. 2016 May 19;11(5):e0154970. doi: 10.1371/journal.pone.0154970

Table 2. Characteristics of included patients according to RT-PCR result.

	Influenza negative		Influenza positive		A(H3N2)^a		A(H1N1)p^a		B/Yamagata^a
	N = 4217		N = 1086		N = 534		N = 362		N = 130
Characteristic	n	%	n	%	n	%	n	%	n	%
Age in years, mean (standard deviation)	30.9 (31.7)		34.9 (28.6)		30 (27.0)		45.8^* (29.3)		30.6 (25.6)
Age group
0–5 months	503	11.9	54	5	22	4.1	21	5.8	3	2.3
6–11 months	279	6.6	36	3.3	20	3.7	11	3	1	0.8
1–4 years	905	21.5	181	16.7	100	18.7	44	12.2	23	17.7
5–17 years	291	6.9	102	9.4	57	10.7	14	3.9	24	18.5
18–49 years	929	22.0	349	32.1	214	40.1	70	19.4	49	37.7
50–64 years	337	8.0	132	12.2	29	5.4	87	24.1	11	8.5
65–74 years	304	7.2	94	8.7	32	6.0	51	14.1	8	6.2
75–84 years	426	10.1	106	9.8	47	8.8	47	13	9	6.9
≥85 y	243	5.8	32	2.9	13	2.4	16	4.4	2	1.5
Female	1829	43.4	547	50.4^*	284	53.2^*	165	45.7	72	55.4^*
Number of underlying comorbidities
0	2789	66.1	656	60.4	345	64.6	165	45.7	94	72.3
1	732	17.4	260	23.9^*	122	22.8^*	109	30.2^*	24	18.5
≥2	696	16.5	170	15.7	67	12.5	87	24.1^*	12	9.2
Underlying chronic diseases
Cardiovascular disease	685	17.1	189	18.4	91	17.9	80	22.8^*	13	12.3
COPD	607	15.2	139	13.6	44	8.7^*	79	22.5^*	13	12.3
Asthma	194	4.8	76	7.4^*	35	6.9	31	8.8^*	10	9.4
Immunodeficiency/organ transplant	38	0.9	16	1.6	13	2.6^*	3	0.9	0	0
Diabetes	390	9.7	105	10.2	30	5.9^*	67	19.1^*	5	4.7
Chronic renal impairment	167	4.2	57	5.6	24	4.7	28	8^*	4	3.8
Chronic rheumatologic disease	12	0.5	11	1.7^*	6	1.4	1	1.8	4	3.8^*
Chronic neuromuscular disease	94	2.3	19	1.9	14	2.8	3	0.9^*	2	1.9
Active neoplasm	130	3.2	29	2.8	13	2.6	15	4.3	0	0
Chronic liver disease	65	1.6	23	2.2	10	2.0	11	3.1	1	0.9
Autoimmune disease	32	0.8	16	1.6^*	8	1.6	6	1.7	2	1.9
Pregnant status (women 15–45 years)	181	44.7	156	70.3^*	100	71.9^*	18	51.4.	33	86.8^*
Obese^b	701	16.9	194	18.1	77	14.6	95	26.5^*	14	10.9
Outpatient visits in the last 3 months^c
0	1283	30.5	306	28.2	172	32.2	85	23.6	30	23.1
1	919	21.8	241	22.2	93	17.4	112	31.1	19	14.6
≥2	2011	47.7	538	49.6	269	50.4	163	45.3	81	62.3^*
Smoking habits^d
Current smoker	1009	23.9	274	25.3	124	23.2	100	27.7	31	24
Past smoker	813	19.3	200	18.4	96	18.0	75	20.8	24	18.6
Never smoked	2392	56.8	611	56.3	314	58.8	186	51.5	74	57.4
Functional index (Barthel)^e
Total or severe dependence	106	11.1	14	6.4	4	4.9	10	8.8	0	0
Moderate-mild dependence	294	30.9	63	28.6	29	35.4	21	18.4	11	64.7^*
No dependence	552	58.0	143	65.0^*	49	59.8	83	72.8^*	6	35.3
Days from onset of symptoms to swabbing
0–2 days	1569	37.2	465	42.8	261	48.9	128	35.5	47	36.2
3–4 days	1595	37.8	418	38.5	199	37.3	141	39.1	58	44.6
5–7 days	1053	25.0	203	18.7^*	74	13.9^*	92	25.5	25	19.2
Influenza vaccination ≥14 d from ILI onset	714	16.9	138	12.7^*	46	8.6^*	84	23.3^*	5	3.8^*

^a Comparison group, negative influenza admissions

^b Obesity was defined as a body mass index ≥30 for subjects ≥18 years of age and as a z-score of body mass index for age >2 standard deviations for subjects <18 years of age. Data were missing for 79 influenza-negative patients and 12 influenza-positive patients.

^c Data were missing for 4 influenza-negative patients and 1 influenza-positive patient.

^d Data were missing for 3 influenza negative patients and 1 influenza-positive patient.

^e Assessed for admissions ≥65 years of age. Data were missing for 21 influenza-negative patients and 12 influenza-positive patients.

*P<0.05 vs. influenza negative