Table 2. Distribution of influenza cases and controls aged ≥ 65 years according to comorbidities, Spain, influenza seasons 2013/14 and 2014/15.

Characteristics	Cases (n = 728)		Controls (n = 1,826)		Crude OR	95% CI	p value
	n	%	n	%
High-risk medical conditions
COPD	194	26.6	218	11.9	3.03	2.37–3.88	< 0.001
Chronic respiratory failure	119	16.3	208	11.4	1.64	1.26–2.14	< 0.001
Pneumonia past 2 years	91	12.5	104	5.7	2.40	1.77–3.26	< 0.001
Other lung disease	238	32.7	380	20.8	1.88	1.54–2.30	< 0.001
Cardiovascular disease	224	30.8	651	35.7	0.84	0.68–1.03	0.09
Diabetes mellitus	235	32.3	666	36.5	0.89	0.74–1.07	0.21
Renal failure with hemodialysis	16	2.2	31	1.7	1.27	0.68–2.37	0.46
Hemaglobinopathy or anaemia	89	12.2	306	16.8	0.68	0.52–0.88	0.004
AIDS	1	0.1	2	0.1	1.30	0.12–14.51	0.83
Asymptomatic HIV infection	3	0.4	1	0.1	9.00	0.94–86.52	0.06
Neurological disease	51	7.0	136	7.4	0.93	0.64–1.33	0.93
Obesity (BMI  ≥ 30 kg/m2)	174	23.9	370	20.3	1.25	1.01–1.56	0.04
Non high-risk medical conditions
Solid organ neoplasia	103	14.1	348	19.1	0.67	0.52–0.85	0.001
Haematologic neoplasia	39	5.4	40	2.2	2.57	1.62–4.07	< 0.001
Transplantation	22	3.0	10	0.5	5.52	2.52–12.09	< 0.001
Immunosuppressive treatment	35	4.8	67	3.7	1.35	0.87–2.08	0.18
Oral corticosteroid therapy	44	6.0	43	2.4	2.54	1.62–3.97	< 0.001
Asplenia	2	0.3	8	0.4	0.66	0.14–3.11	0.60
Renal failure without hemodialysis	135	18.5	341	18.7	1.01	0.80–1.26	0.94
Nephrotic syndrome	7	1.0	14	0.8	1.14	0.45–2.88	0.78
Autoimmune disease	47	6.5	96	5.3	1.38	0.94–2.03	0.10
Chronic liver disease	28	3.8	95	5.2	0.76	0.49–1.18	0.22
Cognitive dysfunction	76	10.4	205	11.2	0.92	0.68–1.23	0.92
Neuromuscular disease	24	3.3	53	2.9	1.16	0.70–1.93	0.55
Convulsions	8	1.1	23	1.3	0.84	0.37–1.92	0.69

BMI: body mass index; CI: confidence interval; COPD: chronic obstructive pulmonary disease; OR: odds ratio.