Our analysis is the first to describe national variation in performance of LPs for EONS among normal-birth weight infants. These variations are significant and persist even with adjustments for potential confounding factors. Such variations in care indicate inconsistent application of available clinical guidelines, and also suggest broad opportunities for improvement in the delivery of neonatal care related to concerns about infection.
Lumbar punctures are invasive procedures and have been noted to be more difficult to perform in neonates than in other populations and to cause neonatal distress [16
]. In this population, complications such as “bloody taps” [17
] and contaminated specimens [5
] are common, and therefore limiting a newborn’s exposure to an LP may be desirable. On the other hand, some studies suggest that LPs performed only on newborns with signs of infection lead to missed diagnoses of meningitis and its associated morbidity [7
]. Still other studies have found discordance of cerebral spinal fluid and blood cultures in septic patients [18
], suggesting all newborns suspected of EONS should have LPs.
Both the CDC [9
] and the AAP [15
] have published guidelines to assist clinicians in the diagnostic evaluation of a newborn suspected of having GBS EONS. Variation in LPs in this analysis suggests that adoption of these guidelines is uneven. While it is impossible to delineate from our findings which group is performing the “clinically appropriate” number of LPs, inconsistency across clinicians practicing in different settings is evident.
Variation in both practice [12
] and clinical outcomes [20
] among neonatal intensive care units has been described previously. However, no study has exclusively compared children’s hospitals versus non-children’s hospitals when comparing LPs performed on neonates. Our study finds that LPs were done more frequently in children’s hospitals in two of our three study years, even after controlling for confounders. Even with this, it is possible that differences between children’s and non-children’s hospitals found in our study occurred because of unexplained confounding. For example, despite our broad inclusion of clinical diagnoses, it is plausible that newborns admitted to children’s hospitals have more serious or more complex illness, prompting more frequent LPs.
Our study also found some patient-level variables associated with LPs for EONS – in particular, insurance status. In one study year (2006), uninsured newborns were more likely to have LPs performed than those who were privately insured. This is potentially linked to maternal insurance status in the antenatal period. Mothers who are uninsured are less likely to utilize prenatal services [22
], thus less is known about their risks of peripartum infection. In this setting of uncertainty, neonatal providers might be more likely to perform LPs. We also found that newborns with Medicaid were more likely to have an LP for EONS in all study years. In this case, it is possible that insurance status is a proxy for race/ethnicity, because national enrollment data indicate that black and Hispanic children have proportionately higher rates of enrollment in Medicaid [23
]. It has been previously described that minority groups are disproportionately affected by GBS EONS [10
], therefore leading to the possibility that they were more likely to undergo LPs to evaluate for the condition.
Our study found geographic variation in the practice of performing LPs for EONS, with the Northeast having a statistically significant higher rate of LPs performed in 2003 and 2006, and a trend to more LPs in 2009. While no prior study has evaluated geographic variation in the practice of LPs for EONS, previous analyses have found geographic differences in other procedures such as placement of intracranial pressure monitors [24
] and tracheostomy [25
]. Such regional variation may reflect variation in pediatrician and/or neonatologist training or differences in epidemiologic patterns that influence clinicians’ perception of EONS risk.
Our study finds that more LPs sometimes led to more diagnoses of meningitis. As an example, newborns enrolled in state Medicaid programs were more likely than privately insured infants to have an LP performed and were more likely to have a diagnosis of meningitis. This finding also occurred in urban and teaching hospitals. In contrast, our study found that LPs were more commonly performed in the Northeast with no difference noted in the diagnosis of meningitis among the four census regions. One would expect that more LPs would lead to more diagnoses of meningitis; however, this finding was not consistent, suggesting the possibility that excess LPs are being performed. This inconsistency merits further study.
In fall of 2010, the CDC released updated guidelines for the diagnostic evaluation of newborns at risk of GBS EONS. The guidelines clarify that only a limited evaluation (blood culture and empiric antibiotics) should be completed for a newborn without signs of sepsis whose mother is diagnosed with chorioamnionitis (no LP). Additionally, it recommends observation for term newborns who are well-appearing without prolonged rupture of membranes (even if their mothers met criteria for intrapartum antibiotics and they were not received), potentially limiting antibiotic use in this group [19
]. The introduction of these new recommendations and the clarifications in the treatment algorithm provided in the guidelines might lead to more standard care and ensure LPs are performed judiciously.
There are limitations to our study common to analyses of secondary data. Our study utilized a nationally representative administrative dataset, which relies on hospital discharge abstracts. The use of these data allows for nationally representative inferences, but administrative data are subject to errors of omission and commission related to coding discrepancies. We did not have access to medical records for these patients that would have allowed us to validate the codes. Because race was missing in approximately one-quarter of our data, we were not able to evaluate the potential impact of race on our primary outcome, an important limitation.
In addition, discharge abstracts do not contain admitting diagnoses. Final billing diagnoses may not fully reflect clinical conditions or co morbidities present at the time of birth that may have influenced clinical decisions such as LPs. On the other hand, discharge abstracts likely reflect conditions most relevant to the clinical course of the infants. KID data are available at the encounter level rather than the patient level; therefore, we are unable to evaluate readmissions to look for possible missed cases of meningitis.