Table 2.

Patient Characteristics According to Quartiles of RS Initial NIV

Characteristic	Quartiles of Hospital RS Initial NIVa				P Value for Trend
Quartile 1	Quartile 2	Quartile 3	Quartile 4
Age (median, IQR), y	56 [54-58]	54 [51-60]	53 [49-55]	55 [51-58]	.23
Female	74 [70-76]	74 [69-78]	73 [68-75]	74 [72-76]	.87
Black	13 [6-43]	24 [12-45]	18 [5-55]	13 [4-30]	.67
Patients with no admissions at 1 y	68 [66-71]	74 [67-78]	67 [62-74]	69 [62-70]	.50
Congestive heart failure	15 [11-16]	12 [4-13]	9 [6-11]	12 [7-15]	.07
Valvular disease	4 [3-5]	3 [2-5]	3 [2-4]	3 [2-6]	.64
Peripheral vascular disease	3 [1-3]	2 [1-4]	2 [1-3]	2 [1-3]	.33
Neurologic disorders	6 [4-7]	6 [3-8]	5 [3-7]	5 [4-7]	.43
Chronic pulmonary disease	13 [8-16]	10 [5-19]	8 [5-13]	13 [9-17]	.79
Diabetes with no chronic complications	23 [20-29]	22 [20-26]	21 [19-22]	20 [15-23]	.07
Renal failure	6 [5-7]	7 [2-9]	4 [3-5]	7 [1-8]	.27
Obesity	16 [13-22]	17 [11-22]	17 [12-20]	17 [13-22]	.86
Deficiency anemia	11 [8-15]	9 [4-11]	8 [5-9]	10 [8-13]	.38
Depression	10 [5-18]	12 [3-17]	15 [9-18]	9 [8-23]	.58
Hypertension	45 [34-56]	47 [32-56]	44 [34-54]	45 [26-56]	.59
Prior IMV within 12 mo	2 [1-4]	1 [0-2]	4 [0-5]	2 [1-5]	.96
Prior NIV within 12 mo	0 [0-0]	0 [0-1]	3 [2-6]	5 [4-7]	< .001
Pneumonia present on admission	11 [9-15]	11 [6-13]	9 [7-14]	8 [6-10]	.07
LAPS	30 [29-31]	30 [28-33]	30 [29-32]	32 [29-34]	.13
pH	7.36 [7.34-7.37]	7.38 [7.32-7.38]	7.36 [7.33-7.40]	7.37 [7.34-7.39]	.57
Paco2, mm Hg	46 [44-52]	46 [44-53]	46 [44-49]	49 [44-51]	.98
Pao2, mm Hg	133 [106-161]	122 [109-128]	128 [114-183]	132 [108-148]	.89
Oxygen saturation, %	96 [96-98]	97 [96-97]	96 [95-97]	96 [95-97]	.05
Prior IMV within 12 mo	2 [1-4]	1 [0-2]	4 [0-5]	2 [1-5]	.96
Prior NIV within 12 mo	0 [0-0]	0 [0-1]	3 [2-6]	5 [4-7]	< .001
Admission to ICU	5 [1-11]	4 [1-8]	6 [0-11]	5 [0-11]	.74
Admission to ICU or step-down unit	7 [1-11]	4 [1-8]	6 [0-17]	5 [0-16]	.75

Numbers in each row express the median and IQR. LAPS = Laboratory-based Acute Physiology Score. See Table 1 legend for expansion of other abbreviations.

^aRefers to the first method of ventilation during hospitalization.