Analysis of rates from disease registers are often reported inadequately because of too coarse tabulation of data and because of confusion about the mechanics of the age-period-cohort model used for analysis. Rates should be considered as observations in a Lexis diagram, and tabulation a necessary reduction of data, which should be as small as possible, and age, period and cohort should be treated as continuous variables. Reporting should include the absolute level of the rates as part of the age-effects. This paper gives a guide to analysis of rates from a Lexis diagram by the age-period-cohort model. Three aspects are considered separately: (1) tabulation of cases and person-years; (2) modelling of age, period and cohort effects; and (3) parametrization and reporting of the estimated effects. It is argued that most of the confusion in the literature comes from failure to make a clear distinction between these three aspects. A set of recommendations for the practitioner is given and a package for R that implements the recommendations is introduced.

Aims/hypothesis The aim of the study was to describe trends in the incidence rate, prevalence and mortality rate for diabetes in Denmark. Methods Healthcare registers at the National Board of Health were used to compile a register of diabetic patients in the Danish population (5.4 million people). Age-and sex-specific prevalence, incidence rates, mortality rates and standardised mortality ratios relative to the non-diabetic part of the population were calculated. Results The register contains records for about 360,000 persons with diabetes; 230,000 were alive at 1 January 2007, corresponding to an overall prevalence of 4.2%. The prevalence increased by 6% per year. In 2004 the incidence rates were 1.8 per 100,000 at age 40 years and 10.0 per 100,000 at age 70 years. The incidence rate increased 5% per year before 2004 and then stabilised. The mortality rate in the diabetic population decreased 4% per year, compared with 2% per year in the non-diabetic part of the population. The mortality rate decreased 40% during the first 3 years after inclusion in the register. The standardised mortality ratio decreased with age, from 4.0 at age 50 years to 2.5 at age 70 years and just under 2 at age 85 years, identically for men and women. The standardised mortality ratio decreased 1% per calendar year. The lifetime risk of diabetes was 30%. Conclusions/interpretation The prevalence of diabetes in Denmark rose in 1995-2006, but the mortality rate in diabetic patients decreased faster than that of the nondiabetic population. The mortality rate decreased markedly just after inclusion in the register. Incidence rates have shown a tendency to decrease during the last few years, but this finding should be viewed with caution.

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OBJECTIVE -To develop a simple self-administered questionnaire identifying individuals with undiagnosed diabetes with a sensitivity of 75% and minimizing the high-risk group needing subsequent testing. RESULTS -The final risk score included age, sex, BMI, known hypertension, physical activity at leisure time, and family history of diabetes, items independently and significantly (P Ͻ 0.05) associated with the presence of previously undiagnosed diabetes. The area under the receiver operating curve was 0.804 (95% CI 0.765-0.838) for the first half of the Inter99 population, 0.761 (0.720 -0.803) for the second half of the Inter99 population, and 0.803 (0.721-0.876) for the ADDITION pilot study. The sensitivity, specificity, and percentage that needed subsequent testing were 76, 72, and 29%, respectively. The false-negative individuals in the risk score had a lower absolute risk of ischemic heart disease compared with the true-positive individuals (11.3 vs. 20.4%; P Ͻ 0.0001). RESEARCH DESIGN AND METHODSCONCLUSIONS -We developed a questionnaire to be used in a stepwise screening strategy for type 2 diabetes, decreasing the numbers of subsequent tests and thereby possibly minimizing the economical and personal costs of the screening strategy.

Rapid increases in cervical adenocarcinoma incidence have been observed in Western countries in recent decades. Postulated explanations include an increasing specificity of subtype-the capability to diagnose the disease, an inability of cytologic screening to reduce adenocarcinoma, and heterogeneity in cofactors related to persistent human papillomavirus infection. This study examines the possible contribution of these factors in relation with trends observed in Europe. Age-period-cohort models were fitted to cervical adenocarcinoma incidence trends in women ages <75 in 13 European countries. Age-adjusted adenocarcinoma incidence rates increased throughout Europe, the rate of increase ranging from around 0.5% per annum in Denmark, Sweden, and Switzerland to z3% in Finland, Slovakia, and Slovenia.