Table 2

Main prognostic factors for length of stay of 8 days or more from admission in 1362 patients

No of patientsNo staying 8+ days% staying 8+ daysRelative risk95% CI
FEV1=forced expiratory volume in 1 second; PEF=peak expiratory flow; Sao2=oxygen saturation; IPPV=invasive positive pressure ventilation; NIPPV=non-invasive positive pressure ventilation; NK=not known. *Lower, middle and upper thirds of FEV1 values in litres derived separately for men (lower ≤0.75, middle 0.76–1.16, upper >1.6) and women (lower ≤0.60, middle 0.61–0.89, upper >0.89).
Background and history:
Age
    <6528210336.51.0
    65–692149443.91.21.0 to 1.5
    70–7431816852.81.41.2 to 1.7
    75–7927915957.01.61.3 to 1.9
    80+26415960.21.71.4 to 2.0
    NK52
FEV1 tertiles*
    Lower third24214660.31.51.3 to 1.9
    Middle third22111250.71.31.1 to 1.6
    Upper third2369339.41.0
    NK66333450.4
Performance status
    Normal activity1063734.91.0
    Strenuous activity limited1456544.81.30.9 to 1.8
    Limited but self-care42420849.11.41.1 to 1.9
    Limited self-care36422261.01.81.3 to 2.3
    Bed care, no self-care392666.71.91.4 to 2.7
    NK28412744.7
Assessment and measurements on admission:
Admission PEF (l/min)
    Not done66537756.71.81.4 to 2.2
    Unrecordable1126053.61.71.3 to 2.2
    ≤15033815746.41.41.1 to 1.8
    >1501805832.21.0
    NK673349.3
Sao2 (%)
    <8617011265.91.41.2 to 1.6
    86–9226413350.41.10.9 to 1.2
    >9258928147.71.0
    NK33915946.9
Initial management (within first 24 hours)
IPPV or NIPPV
    Yes403382.51.71.4 to 2.0
    No132265249.31.0