S24 Predicting poor outcome at six months following exacerbations of COPD requiring assisted ventilation

IntroductionNon-invasive ventilation (NIV) is life-saving in exacerbations of COPD complicated by acute hypercapnic respiratory failure (AHRF). These episodes indicate advanced disease and patients who survive the acute episode show significant morbidity and high one-year mortality.1 In this group, clinicians can be prognostically pessimistic about outcome and quality of life (QoL); understanding predictors of poor outcome six months following an episode of AHRF treated with NIV could help clinical decision making.MethodsUnique, consecutive patients were prospectively recruited to the NIV Outcomes study (ISRCTN22921168) in 10 NHS trusts. Consenting patients surviving to discharge were followed up monthly with QoL assessed using validated QoL questionnaires including the COPD Assessment Test (CAT). Poor outcome was defined as a pre-discharge CAT score in the worst 50% of responses (CAT=24–40) with subsequent clinically significant decline (≥2 points), or death, within six months. Multivariate logistic regression identified independent predictors. Continuous variables were subsequently dichotomised, and regression rerun.Results553 patients survived to discharge; 253 consented and 239 provided >1 QoL assessment. Median(IQR) follow up time was 359(171–367) days, with 8(3–11) months of questionnaires completed, and NIVO score of 3(1–3.75). Mean(SD) age 68.9(9.1) years and FEV136.8(14.7)% predicted. 34.2% had previously received NIV, 24.6% were prescribed LTOT, and 47.1% were unable to leave the house unassisted. 56.6% had persistent hypercapnia post-ventilation. 67/239 suffered poor outcome.Independent predictors of poor outcome were LTOT, Left Ventricular Systolic Dysfunction, Diaphragm height ≤2.3 cm, confusion pre-ventilation, admission haemoglobin ≤14 g/dL, Pre-discharge HADS-depression Score ≥8, Pre-discharge Nottingham Extended Activities of Daily Living score ≤30 (Table 1). A simple tool (1 point assigned to each variable) demonstrated an area under the receiver operating characteristic curve of 0.809 (95% CI’s: 0.747–0.871).Abstract S24 Table 1Result of backwards stepwise regression model showing independent predictors of poor outcome VARIABLE B S.E Wald P value Odds Ratio (95% CI ) Long term oxygen therapy 1.069.3698.412.0042.913 (1.414–5.999) Left ventricular systolic dysfunction 1.017.4255.721.0172.764 (1.201–6.358) Diaphragm height ≤ 2.3 cm .730.3414.571.0332.074 (1.063–4.048) Confusion pre ventilation 1.045.4246.072.0142.843 (1.238–6.525) Haemoglob