Hylke Salverda

141 8 Clinical outcomes comparison of two different AOCs Data collection and outcome measures Patient records are kept digitally in our patient data management system (Metavision; IMDsoft, Tel Aviv, Israel). The followingoutcomeswerenoted fromeither these records or from the discharge papers from the regional hospital where the infant resided before being discharged home: mortality until one month after corrected term age, ROP, BPD, necrotising enterocolitis (NEC), culture proven sepsis, intraventricular haemorrhage (IVH), periventricular leukomalacia (PVL), and length of NICU stay. The duration of respiratory therapy and supplemental oxygen (measured FiO2 above 0.21) and the mean of inspiratory oxygen during the first week and entire admission were calculated from our patient data management system which routinely samples clinical parameters and ventilator settings once per minute. High flow nasal cannula (HFNC) was available in SLE6000, not in AVEA. The device we used for HFNC during the CLiO2 period did not allow for automatic data storage or for automated oxygen titration. Therefore to minimise biased results, the duration of supplemental oxygen therapy was analysed both with and without periods of HFNC. The ophthalmologists in our hospital implemented the Early Treatment of Retinopathy of Prematurity study (ETROP) classification for findings of retinal examination in 2013 and ROP was defined according to this classification.14, 15 Laser coagulation for treatment of severe ROP is first choice, anti-VEGF injections are not standard of care. When retinal findings were described otherwise, researcher HHS classified according to the ETROP criteria retrospectively, assisted by an ophthalmologist where necessary. An assessment for BPD was made at 36 weeks postmenstrual age classified as either none, mild, moderate-severe according to adapted criteria from the 2000-NICHD consensus. 16 We chose to combine the moderate and severe classifications as discharge papers fromregional hospitals sometimes did not indicate which respiratory therapy was applied at what time. NEC was defined according to the modified Bell staging criteria17, IVH was classified according to Papile’s adapted classification 18, 19, PVL according to the de Vries’ classification. 20 Analysis Data are presented as mean (SD), median [IQR] or (range), or number (percentage) as appropriate. Standard tests for normality (visual assessment, KolmogorovSmirnov, Shapiro-Wilk) were done. Statistical comparison was performed using a related-samples Wilcoxon signed rank test with Hodges-Lehman median difference confidence interval or related-samples McNemar test as appropriate. Outcomes with more than 2 categories were analysed using a Bhapkar test.21 Risk ratios and confidence intervals were calculated according to the method described by Algresti