A Study of Ulcerative Colitis in New Zealand, Showing a Low Incidence in Maoris

Abstract

As no population study of non-specific ulcerative colitis has yet been completed, the incidence of this disease in the community is not known. Hospital in-patient records and national mortality statistics provide the only information available, but it is not usually possible to define the population from which hospital cases are drawn. Weiner and Lewis (1960) have summarized the published hospital data. Melrose's (1955) finding that colitis was more common in England than in Scotland has not been borne out by subsequent statistics. Jones (1956) noted a higher admission rate in the north eastern part of the United States than in the south, comparing the number of colitis patients admitted with the total number of admissions. Acheson (1959), studying the mortality of this disease in the United States, Canada, and England and Wales, found rather higher death rates in England and Wales than in the U.S.A. or Canada. The rate was higher in north-east and central U.S.A. than in the south. The urban rate was higher than the rural rate and there was a negative correlation with the distribution of dysentery. Acheson (1960), using the Veterans Administration Hospital statistics, was able to confirm Paulley's (1950) finding that colitis is more common in Jews. There is some evidence that colitis is less common in North-American negroes (Weiner and Lewis, 1960), but Acheson (1960) was unable to find convincing evidence of this from the Veterans Administration figures. The disease is said to be very rare in the North-American Indian (Bebchuk et al., 1961) and in negro children in the U.S.A. (Reinhart, 1961). The familial incidence of colitis has been variously reported from 1 to 17%, and there have been two reports of the disease affecting identical twins (Feder, 1938 ; Lyons and Postlethwait, 1948). Houghton and Naish (1958) described two families with three cases, and possibly four in one of them. They thought that this incidence was greater than could occur by chance, but McConnell (1960) thinks that the general incidence of colitis may have been underestimated. The present findings suggest that the incidence was overestimated. All the reported familial cases were blood relations, chiefly siblings, except for two married couples noted by Felsen and Wolarsky (1955) and another couple treated by J. B. W. Dunlop (1960, personal communication). As New Zealand is a relatively closed community with a state medical service and all hospital discharge diagnoses have been filed under the international code since 1949, it is felt that useful information might be gained from a study of this material. We are indebted to Messrs. R. J. Rose and F. H. Foster, of the medical statistics branch at the Department of Health, New Zealand, for providing the relevant data.