Table 2.

Parsimonious Models Predicting Fever

SDNN (Primary HRV Metric)
Variable	OR	CI 95%	P-value
Occurrence of Fever
HRV by SDNN, msec	0.92	0.87–0.97	0.002
Admission GCS	0.88	0.78–1.01	0.060
Initial Graeb Score	1.15	1.01–1.31	0.032
Ventilator Free Days	0.91	0.84–0.98	0.010
Pneumonia	9.16	1.94–43.4	0.005
Lobar Hematoma	1.81	0.95–3.45	0.070
History of Hypertension	0.47	0.23–0.95	0.034
Variable	IRR	CI 95%	P-value
Number of Days Febrile
HRV by SDNN, msec	0.97	0.94–0.99	0.015
Initial Graeb Score	1.11	1.06–1.16	< 0.001
Ventilator Free Days	0.91	0.88–0.94	< 0.001
Pneumonia	2.28	1.49–3.49	< 0.001
History of Hypertension	0.71	0.50–1.03	0.069
Initial Hematoma Volume	1.01	1.00–1.02	0.007
RMSSD (Secondary HRV Metric)
Variable	OR	CI 95%	P-value
Occurrence of Fever
HRV by RMSSD, msec	0.958	0.921–0.996	0.030
Initial Graeb Score	1.17	1.04–1.32	0.010
Ventilator Free Days	0.90	0.84–0.97	0.003
Pneumonia	10.5	2.29–47.6	0.002
History of Hypertension	0.44	0.22–0.88	0.020
Initial Hematoma Volume	1.02	1.00–1.04	0.037
Variable	IRR	CI 95%	P-value
Number of Days Febrile
HRV by RMSSD, msec	0.978	0.957–0.999	0.040
Initial Graeb Score	1.11	1.06–1.17	< 0.001
Ventilator Free Days	0.91	0.88–0.94	< 0.001
Pneumonia	2.22	1.45–3.39	< 0.001
History of Hypertension	0.73	0.51–1.05	0.087
Initial Hematoma Volume	1.01	1.00–1.02	0.003

Variables assessed for parsimonious model inclusion included: age, heart rate variability (SDNN and RMSSD), admission Glasgow Coma Scale score, initial Graeb score, initial hematoma volume, days free of mechanical ventilation, diagnosis of pneumonia during hospitalization, lobar hematoma location, history of hypertension, and beta blocker exposure.

CI = confidence interval, GCS = Glasgow Coma Scale, HRV = heart rate variability, IRR = incidence rate ratio, OR = odds ratio, RMSSD = root mean square of successive R-R interval differences, SDNN = standard deviation of the R-R interval.