus 58%).

CONCLUSION

The leucocyte esterase test showed the same accuracy in young febrile infants as previously reported findings for older children. It predicted positive urine cultures and also revealed important gender differences.

Diagnosis and management of urinary tract infection and vesicoureteral reflux in the neonate

Urinary tract infection (UTI) is the most common bacterial infection in febrile newborns, particularly those born prematurely and with a low birth weight. Vesicoureteral reflux (VUR) predisposes to UTI and renal scarring. Half of neonates with UTI may have only low-grade fever or no fever. Jaundice in the absence of any other symptoms or signs may be the only clinical manifestation of UTI in neonates. The urinalysis may be negative in a significant number of neonates with UTI. Newborns with UTI have a high incidence of congenital anomalies of kidney and urinary tract anomalies, and hence should undergo renal imaging.

Dipstick screening for urinary tract infection in febrile infants

OBJECTIVE

This study compares the performance of urine dipstick alone with urine microscopy and with both tests combined as a screen for urinary tract infection (UTI) in febrile infants aged 1 to 90 days.

METHODS

We queried the Intermountain Healthcare data warehouse to identify febrile infants with urine dipstick, microscopy, and culture performed between 2004 and 2011. UTI was defined as >50 000 colony-forming units per milliliter of a urinary pathogen. We compared the performance of urine dipstick with unstained microscopy or both tests combined ("combined urinalysis") to identify UTI in infants aged 1 to 90 days.

RESULTS

Of 13 030 febrile infants identified, 6394 (49%) had all tests performed and were included in the analysis. Of these, 770 (12%) had UTI. Urine culture results were positive within 24 hours in 83% of UTIs. The negative predictive value (NPV) was >98% for all tests. The combined urinalysis NPV was 99.2% (95% confidence interval: 99.1%-99.3%) and was significantly greater than the dipstick NPV of 98.7% (98.6%-98.8%). The dipstick positive predictive value was significantly greater than combined urinalysis (66.8% [66.2%-67.4%] vs 51.2% [50.6%-51.8%]). These data suggest 8 febrile infants would be predicted to have a false-positive combined urinalysis for every 1 infant with UTI initially missed by dipstick screening.

CONCLUSIONS

Urine dipstick testing compares favorably with both microscopy and combined urinalysis in febrile infants aged 1 to 90 days. The urine dipstick test may be an adequate stand-alone screen for UTI in febrile infants while awaiting urine culture results.

Absolute and relative accuracy of rapid urine tests for urinary tract infection in children: a meta-analysis

Rapid urine tests, such as microscopy, for bacteria and white cells, and dipsticks, for leucocyte esterase and nitrites, are often used in children that are unwell to guide early diagnosis and treatment of urinary tract infection. We aimed to establish whether these tests were sufficiently sensitive to avoid urine culture in children with negative results and to compare the accuracy of dipsticks with microscopy. Medline, Embase, and reference lists were searched. Studies were included if urine culture results were compared with rapid tests in children. Data were analysed to obtain absolute and relative accuracy estimates. Data from 95 studies in 95 703 children were analysed. Summary estimates for sensitivity and specificity for microscopy for Gram-stained bacteria were 91% (95% CI 80-96) and 96% (92-98), for unstained bacteria were 88% (75-94) and 92% (84-96), for urine white cells were 74% (67-80) and 86% (82-90), for leucocyte esterase or nitrite positive dipstick were 88% (82-91) and 79% (69-87), and for nitrite-only positive dipstick were 49% (41-57) and 98% (96-99). Microscopy for bacteria with Gram stain had higher accuracy than other laboratory tests with relative diagnostic odds ratio compared with bacteria without Gram stain of 8.7 (95% CI 1.8-41.1), white cells of 14.5 (4.7-44.4), and nitrite of 22.0 (0.7-746.3). Microscopy for white cells should not be used for the diagnosis of urinary tract infection because its accuracy is no better than that of dipstick, laboratory facilities are needed, and results are delayed. Rapid tests are negative in around 10% of children with a urinary tract infection and cannot replace urine culture. If resources allow, microscopy with Gram stain should be the single rapid test used.

Diagnostic performance of urine dipstick testing in children with suspected UTI: a systematic review of relationship with age and comparison with microscopy

BACKGROUND

Prompt diagnosis of urinary tract infection (UTI) in children is needed to initiate treatment but is difficult to establish without urine testing, and reliance on culture leads to delay. Urine dipsticks are often used as an alternative to microscopy, although the diagnostic performance of dipsticks at different ages has not been established systematically.

METHOD

Studies comparing urine dipstick testing in infants versus older children and urine dipstick versus microscopy were systematically searched and reviewed. Meta-analysis of available studies was conducted.

RESULTS

Six studies addressed these questions. The results of meta-analysis showed that the performance of urine dipstick testing was significantly less in the younger children when compared with older children (p < 0.01). Positive likelihood ratio (LR) of both nitrite and leucocyte positive 38.54 [95% confidence interval (CI) 22.49-65.31], negative LR for both negative 0.13 (95% CI 0.07-0.25) are reasonably good, and those for young infants are less reliable [positive LR 7.62 (95% CI 0.95-51.85) and negative LR 0.34 (95% CI 0.66-0.15)]. Comparing microscopy and urine dipstick testing, using bacterial colony count on urine culture showed no significant difference between the two methods.

CONCLUSION

Urine dipstick testing is more effective for diagnosis of UTI in children over 2 years than for younger children.

Prevalence of urinary tract infection in childhood: a meta-analysis

BACKGROUND

Knowledge of baseline risk of urinary tract infection can help clinicians make informed diagnostic and therapeutic decisions. We conducted a meta-analysis to determine the pooled prevalence of urinary tract infection (UTI) in children by age, gender, race, and circumcision status.

METHODS

MEDLINE and EMBASE databases were searched for articles about pediatric urinary tract infection. Search terms included urinary tract infection, cystitis, pyelonephritis, prevalence and incidence. We included articles in our review if they contained data on the prevalence of UTI in children 0-19 years of age presenting with symptoms of UTI. Of the 51 articles with data on UTI prevalence, 18 met all inclusion criteria. Two evaluators independently reviewed, rated, and abstracted data from each article.

RESULTS

Among infants presenting with fever, the overall prevalence (and 95% confidence interval) of UTI was 7.0% (CI: 5.5-8.4). The pooled prevalence rates of febrile UTIs in females aged 0-3 months, 3-6 months, 6-12 months, and >12 months was 7.5%, 5.7%, 8.3%, and 2.1% respectively. Among febrile male infants less than 3 months of age, 2.4% (CI: 1.4-3.5) of circumcised males and 20.1% (CI: 16.8-23.4) of uncircumcised males had a UTI. For the 4 studies that reported UTI prevalence by race, UTI rates were higher among white infants 8.0% (CI: 5.1-11.0) than among black infants 4.7% (CI: 2.1-7.3). Among older children (<19 years) with urinary symptoms, the pooled prevalence of UTI (both febrile and afebrile) was 7.8% (CI: 6.6-8.9).

CONCLUSIONS

Prevalence rates of UTI varied by age, gender, race, and circumcision status. Uncircumcised male infants less than 3 months of age and females less than 12 months of age had the highest baseline prevalence of UTI. Prevalence estimates can help clinicians make informed decisions regarding diagnostic testing in children presenting with signs and symptoms of urinary tract infection.

Clinical management of fever in children younger than three years of age

The clinical management of febrile children continues to evolve, especially in the light of vaccines against Haemophilus influenzae type B and more recently, Streptococcus pneumoniae. These vaccines have decreased the risk of serious bacterial illness in most children, allowing for a more selective approach to investigation and empirical treatment. However, children younger than three months of age still require an aggressive approach to investigation and careful follow-up. Certain laboratory criteria can allow safe management of even young infants on an outpatient basis. The present article outlines an age-based approach to investigation and management of children with fever.

Urine microscopy as screen for urinary tract infections in a pediatric emergency unit in Chile

OBJECTIVE

To evaluate the accuracy of urine microscopy as a predictor of urinary tract infections (UTIs), taking the urine culture as a criterion standard in a pediatric emergency unit.

METHODS

Retrospective study in which all medical charts were analyzed for children younger than 15 years who underwent urine culture and sediment tests. Urine microscopy test was considered positive for leukocyturia when there were more than 10 leukocytes per microliter, and bacteriuria test was considered positive when any presence of bacteria was detected at x40 magnification. The method of sample taking was also recorded.

RESULTS

Of 18,302 consultations of children younger than 15 years, 1173 (6.4%) needed both a urine culture and a urine microscopy. Urine cultures demonstrated that 20.9% of the samples were consistent with the diagnosis of UTI. Bacteriuria and leukocyturia tests had a sensitivity of 87.4% (95% CI, 82.7%-91.0%), a specificity of 94.8% (95% CI, 93.2%-96.1%), a likelihood ratio for a positive test of 16.7 (95% CI, 16.18-17.61), and a likelihood ratio for a negative test of 0.13 (95% CI, 0.12-0.14). Samples taken by sterile methods (suprapubic aspiration and bladder catheterization) had a better positive predictive value than those taken by nonsterile methods (urine bag and midstream clean-catch) without having an adverse impact on the negative predictive value.

CONCLUSIONS

Urine microscopy without Gram stain is a good test for predicting the presence of UTIs in children, which supports the use of this screening method in pediatric emergency units.

A head-to-head comparison: "clean-void" bag versus catheter urinalysis in the diagnosis of urinary tract infection in young children

OBJECTIVE

To compare the validity of the urinalysis on clean-voided bag versus catheter urine specimens using the catheter culture as the "gold" standard.

STUDY DESIGN

This is a cross-sectional study of 303 nontoilet-trained children under age 3 years at risk for urinary tract infection (UTI) who presented to a children's hospital emergency department. Paired bag and catheter specimens were obtained from each child and sent for dipstick and microscopic urinalysis. Sensitivity and specificity were compared using McNemar's chi2 test for paired specimens and the ordinary chi2 test for unpaired comparisons.

RESULTS

The bag dipstick was more sensitive than the catheter dipstick for the entire study sample: 0.85 (95% confidence interval [CI]=0.78 to 0.93) versus 0.71 (95% CI=0.61 to 0.81), respectively. Both bag and catheter dipstick sensitivities were lower in infants < or =90 days old (0.69 [95% CI=0.44 to 0.94] and 0.46 [95% CI=0.19 to 0.73], respectively) than in infants >90 days old (0.88 [95% CI=0.81 to 0.96] and 0.75 [95% CI=0.65 to 0.86], respectively). Specificity was consistently lower for the bag specimens than for the catheter specimens: 0.62 (95% CI=0.56 to 0.69) versus 0.97 (95% CI=0.95 to 0.99), respectively.

CONCLUSIONS

Urine collection methods alter the diagnostic validity of urinalysis. These differences have important implications for the diagnostic and therapeutic management of children with suspected UTI.

Clinical and demographic factors associated with urinary tract infection in young febrile infants

OBJECTIVE

Previous research has identified clinical predictors for urinary tract infection (UTI) to guide urine screening in febrile children <24 months of age. These studies have been limited to single centers, and few have focused on young infants who may be most at risk for complications if a UTI is missed. The objective of this study was to identify clinical and demographic factors associated with UTI in febrile infants who are < or =60 days of age using a prospective multicenter cohort.

METHODS

We conducted a multicenter, prospective, cross-sectional study during consecutive bronchiolitis seasons. All febrile (> or =38 degrees C) infants who were < or =60 days of age and seen at any of 8 pediatric emergency departments from October through March 1999-2001 were eligible. Clinical appearance was evaluated using the Yale Observation Scale. UTI was defined as growth of a known bacterial pathogen from a catheterized specimen at a level of (1) > or =50000 cfu/mL or (2) > or =10000 cfu/mL in association with a positive dipstick test or urinalysis. We used bivariate tests and multiple logistic regression to identify demographic and clinical factors that were associated with the likelihood of UTI.

RESULTS

A total of 1025 (67%) of 1513 eligible patients were enrolled; 9.0% of enrolled infants received a diagnosis of UTI. Uncircumcised male infants had a higher rate of UTI (21.3%) compared with female (5.0%) and circumcised male (2.3%) infants. Infants with maximum recorded temperature of > or =39 degrees C had a higher rate of UTI (16.3%) than other infants (7.2%). After multivariable adjustment, UTI was associated with being uncircumcised (odds ratio: 10.4; bias-corrected 95% confidence interval: 4.7-31.4) and maximum temperature (odds ratio: 2.4 per degrees C; 95% confidence interval: 1.5-3.6). Factors that were reported previously to be associated with risk for UTI in infants and toddlers, such as white race and ill appearance, were not significantly associated with risk for UTI in this cohort of young infants.

CONCLUSIONS

Being uncircumcised and height of fever were associated with UTI in febrile infants who were < or =60 days of age. Uncircumcised male infants were at particularly high risk and may warrant a different approach to screening and management.

How does study quality affect the results of a diagnostic meta-analysis?

BACKGROUND

The use of systematic literature review to inform evidence based practice in diagnostics is rapidly expanding. Although the primary diagnostic literature is extensive, studies are often of low methodological quality or poorly reported. There has been no rigorously evaluated, evidence based tool to assess the methodological quality of diagnostic studies. The primary objective of this study was to determine the extent to which variations in the quality of primary studies impact the results of a diagnostic meta-analysis and whether this differs with diagnostic test type. A secondary objective was to contribute to the evaluation of QUADAS, an evidence-based tool for the assessment of quality in diagnostic accuracy studies.

METHODS

This study was conducted as part of large systematic review of tests used in the diagnosis and further investigation of urinary tract infection (UTI) in children. All studies included in this review were assessed using QUADAS, an evidence-based tool for the assessment of quality in systematic reviews of diagnostic accuracy studies. The impact of individual components of QUADAS on a summary measure of diagnostic accuracy was investigated using regression analysis. The review divided the diagnosis and further investigation of UTI into the following three clinical stages: diagnosis of UTI, localisation of infection, and further investigation of the UTI. Each stage used different types of diagnostic test, which were considered to involve different quality concerns.

RESULTS

Many of the studies included in our review were poorly reported. The proportion of QUADAS items fulfilled was similar for studies in different sections of the review. However, as might be expected, the individual items fulfilled differed between the three clinical stages. Regression analysis found that different items showed a strong association with test performance for the different tests evaluated. These differences were observed both within and between the three clinical stages assessed by the review. The results of regression analyses were also affected by whether or not a weighting (by sample size) was applied. Our analysis was severely limited by the completeness of reporting and the differences between the index tests evaluated and the reference standards used to confirm diagnoses in the primary studies. Few tests were evaluated by sufficient studies to allow meaningful use of meta-analytic pooling and investigation of heterogeneity. This meant that further analysis to investigate heterogeneity could only be undertaken using a subset of studies, and that the findings are open to various interpretations.

CONCLUSION

Further work is needed to investigate the influence of methodological quality on the results of diagnostic meta-analyses. Large data sets of well-reported primary studies are needed to address this question. Without significant improvements in the completeness of reporting of primary studies, progress in this area will be limited.

Rapid tests and urine sampling techniques for the diagnosis of urinary tract infection (UTI) in children under five years: a systematic review

BACKGROUND

Urinary tract infection (UTI) is one of the most common sources of infection in children under five. Prompt diagnosis and treatment is important to reduce the risk of renal scarring. Rapid, cost-effective, methods of UTI diagnosis are required as an alternative to culture.

METHODS

We conducted a systematic review to determine the diagnostic accuracy of rapid tests for detecting UTI in children under five years of age.

RESULTS

The evidence supports the use of dipstick positive for both leukocyte esterase and nitrite (pooled LR+ = 28.2, 95% CI: 17.3, 46.0) or microscopy positive for both pyuria and bacteriuria (pooled LR+ = 37.0, 95% CI: 11.0, 125.9) to rule in UTI. Similarly dipstick negative for both LE and nitrite (Pooled LR- = 0.20, 95% CI: 0.16, 0.26) or microscopy negative for both pyuria and bacteriuria (Pooled LR- = 0.11, 95% CI: 0.05, 0.23) can be used to rule out UTI. A test for glucose showed promise in potty-trained children. However, all studies were over 30 years old. Further evaluation of this test may be useful.

CONCLUSION

Dipstick negative for both LE and nitrite or microscopic analysis negative for both pyuria and bacteriuria of a clean voided urine, bag, or nappy/pad specimen may reasonably be used to rule out UTI. These patients can then reasonably be excluded from further investigation, without the need for confirmatory culture. Similarly, combinations of positive tests could be used to rule in UTI, and trigger further investigation.

Fever without apparent source on clinical examination

This section focuses on issues in infectious disease that are commonly encountered in pediatric office practices. Dr. McCarthy discusses recent literature regarding the evaluation and management of acute fevers without apparent source on clinical examination in infants and children and the evaluation of children with prolonged fevers of unknown origin. Drs. Klig and Chen (pp 121-126) review recent literature about lower respiratory infection in children. This section focuses on febrile children in whom a source of fever is not readily apparent on clinical examination. This issue is discussed in several contexts: recent developments concerning the epidemiology, pathophysiology, diagnostic approach, and therapy of febrile illnesses; children from 3 to 36 months of age with fever; infants younger than 90 days of age with fever; and children of any age with prolonged fever, usually lasting more than 7 to 10 days, for whom a diagnosis has not been established.