Table 4

Analysis of comorbidity, demography, clinical characteristics and selected investigations as risk factors for severe outcome in patients hospitalised with pandemic H1N1 infection during the first pandemic wave

People affected by condition or feature (number with severe outcome)Likelihood ratio (95% CI)p Value
Age (years)1.01* (0.99 to 1.02)0.089
Asthma159 (18)0.77 (0.44 to 1.34)0.360
COPD25 (6)2.10 (0.81 to 5.43)0.123
Chronic pulmonary conditions, excluding asthma or COPD21 (7)3.41 (1.33 to 8.71)0.010
Cardiovascular disease69 (12)1.41 (0.72 to 2.75)0.314
Diabetes51 (7)1.02 (0.44 to 2.35)0.956
Neurological disorders19 (3)1.21 (0.34 to 4.25)0.764
Hepatic disease7 (2)2.60 (0.49 to 13.65)0.257
Obesity recorded on admission8 (4)6.96 (1.46 to 27.28)0.008
Smoker (current and former)103 (16)1.01 (0.53 to 1.91)0.972
Pregnancy27 (6)1.87 (0.73 to 4.77)0.190
White ethnicity 202 (29)1.08 (0.65 to 1.78)0.764
Altered conscious level10 (6)1.11 (1.04 to 1.17)0.001
Dyspnoea181 (44)1.32 (1.81 to 1.49)0.001
Heart rate (abnormal)198 (31)1.62 (0.80 to 3.30)0.180
Respiratory rate (abnormal)89 (16)1.78 (0.89 to 3.56)0.102
Required supplemental oxygen on admission99 (33)4.51 (2.72 to 7.40)0.001
Intravenous fluid replacement on admission145 (28)1.76 (1.07 to 2.89)0.005
Radiologically-confirmed pneumonia102 (37)5.28 (2.95 to 9.47)0.001
CRP ≥100 mg/l46 (16)4.41 (2.14 to 9.10)0.001
Spo2 <94% on air107 (31)3.60 (2.17 to 6.27)0.001
  • * Reflects a 1% increase in risk of severe outcome for each additional year of age.

  • Information about smoking history was documented for 216 cases; ethnicity was recorded for 537 cases; heart rate, with corrections for temperature, was available for 512 cases; respiratory rate was recorded for 470 cases; chest radiography findings were recorded for 349 cases; CRP levels were recorded for 306 cases; Spo2 data were recorded for 252 cases.

  • 45 severe outcomes among 335 non-white patients.

  • COPD, chronic obstructive pulmonary disease; CRP, C-reactive protein; Spo2, peripheral oxygen saturation.