Table 2.

Univariate analysis of factors associated with increased length of stay among infants 56 days of age or younger who underwent lumbar puncture.

Variable	Unadjusted Incidence Rate Ratio	95% Confidence Interval	P-value
Age Category
29–56 days	Reference	-	-
≤28 days	2.43	2.11–2.81	<0.001
Male sex	0.94	0.81–1.09	0.397
Race
Non-Hispanic White	Reference	-	-
Non-Hispanic Black	0.72	0.62–0.85	<0.001
Hispanic	1.65	1.11–2.45	0.014
Other	0.60	0.45–79	<0.001
Presenting during enterovirus season	0.97	0.84–1.13	0.695
Transported from other institution	3.18	2.69–3.76	<0.001
Birth History
Premature birth	2.49	2.04–3.03	<0.001
Cesarean section delivery	1.33	1.13–1.57	0.001
History of Present Illness
Apnea	1.91	1.45–2.52	<0.001
Upper Respiratory Symptoms	1.05	0.99–1.12	0.091
Gastro-intestinal symptoms	0.55	0.47–0.65	<0.001
Physical Examination
Tachypnea	2.04	1.44–2.89	<0.001
Hypoxia	2.32	1.55–3.49	<0.001
Hypotension	3.64	2.58–5.12	<0.001
Lethargy or irritability	1.02	0.84–1.23	0.868
Seizure	1.84	1.44–2.36	<0.001
Interventions/Studies Obtained
Required vasopressors	7.02	3.49–14.13	<0.001
Required intubation	7.61	5.68–10.22	<0.001
CSF HSV PCR sent	2.89	2.51–3.33	<0.001
Laboratory Results
Serious bacterial infection	1.65	1.26–2.17	<0.001
Hyponatremia	3.01	1.61–5.67	0.001
Peripheral WBC count ≥15,000 mm3	2.31	1.91–2.79	<0.001
Thrombocytopenia	3.11	2.09–4.64	<0.001
Low CSF glucose	2.15	1.64–2.81	<0.001
Elevated CSF protein	1.41	1.16–1.71	<0.001
CSF pleocytosis	2.16	1.84–2.53	<0.001
Traumatic lumbar puncture	1.14	0.98–1.32	0.082

Abbreviations: CSF, cerebrospinal fluid; HSV, herpes simplex virus; PCR, polymerase chain reaction; WBC, white blood cell count