Influenza A H1N1 Community-Acquired Pneumonia: Characteristics and Risk Factors—A Case-Control Study

Table 2

Factors related with hospitalization and mortality.

Variable	H1N1 cases (n, %)	Controls (n, %)	value
Admission to the intensive care unit			<0.01
No	58 (58.5)	251 (93.0)
Yes	41 (41.5)	19 (7.0)
Length of stay at intensive care unit (days)			<0.01
Median	14	3
Percentile 25–75	8–24.5	2–7
Needed invasive ventilation			<0.01
No	63 (63.6)	256 (95.2)
Yes	36 (26.4)	13 (4.8)
Length of hospital stay (days)			<0.01
Median	10	7
Percentile 25–75	7–19	5–9
In-hospital mortality	13 (13)	0 (0)	<0.01
Mortality following hospital discharge (<30 days)	0 (0)	1 (0.3)	<0.01
Leukocytes (cell/mm^3)			<0.01
Median	6,560	12,250
Percentile 25–75	4,230–9,540	8,077–18,577
Neutrophils (cell/mm^3)			<0.01
Median	5,300	9,900
Percentile 25–75	6,307.5–15,685	2,910–7,980
Lymphocytes (cell/mm^3)			<0.01
Median	700	810
Percentile 25–75	430–1,200	600–1,267.5
Monocytes (cell/mm^3)			<0.01
Median	300	590
Percentile 25–75	110–540	380–800
AST (IU/L)			<0.01
Median	45	21
Percentile 25–75	24.5–103.5	15–37
Arthromyalgia			<0.01
No	62 (62.6)	235 (87.3)
Yes	37 (37.4)	34 (12.7)
Chest X-ray presentation			<0.01
Lobar	37 (37.4)	205 (75.9)
Bilobar	1 (1.0)	25 (9.3)
Bilateral	61 (61.6)	40 (14.8)
Radiological pattern			<0.01
Alveolar	76 (76.8)	235 (87.0)
Interstitial	8 (8.1)	2 (0.7)
Alveolointerstitial	10 (10.1)	30 (11.1)
Patchy radiological involvement	5 (5.0)	3 (1.1)

ALT: alanine aminotransferase; AST: aspartate aminotransferase; CURB65: pneumonia severity score calculator 65; GGT: gamma-glutamyl transpeptidase; PSI score: pneumonia severity index score; pO₂: O₂ partial pressure. Obtained for cases admitted at ICU.