Eleven procedures, representing a variety of conditions and which were commonly performed, were studied. The following diagnostic limitations were applied:
Cholecystectomy (removal of gallbladder): excluded patients who had surgery for malignancies or pancreatitis. The main diagnoses included were gallstones, cholecystitis or abdominal pain.
Hernia repair: included inguinal and femoral hernia without gangrene
Excision of breast lesions: diagnostic codes included benign and malignant tumours of the breast, lumpectomies and mastectomies. Breast biopsies were excluded.
Stripping/Ligation of Varicose Veins: Only lower extremities, not oesophageal or gastric
Carpal Tunnel Release: for carpal tunnel syndrome
Transurethral Prostatectomy (TURP): for benign hyperplasia. Excluded all malignancies.
Tonsillectomy: For tonsillitis of hypertrophy: not for middle ear infections.
Carotid endarterectomy: no diagnostic restrictions
Cataract extraction: no diagnostic restrictions
Coronary artery bypass: no diagnostic restrictions
Percutaneous transluminal coronary angioplasty: no diagnostic limitations