OBJECTIVE: To facilitate the quantitative comparison of AIDS incidence statistics between countries and with other diseases using statistics based on age-standardized incidence rates instead of absolute number of cases. DESIGN: AIDS incidence rates for 19 countries belonging to the World Health Organization (WHO) European region, and for comparative purposes, the United States. METHODS: Incidence rates were standardized using the world standard population for all ages, from 1985 to 1992. The data were derived from the WHO European Non-Aggregate AIDS Dataset and the Centers for Disease Control and Prevention (CDC) AIDS Public Information Dataset, adjusted for reporting delays in each country. RESULTS: The AIDS incidence rate for men (81 in 1,000,000) in the United States was fourfold higher than the highest rate in a European country (Switzerland) in 1985; incidence rates in all other European countries, except France and Denmark, were below 10 in 1,000,000. Subsequently, AIDS incidence has increased more rapidly in southern Europe than in the rest of the continent. The estimated incidence rate for men in Spain (243 in 1,000,000) approached that in the United States (304 in 1,000,000) in 1992, and three additional countries (France, Switzerland and Italy) showed rates above 100 per million. The spread of the AIDS epidemic among women in some southern European countries was faster than in the United States. In Switzerland and Spain the standardized incidence rates in women were higher than in the United States by 1988 and 1992, respectively. CONCLUSIONS: Analysis trends in incidence rates avoids some weaknesses of AIDS statistics based on absolute numbers, and should become one of the standard tools for AIDS surveillance.
OBJECTIVE: Because the etiology of thyroid cancer is not well described, we conducted a pooled analysis of all published case-control studies, as well as two identified unpublished studies. This paper describes the major characteristics of the 14 studies included in the analysis, as well as the statistical methods employed. Four studies were conducted in the United States (1 each in Washington State, California, Connecticut and Hawaii), 8 in Europe (3 in Sweden, 2 in Norway, 1 in Switzerland, 1 in Italy and 1 in Greece), and 2 in Asia (1 in China and 1 in Japan). METHODS: The original datasets were obtained and restructured in a uniform format. Data on socio-demographic characteristics, anthropometric measures, smoking and alcohol consumption, history of benign thyroid diseases and of other selected medical conditions and treatments, family history of cancer and of benign thyroid conditions, occupation, residence in endemic goitre areas, and dietary habits were analyzed. For women, we also analyzed menstrual and reproductive factors and use of female hormones. Radiotherapy and, in Japan, exposure to the A-bombs were considered as potential confounding factors. RESULTS: A total of 2,725 cases (2,247 females and 478 males) and 4,776 controls (3,699 females and 1,077 males) were included in this study. Of the cases, 79% were classified as papillary thyroid carcinomas, 14% as follicular, 2% medullary, 1% anaplastic, 1% other histologies, and 3% histological type unknown. Each of the datasets was checked for outliers and consistency. Data were analysed separately by study center, gender, and the two major histologic types (papillary, follicular). Frequency tables and simple statistics were computed for each variable under study. Conditional logistic regression was used to compute odds ratios. For matched studies, the original matching was preserved, whereas, for unmatched ones, five-year age groups were used for matching. Study-specific analyses were computed, and then the data from all the studies were pooled conditioning on study. Heterogeneity between studies, geographic areas and study designs was assessed, and the modifying effect of age was also evaluated.
OBJECTIVE: To better understand the role of fish and shellfish on thyroid cancer risk, we systematically re-analyzed the original data from 13 case-control studies conducted in the US, Japan, China, and Europe. METHODS: A total of 2497 cases (2023 women, 474 men) and 4337 controls (3268 women, 1069 men) were considered. Odds ratio (OR) and corresponding 95% confidence interval (CI) were estimated for each study by logistic regression models, conditioned on age and sex, and adjusted for history of goiter, thyroid nodules or adenomas, and radiation. Combined ORs were computed as the weighted average of the estimates from each study. RESULTS: The ORs for the highest level of total fish consumption (three or more times per week) as compared to the lowest one (less than once per week) was above unity in Hawaii, Connecticut, Japan, Norway, Tromsø, and Vaud. Conversely, the ORs for the studies in Los Angeles. Shanghai, southeastern Sweden, Uppsala, northern Sweden, northern Italy, and Athens were below one. The pattern of risk for salt water fish and shellfish was not substantially different from that of total fish. Fish was not associated with thyroid cancer risk in all studies combined (OR = 0.99, 95% CI 0.85-1.2 for moderate, and OR=0.88, 95% CI 0.71-1.1 for high total fish consumption), but there was a suggestion of a protective effect in endemic goiter areas (OR = 0.65, 95% CI 0.48-0.88). CONCLUSION: This combined analysis indicates that relatively elevated fish consumption does not appreciably increase thyroid cancer risk, and may have a favorable influence in areas where iodine deficiency is, or was, common.