Evaluating non-randomised intervention studies - NIHR Health ...

74TABLE 26 Comparison of methods of case-mix adjustment applied to results of historically controlled studies with results of RCTs resampled from 14 regions within the IST, analysed by regionHistorically controlled studiesRCTs Unadjusted Logistic regression a Stratified Propensity score b% over or % over % over Average % overAverage Average or under Average or under Average or under OR or underOR OR estimate OR estimate OR estimate estimateScotland 0.78 1.23 +58 1.40 +79 1.48 +90 1.30 +67Southern Italy 0.56 1.00 +79 0.98 +75 0.89 +59 0.97 +73Northern Italy 0.94 1.15 +22 1.06 +13 1.20 +28 1.05 +12New Zealand 0.81 0.97 +20 0.94 +16 1.09 +35 1.08 +33Australia 1.30 1.39 +7 1.09 –16 1.49 +15 1.08 –17Switzerland 0.97 1.07 +10 1.05 +8 1.13 +16 1.04 +7Central Italy 0.89 0.92 +3 0.85 –4 0.89 0 0.87 –2The Netherlands 0.88 0.85 –3 1.14 +30 1.11 +26 1.10 +25Northern England 0.95 0.92 –3 0.79 –17 1.03 +8 0.86 –9Spain 1.00 0.93 –7 0.59 –41 0.57 –43 0.75 –25Southern England 1.01 0.87 –14 0.72 –29 0.85 –16 0.81 –20Poland 0.91 0.70 –23 1.08 +19 0.69 –24 1.06 +16Norway 0.78 0.48 –38 0.41 –47 0.47 –40 0.51 –35Sweden 0.94 0.44 –53 0.47 –50 0.37 –61 0.58 –38a Logistic regression was performed using the full model with 10 covariates.b Propensity scores were used in a regression adjustment.Empirical evaluation of the ability of case-mix adjustment methodologies to control for selection bias