group morphine chronic 31.5 chronic 35.1 chronic 32.1 chronic 34.2 chronic 26.7 chronic 31.9 chronic 30.8 chronic 27.3 chronic 27.3 chronic 29.0 chronic 30.0 chronic 36.4 chronic 39.8 chronic 32.0 acute 31.6 acute 28.5 dialysis 29.3 dialysis 32.1 dialysis 26.9 anephric 26.5 anephric 22.7 anephric 27.5 anephric 24.9 anephric 23.4