Table 3.

Multiple logistic regression analysis showing associations between duration of hospitalisation (in days) and other variables, for all patients (n = 306).

Variable	Ratio	95% CI		p Value
Ct valuea	0.94	0.92	0.97	<0.001
Agea	1.02	1.01	1.04	<0.001
Duration of illness prior to admission, days	0.99	0.93	1.07	0.965
Sex (reference group: female)	0.80	0.58	1.11	0.181
Influenza vaccine (reference group: no)	0.94	0.67	1.31	0.700
Comorbidity (reference group: none)	1.47	1.05	2.07	0.025
Antibiotics prior to admission (reference group: none)	1.12	0.78	1.60	0.544
Current smoker (reference group: no)	1.11	0.78	1.58	0.563
Bacterial detection (reference group: no)	1.78	1.18	2.67	0.006
Clinical group
Asthma (reference group)	–	–	–	–
IECOPD	1.16	0.72	1.85	0.538
Pneumonia	1.44	0.79	2.63	0.236
ILI/bronchitis	0.46	0.21	0.98	0.044
Virus type
Influenza (reference group)	–	–	–	–
Rhino/enterovirus	0.92	0.62	1.38	0.692
Other virusesb	1.12	0.74	1.70	0.588

Abbreviations: Ct, real-time PCR Cycle threshold (a low Ct value represents a high viral load and vice versa); IECOPD, infective exacerbation of COPD; CAP, community acquired pneumonia; ILI, Influenza-like illness; CI, confidence interval.

Note: For each unit decrease in Ct value (i.e. increase in viral load), there is a 6% increase in expected days in hospital. Likewise, for each additional year of age, length of stay increases by 2%. The presence of at least one of any recorded comorbidity (cardiovascular, renal or liver disease, malignancy or diabetes) increases length of stay by 47% relative to people without any of these comorbidities. The detection of bacteria was associated with a 78% increase in length of stay. Patients with ILI/bronchitis had a length of stay 46% shorter than those with asthma.

p values highlighted in bold are statistically significant (i.e., p <0.05).

^aVariables are mean-centred.

^bIncludes; Respiratory Syncytial Virus, parainfluenza 1–4, human metapneumovirus, human coronavirus and adenovirus.