Roy Lay Yee

Differences in intake of specific food plants by Polynesians may explain their lower incidence of colorectal cancer compared with Europeans in New Zealand

Epidemiological studies have implicated obesity; high intakes of alcohol, fat, and energy; and low intakes of food plants as risk factors for colorectal cancer. In New Zealand, Polynesians (including Maoris and people from several Pacific Islands) are more likely to be overweight and have higher intakes of fat and energy than Europeans, and they are likely to have similar total intakes of food plants. Yet, in New Zealand, Polynesians have a significantly lower incidence of colorectal cancer than the Europeans. It is possible that the difference in incidence of colorectal cancer is due to differences in consumption of specific food plants by Polynesians and Europeans in New Zealand. Here we have compared the consumption of specific food plants by 429 Maoris, 643 Pacific Islanders, and 4,451 Europeans in paid employment in New Zealand. Of the 51 food plants eaten by New Zealanders, 6 were eaten significantly more frequently and 17 significantly less frequently by the two Polynesian groups than by Europeans. The quantity of any protective chemical components (or other as yet unknown protective factors) in food plants is likely to be related to their botanical classification. Differences in the intake of specific food plants may at least partly explain differences in the incidence of colorectal cancer between Polynesians and Europeans.

The New Zealand Partner Relations Survey: methodological results of a national telephone survey.

ObjectiveTo implement and evaluate a national survey of sexual behaviour using computer-assisted telephone interviewing (CATI). DesignA two-stage stratified national sample survey in which households were selected by random digit-dialling (RDD), with a single eligible interviewee per selected household, followed by subsample surveys of non-contacts and refusals to determine eligibility. MethodsA 15-minute questionnaire based on the Global Programme on AIDS (GPA)/World Health Organization (WHO) protocol was administered by telephone to a nationally representative sample of 2361 respondents in the 18–54-year age group. ResultsThe overall response rate was 63%, but lower in the cities, in the 18–24 age group, and among men. Three-quarters of surveyed non-contacts, and a quarter of resurveyed refusals, did not meet the eligibility criteria for the study. Less than 20% of refusals cited the subject matter of the survey as the reason for refusal. Item non-response (< 1%) increased with question sensitivity, and varied by respondent age, ethnicity and partnership status. Men reported twice as many adult lifetime partners as women. ConclusionsThe GPA/WHO protocol can be successfully adapted to administration by telephone, with adequate response rates and exceptionally low levels of item non-response. CATI is a cost-effective method for collecting national information on sexual behaviour in countries where there is a high level of telephone ownership. Used in conjunction with RDD, it can overcome problems of sample design in settings where there is no comprehensive population-sampling frame. Checks on item sensitivity and partner estimates suggest that acceptable levels of reliability can also be achieved.