anchor.diff:  "72","Perforation of colon"
   "73","COPD"
   "79","Multi-system failure"
  -"81","Accident related to ERF treatment (not 25)"
  +"81","Accident related to ESRF treatment (not 25)"
   "82","Accident unrelated to ERF treatment"
   "99","Other identified cause of death"
   "100","Peritonitis (bacterial, with peritoneal dialysis)"
  
positive.code: "code","cause"
  "0","Cause of death uncertain/not determined"
  "11","Myocardial ischaemia and infarction"
  "12","Hyperkalaemia"
  "13","Haemorrhagic pericarditis"
  
negative.code: "104","Calciphylaxis"
  "105","Ischaemic bowel"
  "106","Ruptured AAA"
  "107","Advanced CKD not on dialysis(conservative management)"
  "108","Acute kidney injury"
  "109","C Diff colitis"
  "110","Line related sepsis"
  