Arch dis child 2012-nigrovic-799-805

Arch Dis Child 2012;97:799–805. doi:10.1136/archdischild-2012-301798 799

Original article

1Division of Emergency Medicine, Department of Pediatrics, Children’s Hospital Boston and Harvard Medical School, Boston, Massachusetts, USA2Division of Infectious Diseases, Department of Pediatrics, Children’s Hospital Boston and Harvard Medical School, Boston, Massachusetts, USA3Departments of Emergency Medicine and Pediatrics, University of California, Davis School of Medicine,, Davis, California, USA

Correspondence to Lise E Nigrovic, Division of Emergency Medicine, Department of Pediatrics, Children’s Hospital Boston and Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA; [email protected]

This work was presented in part at the American Academy of Pediatrics, National Conference and Exhibition, 14 October 2011, Boston, Massachusetts, USA.

Received 1 February 2012Accepted 28 May 2012

ABSTRACTObjective The Bacterial Meningitis Score, a derived

and validated clinical decision rule, identifi es children

with cerebrospinal fl uid (CSF) pleocytosis who are at

very low risk of bacterial meningitis. Low-risk features

include the following: negative CSF Gram stain, CSF

absolute neutrophil count (ANC) <1000 cells/µl, CSF

protein <80 mg/dl, peripheral blood ANC <10 000

cells/µl and no seizure at or prior to initial presentation.

The study objective of the present work was to calculate

the performance of the Bacterial Meningitis Score by

performing a meta-analysis of all published validation

studies.

Methods A meta-analysis of all studies published

between 2002 and 2012 was performed, evaluating

the performance of the Bacterial Meningitis Score

in children with CSF pleocytosis. Study quality was

assessed using the assessment of diagnostic accuracy

studies instrument and then the test performance of the

prediction rule was calculated.

Results From 8 studies, 5312 patients were identifi ed,

of whom 4896 (92%) had suffi cient clinical data to

calculate the Bacterial Meningitis Score. Bacterial

meningitis was diagnosed in 1242 children (23% of study

patients). The combined sensitivity of the Bacterial

Meningitis Score for bacterial meningitis was 99.3%

(1224/1233; 95% CI 98.7% to 99.7%), specifi city 62.1%

(2274/3663; 95% CI 60.5% to 63.7%) negative predictive

value 99.7% (2274/2283, 95% CI 99.3% to 99.9%),

positive likelihood ratio 2.6 (95% CI 2.5 to 2.7) and

negative likelihood ratio 0.01 (95% CI 0.01 to 0.02).

Conclusions The Bacterial Meningitis Score is a highly

accurate clinical scoring system that could be used to

assist clinical decision making for the management of

children with CSF pleocytosis.

INTRODUCTIONIn regions of the world with high vaccination rates, the incidence of bacterial meningitis has declined substantially due to highly effective con-jugate vaccines.1–5 However, children with cere-brospinal fl uid (CSF) pleocytosis are frequently hospitalised and given broad-spectrum antibiotics while awaiting the results of bacterial cultures, which may take 48 h to reliably exclude bacterial growth.6–8

Children at very low risk for bacterial menin-gitis can be considered for outpatient manage-ment if they are otherwise well appearing and have adequate clinical follow-up. The Bacterial Meningitis Score clinical prediction rule was derived and internally validated from a retrospec-tive cohort of 696 children with CSF pleocytosis hospitalised at a single institution.9 Although the

Meta-analysis of bacterial meningitis score validation studiesLise E Nigrovic,1 Richard Malley,1,2 Nathan Kuppermann3

Bacterial Meningitis Score performed with very high accuracy, clinical application was limited by the small study sample size, single-centre design with a highly referred population, lack of external validation, as well as ongoing changes in the epi-demiology of bacterial meningitis related to the introduction of bacterial conjugate vaccines.5

The ‘real-world’ performance of a clinical pre-diction rule is most accurately assessed by its application in a variety of clinical settings. We initially tested the Bacterial Meningitis Score in a large multicentre US study of children with CSF pleocytosis.10 The Bacterial Meningitis Score has also been evaluated in six additional studies by independent investigators.11–16 In this study, we sought to measure the accuracy of the Bacterial Meningitis Score by aggregating the patients from the eight validation studies and to report the per-formance of the prediction rule in the combined population.

METHODSStudy designWe performed a fi xed-effects meta-analysis of the published Bacterial Meningitis Score validation studies.17 18 We searched the Medline and Embase electronic databases for eligible articles published between October 2002 and March 2012. We used the following search terms: Bacterial Meningitis Score, bacterial meningitis prediction and menin-gitis validation study. Additionally, we reviewed all publications that referenced the derivation study.9 One publication that is currently in press

What is already known on this subject

The Bacterial Meningitis Score, a previously derived and validated clinical prediction rule, identifi es children with cerebrospinal fl uid (CSF) pleocytosis who are at very low risk for bacterial meningitis.

What this study adds

The Bacterial Meningitis Score performed well in eight published validation studies and could be used to assist clinical decision making for children with CSF pleocytosis.

archdischild-2012-301798.indd 1archdischild-2012-301798.indd 1 7/13/2012 6:19:52 PM7/13/2012 6:19:52 PM

Published Online First4 July 2012

800 Arch Dis Child 2012;97:799–805. doi:10.1136/archdischild-2012-301798

Original article

as the I2 statistic to assess for consistency of the results across studies.

As a prespecifi ed subgroup analysis, we also calculated the performance of the Bacterial Meningitis Score in the sub-group of study patients not included in either the internal9 or the multicentre10 validation studies conducted by this study’s investigators.

We performed statistical calculations using Stata statistical software.24

RESULTSWe identifi ed 405 published studies using our search strategy of which 10 met our inclusion criteria. We excluded an adult cohort study (111 patients)25 and a paediatric cohort study (91 patients)26 because insuffi cient details were provided to allow us to assess the patient population or the antibiotic pretreat-ment status. We included the remaining eight studies in this analysis (table 2).9–16 We assessed the quality of the included studies using the QUADAS-2 instrument (table 3).22

The eight included studies had the following study designs: case series (one study),13 case-control (one study),12 retrospec-tive cohort (fi ve studies)9–11 14 16 and prospective cohort (one study).15 Study patients presented for emergency care in the USA,9 10 Western Europe11 12 and South America (Argentina).15 Of the 5312 included children, 1242 (23%) had bacterial men-ingitis and 4070 (77%) had aseptic meningitis.

The patient populations for each validation study varied slightly (table 4). One study was limited to patients with bac-terial meningitis13 and another had available procalcitonin results.14 Five studies were of hospitalised children, including patients referred for management of meningitis.9 11 12 14–16 One other study was conducted in the emergency department10 and the other was a nationwide meningitis registry (216 participating institutions).13 27 While Haemophilus infl uenzae type B vaccination rates were high in all study populations, only one population (USA) had widespread seven-valent pneumococ-cal conjugate vaccination available during the study period.10

28 None of the populations had routine meningococcal vacci-nation during the study period. All studies excluded children with immunosuppressive medical conditions or therapies, while the other exclusion criteria varied by study: critical illness,9 10 14–16 recent neurosurgery or presence of a ventricular shunt,9 10 12–16 purpura,9 10 focal bacterial infections requiring parenteral antibiotic treatment,9 10 traumatic LP,12 13 16 Lyme meningitis16 or transferred patients.16

While in all studies the bacterial meningitis case defi nition included patients with CSF culture positive for a bacterial pathogen, they varied in whether patients with a positive CSF Gram stain,12 latex agglutination test,12 14–16 CSF bacterial PCR test15 16 or CSF pleocytosis with a positive blood culture but negative CSF culture9–11 13 15 16 were considered to have bacte-rial meningitis. Although patients pretreated with antibiotics were excluded, the time between antibiotic administration and diagnostic LP defi ned as antibiotic pretreatment was not standardised.

The Bacterial Meningitis Score could be calculated for 4896 (92%) of the 5312 patients in the aggregated patient population (table 5). Patients from all studies contributed to the calculation of test sensitivity. Patients from seven studies were included in the calculation of test specifi city and from six studies in the predictive value and likelihood ratio calculations. The Bacterial Meningitis Score had an overall test sensitivity of 99.3% (95% CI 98.7 to 99.7%) (fi gure 1). For the primary outcome measure (sensitivity), we found no evidence for heterogeneity between

was identifi ed by a published abstract and we subsequently communicated with the corresponding author. We reviewed potentially eligible studies to identify those that included chil-dren younger than 18 years of age as well as suffi cient informa-tion to calculate the Bacterial Meningitis Score. We excluded patients used for the prediction model derivation conducted by the study investigators.9

Data collectionWe reviewed eligible studies to determine study design, inclu-sion and exclusion criteria, patient population and case defi -nitions. Because antibiotic pretreatment can render bacterial cultures falsely negative19 20 and also impact CSF profi les,21 we excluded studies in which patients had received antibiot-ics prior to lumbar puncture (LP) (defi ned as ‘antibiotic pre-treatment’). We contacted the corresponding authors of the published studies to clarify study methods, as necessary. We excluded studies for which we could not verify study proce-dures. We assessed the quality of the included studies using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) instrument.22

Bacterial meningitis score performanceFor each of the included studies, we determined the number of patients with bacterial and aseptic meningitis using study-spe-cifi c case defi nitions. Children with none of the fi ve high-risk Bacterial Meningitis Score predictors were classifi ed at ‘very low risk’ for bacterial meningitis (table 1).9 10 Children with one or more high-risk predictor were classifi ed as ‘not low risk’ even if other predictors were missing. Otherwise, children missing predictors included in the Bacterial Meningitis Score were excluded from the prediction rule validation.

Statistical analysisWe abstracted the Bacterial Meningitis Score as calculated by the study investigators. We then calculated the performance of the dichotomised Bacterial Meningitis Score (‘very low risk’ vs ‘not very low risk’) in the aggregated patient population. Our primary outcome was the prediction rule sensitivity, which we calculated for each of the included studies. Our secondary outcomes were specifi city, negative predictive value (NPV), positive predictive value (PPV) as well as positive and nega-tive likelihood ratios. We used patients from case-control and cohort studies for calculation of sensitivity and specifi city, but not for PPV and NPV. We used children from cohort studies for the calculation of sensitivity, specifi city, NPV, PPV as well as likelihood ratios using standard techniques.23

We present the pooled effects as a point estimate with 95% CI using binomial methods with a Forest plot for the primary outcome measure. We calculated the Q statistic (χ2-distributed with one less than the number of included studies degrees of freedom) to assess the heterogeneity between studies as well

Table 1 Bacterial Meningitis Score9

Bacterial Meningitis Score predictors Criteria

CSF Gram stain Positive resultCSF ANC ≥1000 cells/mm3

CSF protein ≥80 mg/dlPeripheral blood ANC ≥10 000 cells/mm3

Seizure Onset at or prior to time of presentation

ANC, absolute neutrophil count; CSF, cerebrospinal fl uid.



Original article

Table 2 Published Bacterial Meningitis Score validation studies

Study Journal Study years

Bacterial meningitis, N (%)

Aseptic meningitis, N (%) Study design

Admission rate, % Country

PCV7 implemented

Nigrovic et al9 Pediatrics 1994–2000 38 (16%) 196 (84%) Single-centre retrospective cohort

100% USA No

Dubos et al12 Arch Dis Child 1995–2004 20 (12%) 146 (88%) Retrospective with selected cases and controls

100% France No

Piérart and Lepage11 Rev Med Liege 2000–2005 29 (10%) 248 (90%) Retrospective cohort 100% Belgium NoNigrovic et al10 JAMA 2002–2004 121 (4%) 3174 (96%) A 20-centre retrospective

cohort 81% USA Yes

Dubos et al13 J Pediatr 2001–2005 898 (100%) 0 (0%) Nationwide meningitis registry 100% France NoDubos et al14 Arch Dis Child 1996–2005 96 (48%) 102 (52%) A six-centre retrospective

cohort100% Western

EuropeNo

Agüero et al15 Arch Argent Pediatr

2006–2007 14 (20%) 56 (80%) Single-centre prospective cohort

100% Argentina No

Tuerlinckx et al16 Acta Clinica Belgica

1996–2008 26 (15%) 148 (85%) A two-centre retrospective cohort

100% Belgium No

Totals 1242 (23%) 4070 (77%) 88%

PCV7, seven-valent pneumococcal conjugate vaccine.

Table 3 Quality assessment of diagnostic accuracy studies 222

Study

Risk of bias Applicability concerns

Patient selection Index test

Reference standard

Flow and timing

Patient selection Index test

Reference standard

Nigrovic et al9 ☺ ☺ ☺ ☺ ☺ ☺ ☺Dubos et al12 ☻ ☺ ? ☺ ☻ ☺ ?Piérart and Lepage11 ☺ ☺ ☺ ☺ ☺ ☺ ☺Nigrovic et al10 ☺ ☺ ☺ ☺ ☺ ☺ ☺Dubos et al13 ☺ ☺ ☺ ☺ ☺ ☺ ☺Dubos et al14 ☺ ☺ ☺ ☺ ☺ ☺ ☺Agüero et al15 ☺ ☺ ☺ ☺ ☺ ☺ ☺Tuerlinckx et al16 ☺ ☺ ☺ ☺ ☺ ☺ ☺

☺, low risk; ☻, high risk; ?, unclear risk.

Table 4 Study defi nitions

Study Patient population Inclusion criteria Exclusion criteria Bacterial meningitis defi nition

Pretreated patients included?*

Nigrovic et al9 Hospitalised patients CSF WBC ≥8 cells/mm3

Positive CSF cultureAge 1 month to 18 years

Critical illnessNeurosurgery or shuntImmunodefi ciencyFocal bacterial infectionsPurpura fulminans

Positive CSF culture

CSF pleocytosis plus positive blood culture

No

Dubos et al12 Hospitalised patients CSF WBC ≥7 cells/mm3 Neurosurgical disease Positive CSF Gram stain, culture or latex agglutination

NoImmunodefi ciency

Age 1 month to 16 years Traumatic LPReferred patients

Piérart and Lepage 11

Hospitalised patients CSF WBC ≥6 cells/mm3 Tuberculosis or Lyme meningitis Positive CSF culture or bacterial PCR NoAge 1 month to 15 years Immunosuppression CSF pleocytosis plus positive blood culture

Nigrovic et al10 Emergency department patients

CSF WBC ≥10 cells/mm3 Critical illness Positive CSF culture NoNeurosurgery or shunt CSF pleocytosis plus positive blood cultureImmunodefi ciency

Positive CSF culture Focal bacterial infectionsAge 1 month to 18 years Purpura

Dubos et al13 Bacterial meningitis registry

CSF WBC ≥7 cells/mm3 Critical illness Positive CSF culture or latex agglutination NoNeurosurgery or shunt

Age 1 month to 18 years Immunodefi ciency CSF pleocytosis plus positive blood cultureTraumatic LP

Dubos et al14 Hospitalised patients CSF WBC ≥8 cells/mm3 Critical illness Positive CSF culture, latex agglutination or bacterial PCR

No

Neurosurgery or shuntAge 1 month to 18 years Immunodefi ciency CSF pleocytosis plus positive blood culture

Procalitonin obtained Focal bacterial infections

(Continued)



Original article

Table 4 (Continued)

Study Patient population Inclusion criteria Exclusion criteria Bacterial meningitis defi nition

Pretreated patients included?*

Agüero et al15 Hospitalised patients CSF WBC ≥8 cells/mm3 Critical illness Positive CSF culture NoNeurosurgery or shunt

Age 1 month to 18 years Immunodefi ciency CSF pleocytosis plus positive blood culture, bacterial PCR or latex agglutinationFocal bacterial infections

Tuerlinckx et al16 Hospitalised patients CSF WBC ≥9 cells/mm3 Critical illness Positive CSF culture NoPurpuraNeurosurgery CSF pleocytosis plus positive blood culture,

bacterial PCR or latex agglutinationImmunodefi ciencyTraumatic LP

Lyme meningitis

*Pretreatment defi ned as antibiotics administered before lumbar puncture.CSF, cerebrospinal fl uid; LP, lumbar puncture; WBC, white blood cells.

studies (p=0.88) or results (I2=0.0) in our meta-analysis. Children categorised as ‘not very low risk’ by the Bacterial Meningitis Score had a positive likelihood ratio for bacterial meningitis of 2.6 (95% CI 2.5 to 2.7) and those categorised as ‘very low risk’ by the Bacterial Meningitis Score had a negative likelihood ratio of 0.01 (95% CI 0.01 to 0.02).

Among the 1783 children included in the 6 validation stud-ies not conducted by this study’s investigators, 1083 (61%) had bacterial meningitis and 700 (39%) had aseptic meningitis. In this subgroup, the Bacterial Meningitis Score had a sensitivity of 99.3% (95% CI 98.6% to 99.7%), specifi city of 61.0% (95% CI 57.3 to 64.7%), NPV of 98.3% (95 CI 96.6% to 99.3%) and PPV 28.1% (95% CI 22.6% to 33.9%). We could not exclude the possibility that children with bacterial meningitis from 1 of the 216 centres in the bacterial meningitis registry13 may also have been included in a more recent multicentre retrospec-tive cohort study (personal communication, M. Chalumeau, Hôpital de Paris). However, when we excluded this cohort study, the Bacterial Meningitis Score performed similarly (data not shown).

Nine patients with bacterial meningitis were classifi ed as ‘very low risk’ by the Bacterial Meningitis Score (table 5). Of these, three were younger than 2 months of age (an age at which we previously recommended the Bacterial Meningitis Score not be applied)10 and three others presented with petechiae or purpura on examination.13 The three misclassifi ed patients with bacterial meningitis who were older than 2 months and who did not have a petechial or purpuric rash on presenting examination are described in table 6 (patients 3, 6 and 9). All three of these children had meningococcal meningitis.

DISCUSSIONThe Bacterial Meningitis Score, a clinical prediction rule to identify children with CSF pleocytosis who are at very low risk of bacterial meningitis, has been validated in eight published studies.9–16 In this meta-analysis, the score had a sensitivity of 99.3% (95% CI 98.7% to 99.7%) for bacterial meningitis. The included studies were of high quality and did not have signifi -cant study heterogeneity. Although the study designs, patient population, inclusion and exclusion criteria as well as bacterial meningitis case defi nition differ between studies, the Bacterial Meningitis Score performed with a high degree of accuracy. When the validation studies conducted by this study’s investi-gators were excluded, the results did not change.

A clinical prediction rule is a decision-making tool that com-bines history, physical examination and laboratory results to predict the probability of an outcome for an individual patient. Clinical prediction rules must be developed and validated according to rigorous methodological standards prior to wide-spread implementation.29–31 While prospective rather than retrospective validation is typically preferred, because of the rarity of bacterial meningitis in high-income countries,5 such a validation is not readily feasible; accordingly, seven of the eight included studies were retrospective. We do not believe that the retrospective validation introduced important biases since the predictors are objective. Four of the fi ve factors are laboratory values and one clinical factor (seizure at or prior to the time of initial presentation), should be reliably recorded in the medical records.32 33

For children younger than 18 years of age in the USA, the incidence of bacterial meningitis caused by H infl uenzae, Streptococcus pneumoniae, group B streptococcus (GBS), Neisseria meningitidis or Listeria monocytogenes declined 31% over the past decade.5 Despite these substantial declines in the overall inci-dence, the bacterial meningitis case death rate has remained unchanged at 7%; most affected children do not have pre-disposing medical conditions.5 Given the high mortality and morbidity, clinicians must still maintain a high index of sus-picion for bacterial meningitis. Looking ahead, the increasing availability of the 13-valent S pneumoniae and quadrivalent N meningitidis conjugate vaccines in high-income countries will further decrease the incidence of bacterial meningitis. The Bacterial Meningitis Score can support clinician decision mak-ing by providing a highly accurate initial assessment of the risk of bacterial meningitis for children with CSF pleocytosis.

We recommend that the Bacterial Meningitis Score, as with other clinical prediction rules, be used to assist rather than replace clinical decision making.34 Although the score per-forms extremely well, it is highly unlikely to develop a clinical prediction rule with 100% accuracy in all patient populations.35 Of note, the misclassifi ed patients who presented without petechia or purpura all had meningococcal meningitis which has been previously described to present without CSF pleocy-tosis.36 Nevertheless, children with a very low-risk Bacterial Meningitis Score are at such low risk of bacterial meningi-tis that they may be considered for outpatient management, potentially after the administration of a long-acting parenteral antibiotic. Currently, most children with CSF pleocytosis are



Original article

hospitalised and given parenteral antibiotics in order to avoid missing the very few with bacterial meningitis. Application of the Bacterial Meningitis Score could substantially reduce unnecessary hospitalisation of children with aseptic meningi-tis, while still providing a safety margin by the administration of long-acting antibiotic prior to culture results. As we have previously recommended,10 however, the Bacterial Meningitis Score should not be applied to ill-appearing children, infants 2 months and younger, in whom the risk of bacterial meningitis is highest5 and to those with physical examinations sugges-tive of invasive bacterial infection (eg, those with petechiae or purpura).37 This approach will further reduce the risk of mis-classifi cation of children with bacterial meningitis.

Furthermore, biologic markers of infl ammation have been investigated for their ability to discriminate between cases of bacterial and aseptic meningitis. For example, CSF lactate38 39 and serum procalcitonin40 41 are higher in children with bacterial than aseptic meningitis, although there is overlap in levels of these bio-markers. Diagnostic assays that use RNA expression to identify host response to specifi c pathogens are currently being studied in the clinical setting.42–44 In the future, these novel assays might allow rapid identifi cation of specifi c meningitis pathogens, or host responses associated with bacterial meningitis.

Our study has some limitations. First, as most of the vali-dation studies were retrospective, we could not evaluate the general appearance of the patients, which plays an important role in clinical decision making. Certain clinical factors such as the presence of petechiae or purpura could not be evalu-ated in all studies. Nevertheless, the accuracy of the Bacterial Meningitis Score remained very high in each of the evaluated studies. Second, we were only able to include children who had suffi cient clinical data to apply the Bacterial Meningitis Score from published validation studies. Given the number of patients evaluated in these studies and the objective nature of the variables in the score, it is unlikely that the model would have performed substantially differently in patients with missing variables. Third, we could not exclude the pos-sibility that a few children with bacterial meningitis from a single centre may have been represented in two included studies.13 14 However, the prediction model performed simi-larly if this recent study was excluded (and therefore eliminat-ing the possibility of patient redundancy). Fourth, we were unable to include patients from the case-control or registry studies in the calculations of NPV, PPV or likelihood ratios as these calculations require population prevalence. The variabil-ity between experimental defi nitions and methods may have reduced our ability to accurately combine the study patients. However, the similar performances of the model across a wide variety of clinical settings and patient populations as well as the lack of heterogeneity in the sensitivity and NPV estimates increase the generalisability of our fi ndings. Furthermore, we recognise that there is a preponderance (almost two-thirds) of patients from a single validation study.10 To address a poten-tial skewing effect, we performed an additional subgroup analysis after excluding studies conducted by this study’s investigators, and found similar results to the main analysis. Finally, the Bacterial Meningitis Score does not predict the likelihood of other central nervous system infections such as herpes simplex virus, Lyme45–47 or tuberculous meningi-tis. Therefore, this clinical prediction rule should be used in concert with careful clinical assessment of the patient, which would include consideration of these other important treat-able infections.

Tabl

e 5

Perf

orm

ance

of t

he B

acte

rial M

enin

gitis

Sco

re (B

MS)

Stud

y

No.

of b

acte

rial

m

enin

gitis

cas

es

with

ver

y lo

w

risk

BM

S (=

0)

No.

of a

sept

ic

men

ingi

tis c

ases

w

ith v

ery

low

ris

k B

MS

(=0)

No.

of b

acte

rial

m

enin

gitis

cas

es

with

not

low

ris

k B

MS

(≥1)

No.

of a

sept

ic

men

ingi

tis c

ases

w

ith n

ot lo

w r

isk

BM

S (≥

1)Se

nsit

ivit

y %

(95%

CI)

Spec

ifi ci

ty %

(95%

CI)

Neg

ativ

e pr

edic

tive

valu

e %

(95%

CI)

Posi

tive

pred

ictiv

e va

lue

% (9

5% C

I)

Nig

rovi

c et

al9

014

438

5210

0% (9

1% to

100

%)

42%

(34%

to 5

1%)

100%

(98%

to 1

00%

)42

% (3

2% to

53%

)Du

bos

et a

l120

8620

4510

0% (8

4% to

100

%)

66%

(57%

to 7

3%)

NA

NA

Piér

art a

nd L

epag

e110

163

2985

100%

(88%

to 1

00%

)66

% (6

0% to

71%

)10

0% (9

6% to

100

%)

25%

(18%

to 3

4%)

Nig

rovi

c et

al10

217

1211

910

70 9

8% (9

4% to

100

%)

62%

(60%

to 6

3%)

99.

9% (9

9.6%

to 1

00%

)11

% (9

% to

13%

)Du

bos

et a

l135

NA

884

NA

99%

(99%

to 1

00%

)N

AN

AN

ADu

bos

et a

l140

5396

4910

0% (9

6% to

100

%)

52%

(42%

to 6

2%)

NA

NA

Agü

ero

et a

l150

2514

3110

0% (7

8% to

100

%)

69%

(58%

to 8

0%)

100%

(94%

to 1

00%

)31

% (1

8% to

47%

)Tu

erlin

ckx

et a

l162

9124

57 9

2% (7

5% to

99%

)61

(53%

to 6

9%)

98%

(92%

to 1

00%

)30

% (2

0% to

41%

)To

tal

922

7412

2413

89 9

9.3%

(98.

7% to

99.

7%)

62.1

% (6

0.5%

to 6

3.7%

) 9

9.6%

(99.

3% to

99.

8%)

28.1

% (2

2.6%

to 3

3.9%

)

NA

, not

app

licab

le.



Original article

ConclusionsIn summary, the Bacterial Meningitis Score performed with a high degree of diagnostic accuracy in eight validation studies. This score, in conjunction with clinical judgment can identify chil-dren with CSF pleocytosis who are at very low risk for bacterial meningitis. To minimise misclassifi cation of children with bacte-rial meningitis, we recommend that the Bacterial Meningitis Score only be applied to non-ill-appearing children older than 2 months, who do not have either petechiae or purpura on examination and have not been pretreated with antibiotics. For those children at very low risk, who have adequate clinical follow-up, clinicians could consider outpatient treatment after administration of a long-acting parenteral antibiotic. Future studies should focus on the implementation of the Bacterial Meningitis Score to prospectively identify children who are at very low risk of bacterial meningitis.

Contributors LEN conceived the study and drafted the manuscript. LEN, RM and NK conducted the data analysis, interpreted the data and critically reviewed the manuscript.

Acknowledgements The authors would like to thank Michael C Monuteaux ScD (Division of Emergency Medicine, Children’s Hospital; Boston, Massachusetts, USA) for his help with statistical analysis.

Competing interests None.

Provenance and peer review Not commissioned; externally peer reviewed.

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Table 6 Characteristics of children with bacterial meningitis who were misclassifi ed as very low risk by the Bacterial Meningitis ScorePatient no. Study

Patient age (years)

Petechiae or purpura

History of seizure

Peripheral ANC (cells/µl)

CSF ANC (cells/µl)

CSF protein (mg/dl)

Gram stain positive Bacterial pathogen

1 Nigrovic et al10 0.2 No No 8100 0 31 No Escherichia coli2 Nigrovic et al10 0.1 No No 6800 497 65 No Escherichia coli3 Dubos et al13 0.3 No No 7744 13 61 No Neisseria meningitidis4 Dubos et al13 0.7 Yes No 3600 32 25 No Neisseria meningitidis5 Dubos et al13 5.4 Yes No 9400 30 30 No Neisseria meningitidis6 Dubos et al13 3.4 No No 1517 60 20 No Neisseria meningitidis7 Dubos et al13 0.1 No No 3270 ≤8 46 No Streptococcus pneumoniae8 Tuerlinckx et al16 2.5 Yes No 7683 26 21 No Neisseria meningitidis9 Tuerlinckx et al16 15 No No 7689 22 46 No Neisseria meningitidis

ANC, absolute neutrophil count; CSF, cerebrospinal fl uid.

Figure 1 Forest plot showing Bacterial Meningitis Score sensitivity with 95% CI for individual studies (and a pooled estimate).



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Health & Medicine

Arch dis child 2012-nigrovic-799-805