Understanding recent trends in incidence of invasive breast cancer in Norway: age-period-cohort analysis based on registry data on mammography screening and hormone treatment use.
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ABSTRACT: Objective
To quantify the separate contributions of menopausal hormone treatment and mammography screening activities on trends in incidence of invasive breast cancer between 1987 and 2008.Design
Population study using aggregated data analysed by an extended age-period-cohort model.Setting
Norway. Population Norwegian women aged 30-90 between 1987 and 2008, including 50,102 newly diagnosed cases of invasive breast cancer. Main outcomes measures Attributable proportions of mammography screening and hormone treatment to recent incidence of invasive breast cancer, and the remaining variation in incidence after adjustment for mammography screening and hormone treatment.Results
The incidence of invasive breast cancer in Norway increased steadily until 2002, levelled off, and then declined from 2006. All non-linear changes in incidence were explained by use of hormone treatment and mammography screening activities, with about similar contributions of each factor. In 2002, when the incidence among women aged 50-69 was highest, an estimated 23% of the cases in that age group could be attributed to mammography screening and 27% to use of hormone treatment.Conclusions
Changes in incidence trends of invasive breast cancer since the early 1990s may be fully attributed to mammography screening and hormone treatment, with about similar contributions of each factor.
SUBMITTER: Weedon-Fekjær H
PROVIDER: S-EPMC3268754 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundHip fractures incur the greatest medical costs of any fracture. Valid epidemiological data are important to monitor for time-dependent changes. In Norway, hip fractures are registered in the Norwegian Patient Registry (NPR), but no published national validation exists. The aim of the present study was a national validation of NPR as a register for hip fractures using diagnostic codes (ICD-10 S 72.0-2) and/or procedure codes (NOMESCO version 1.14 NFBxy (x=0-9, y=0-2) or NFJxy (x=0-9, y=0-2).MethodA nationwide, population-based cohort comprising a random sub-sample of 1,000 hip fracture-related entries for the years 2008-09 was drawn from the NPR. 200 entries were defined by a combination of diagnostic and procedure codes (subsample 1), 400 entries were defined by diagnostic codes only (subsample 2) and 400 entries were defined by procedure codes only (subsample 3). Accuracy was ascertained through comparison with discharge summaries, procedure notes and X-ray reports requested from 40 health institutions. Comparisons between groups were done by chi2 for categorical and t-test for continuous variables.Results792 health records from 32 institutions were reviewed. High accuracy (98.2%, 95% C.I. 96.5-99.9%) was found for subsample 1, a combination of diagnostic and procedure codes. Coding errors were prominent in other subsamples. Defining fractures by a combination of diagnostic and procedure codes, annual average hip fracture incidence in Norway was 9,092 (95% C.I. 8,934 -9,249), excluding only 6.5% of all hip fractures defined by wider definitions.ConclusionsBased on current coding practice in Norway, a reliable national estimate of hip fracture incidences is found by a combination of relevant ICD-10 and NOMESCO codes in the NPR. This method may be used for monitoring epidemiological changes.
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Project description:ObjectivesPertussis or whooping cough-one of the most contagious diseases-is caused by the Gram-negative bacterium Bordetella pertussis. Despite a high vaccination rate, Korea recently experienced a resurgence of pertussis. This study explores patterns and possible explanations for this resurgence through an age-period-cohort analysis.MethodsUsing secondary data from the infectious disease portal of the Korea Disease Control and Prevention Agency and the Korea Statistical Information Service of Statistics Korea, this study analyzed the incidence of pertussis in Korea to determine which factors contributed to the recent increase using an age-period-cohort model.ResultsAnalysis of the age effect indicated that the age group most vulnerable to pertussis was 0-year to 2-year-olds. Analysis of the period effect showed a sharp increase in the incidence rate after 2016. Analysis of the cohort effect showed a significant decrease in incidence beginning with the 1955 birth cohort, with the risk increasing again with the 2000s birth cohort.ConclusionsPrevious studies have suggested 3 main possible explanations for our results. First, the increased incidence rate can be attributed to contact rates. Second, the rate of immunity through natural exposure has decreased due to the low number of circulating pathogens, in turn affecting the trend of infection. Lastly, variations in pathogens may have also contributed to the increase in incidence. Given that the most significant increase in incidence was observed among infants younger than 1 year old, sufficient maternal immunity must be prioritized to provide passive immunity to newborns via the placenta.
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Project description:This study used nationwide hip fracture data from Denmark and Sweden during 1987-2010 to examine effects of (birth) cohort and period. We found that time trends, cohort, and period effects were different in the two countries. Results also indicated that hip fracture rates may increase in the not so far future.IntroductionThe reasons for the downturn in hip fracture rates remain largely unclear but circumstances earlier in life seem important.MethodsWe ascertained hip fractures in the populations ≥50 years in Denmark and Sweden in national discharge registers. Country- and sex-specific age-period-cohort (APC) effects during 1987-2010 were evaluated by log-likelihood estimates in Poisson regression models presented as incidence rate ratios (IRR).ResultsThere were 399,596 hip fractures in SE and 248,773 in DK. Age-standardized hip fracture rate was stable in SE men but decreased in SE women and in DK. Combined period + cohort effects were generally stronger in SE than DK and in women than men. IRR per period ranged from 1.05 to 1.30 in SE and 0.95 to 1.21 in DK. IRR per birth cohort ranged from 1.07 to 3.13 in SE and 0.77 to 1.67 in DK. Relative period effects decreased with successive period in SE and described a convex curve in DK. Relative cohort effects increased with successive birth cohort in both countries but with lower risks for DK women and men and SE women born around the 1930s (age 75-86 years today and responsible for most hip fractures) partly explaining the recent downturn. Men and women born thereafter however seem to have a higher hip fracture risk, and we expect a reversal of the present decline in rates, with increasing hip fracture rates in both Denmark and Sweden during the upcoming decade.ConclusionsTime trends, cohort, and period effects were different in SE and DK. This may reflect differences in general health as evident in known differences in life expectancy, healthcare organization, and prevention such as use of anti-osteoporosis drugs. Analyses indicate that hip fracture rates may increase in the not so far future.
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