Table 2.: Patient Characteristics and Possible Risk Factors (Influenza Vaccination Status, Exposure to Oseltamivir, and Underlying Illnesses) by Source of the Sample and by Oseltamivir Susceptibility of the A(H1N1) Virus

Baseline Characteristics Sentinel Non-Sentinel
Resistant n=14 Sensitive n=57 OR (95%BI) Resistant n=32 Sensitive n=68 OR (95%BI)
Age in years:
median, range 25 (0.7 - 43) 27 (0.8 – 65) NA 0.8 (0.3 -22) 0.9 (0.1 – 67) NA
Sex (%man) 6/14 (43%) 28/57 (49%) 0.8 (0.2 - 2.5) 15/32 (47%) 29/58 (50%) 0.9 (0.4 – 2.1)
Province (NH+ZH) 11/14 (78.6%) 17/57 (29.8%) 8.6 (2.1 – 34.9) No province associated distribution
Vaccinated 1/14 (7.1%) 2/57 (3.5%) 2.1 (0.2 – 25.2) 1/18 (5.6%) 2/27 (7.4%) 0.7 (0.1 – 8.8)
Travelled abroad 0/14 2/54 (3.7%) NA 0/17 0/21 NA
Oseltamivir use patienta 0/14 1/57 (1.7%) NA 0/20 0/28 NA
Oseltamivir use contacta 0/13 0/57 NA 0/20 1/23 (4.4%) NA
Respiratory allergyb 0/14 2/57 (3.5%) NA 1/17 (5.9%) 1/28 (3.6%) 1.7 (0.1 – 28.9)
Immunocompromised 0/14 0/57 NA 4/20 (20.0%) 2/28 (7.1%) 3.3 (0.5 -19.8)
Chronic disease 1/14 (7.1%) 4/57 (7.0%) 1.0 (0.1 – 9.9) 5/20 (25.0%) 7/28 (25.0%) 1.0 (0.3 – 3.8)

a within 14 days after first day of illness.
b respiratory allergy is the clinical presentation, in particular rhinitis, asthma and COPD, resulting from an allergic reaction of the respiratory tract following inhalation of a (bio)chemical allergen.
OR= odds ratio; NA = not available; NH+ZH = Noord- and Zuid-Holland;
'p>0.05 for all differences in course and severity between patients with a resistant virus and patients with a sensitive virus and age in 2 categories (17 years and younger and 18 years en older).