Comparing the Use of, and Considering the Need for, Lumbar Puncture in Children With Influenza or Other Respiratory Virus Infections

Gulam Khandaker; Leon Heron; Harunor Rashid; Jean Li-Kim-Moy; David Lester-Smith; Alison Kesson; Mary McCaskill; Cheryl Jones; Yvonne Zurynski; Elizabeth J. Elliott; Dominic E. Dwyer; Robert Booy

Disclosures

Influenza Resp Viruses. 2013;7(6):932-937. 

In This Article

Discussion

Our study suggests that, whereas the risk of SBI (bacterial meningitis or bacteraemia) was very low in children with either influenza or ORVIs, the rate of performing invasive procedures was significantly higher in children with influenza compared with those with ORVIs. Furthermore, whereas clinicians are more inclined to perform LP if, for example, a child is younger, has had a febrile convulsion or has a high fever, multivariate analysis showed that the only two independent predictors of LP were a diagnosis of influenza and age <3 months. Other studies have shown that the risk of SBI is very low in children with respiratory viral infection, but have not addressed whether influenza is a strong predictor of LP being performed.[6,7,13] For example, a prospective multicentre cross-sectional study, conducted in the USA over 3 years from 1998 to 2001, showed that the risk of SBI in young infants was significantly lower in children with influenza compared with those without influenza.[6] Another retrospective study, conducted over four consecutive influenza seasons in the USA, demonstrated that febrile children with influenza had a lower prevalence of bacteraemia, UTI, consolidative pneumonia or any SBI compared with those without influenza.[7] The rate of SBI in young infants with RSV was also lower compared with those without RSV.[8]

Despite a very low prevalence of SBI, this study demonstrates that children with influenza had significantly higher utilisation of invasive diagnostic procedures, particularly LP. This can partly be explained by the fact that children with influenza presented appearing more unwell as manifested by their higher mean temperature (38·6 versus 38°C, P < 0·01) and mean heart rates (160 versus 152, P < 0·01). This suggests that the children with influenza look clinically more unwell, and their presentation mimics SBI, including meningitis, and so full septic workups, including LP, are performed on presentation. This is consistent with other studies conducted in our hospital in a previous winter and one conducted elsewhere, both showing that about one-fourth of the children with influenza underwent a LP.[3,7]

A seasonal pattern for performing blood cultures and LP was observed in this study, the peak of which corresponded with that of influenza infections (Figure 2). There were, however, no cases of meningitis associated with influenza, although admittedly the numbers in our study are not large, and in our view, a systematic review of influenza and serious concomitant infection is indicated to further address this question. Our study is important in finding that the risk of SBI in children with influenza or ORVIs was low during a busy winter season, and yet, children with influenza undergo significantly higher number of invasive diagnostic procedures on presentation that might be reduced by improved ascertainment of influenza directly on admission. There are high rates of immunisation against pneumococcal, Hib and meningococcal C disease in Western Sydney, which explains why bacterial meningitis is now rare.[14]

Our study shows that about 17% of the children in the influenza group were younger than 3 months of age, while only 6% in the ORVI group were <3 months (P < 0·01). However, overall, about half of the children in either group were aged <1 year (Figure 1). This is consistent with findings from other studies.[15–17] Many of the influenza cases in our study were too young to be immunised against influenza. Considering the high burden of influenza in young children and the frequent use of invasive diagnostic procedures, it is important to consider how to rapidly screen febrile children with respiratory symptoms during the influenza season, for example, with a rapid diagnostic test. Indeed, a rapid diagnostic test (QuickVue Influenza A + B; Quidel Corporation, San Diego, CA, USA) performed on nasopharyngeal aspirates evaluated at our hospital during the 2009 pandemic season was found to be both sensitive and specific (84% and 98·4%, respectively) compared with nucleic acid testing.[18] Studies conducted elsewhere also have shown good sensitivity and specificity,[19] but some rapid diagnostic tests perform better than others and their sensitivities, particularly, may vary according to the swab type, influenza virus strain and patients' age.[20] As children with confirmed influenza were very unlikely to suffer from meningitis, rapid screening for influenza during the influenza season may greatly reduce the need for LP; this may have economic benefits too. A study from Spain has shown that patients positive for influenza, using a rapid diagnostic test in the emergency department, had a significantly reduced rate of hospitalisation compared with those who were negative.[21] A US study found that using influenza status alone, as a screening test for infants with SBI (with a positive influenza test being indicative of low risk for SBI), resulted in a negative predictive value of 97·5% (95% CI 93·0–99·2%).[6] From a clinical perspective, if the admitting consultant paediatrician were to review in person all cases being considered for LP, as occurs, for example, in Finland (T. Heikkinen, personal communication), the proportion undergoing the procedure may well be reduced. Notwithstanding, if meningitis is clinically suspected, the clinician should act accordingly, irrespective of the outcome of influenza diagnostic tests.

Other respiratory virus infections were more likely to present between 3 and 12 months of age, to require more oxygen on admission and a longer stay in hospital: this may relate to a greater proportion having bronchiolitis or viral pneumonitis than the influenza cases did. Most of the influenza cases (89·3%) in our study presented during July and August, the southern hemisphere winter influenza season. Clinicians should consider a diagnosis of influenza in febrile unwell children presenting during peak months of influenza activity.

There are some limitations in our study. Firstly, DFA and virus culture were employed for diagnosing respiratory viruses as that was the practice in 2007 at our hospital. Owing to lower sensitivity of these tests compared with nucleic acid tests,[22] some respiratory viral infections may have been missed; however, that being the case, it may help to better explain the apparent close association between the peaks of influenza diagnosis and performance of LP. Direct fluorescent antibody and other rapid antigen tests may provide more rapid turnaround times than nucleic acid testing, thus allowing LP to be avoided. Another limitation is that other respiratory viruses like rhinovirus, coronavirus, enterovirus, human metapneumovirus (hMPV) and human bocavirus were not looked for.

A systematic review addressing the risk of concomitant influenza and bacterial meningitis should be performed. Rapid screening of febrile infants with respiratory symptoms during periods of known influenza activity may help to avert the use of LP, particularly if these cases are clinically reviewed by the senior admitting consultant, who, if still suspicious of concomitant bacterial meningitis, can ensure the LP is performed.

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