Variations in operation rates in New Zealand.

The standardised rates of nine common operations in the seven largest hospital boards in New Zealand varies markedly with the ratio of highest/lowest ranging from 1.2 for cholecystectomy to 2.9 for tonsillectomy. There were also marked variations between New Zealand, Scotland, USA and England and Wales with the ratio of high/low ranging from 1.2 for appendicectomy to 4.5 for haemorrhoidectomy. The New Zealand rates tended to be higher than the English but lower than the USA rates. Several operation rates were correlated with the size of waiting lists but there were no other consistent relationships with any of the other variables studied - hospital board funding, percentage of operations performed in private hospitals, and rates of general practitioners, specialist surgeons, and acute surgical beds in public hospitals per 100,000 population.