Estimation and Projection of Indicence and Prevalence Based on Doubly Truncated Data with Application to Pharmacoepidemiological Databases

Incidences of disease are of primary interest in any epidemiological analysis of disease spread in general populations. Ordinary estimates obtained from follow-up of an initially non-diseased cohort are costly, and so such estimates are not routinely available. In contrast, routine registers exist for many diseases with data on all detected cases within a given calendar time period, but lacking information on non-diseased. In the present work we show how this type of data supplemented with data on the past birth process can be analyzed to yield age specific incidence estimates as well as lifetime prevalence. A non-parametric model is studied with emphasis on the required assumptions, and a brief outlook on the analysis of the non-stationary case with calendar trends in age-specific incidence is given. The developed methods are applied to case cohort data on treatment with anti-diabetic medications and projections are provided for both diabetes incidence and prevalence. As projection of diabetes prevalence requires estimation of the distribution of disease durations, two novel approaches for this estimation is studied, a parametric and a non-parametric, respectively

Scandinavian trial of uncomplicated aortic dissection therapy : study protocol for a randomized controlled trial

Peer reviewe

Incidence, mortality and relative survival of patients with cancer of the bladder and upper urothelial tract in the Nordic countries between 1990 and 2019

PurposeTo understand the potential impact of new treatment options for urinary tract cancer, recent population trends in incidence, mortality and survival should be elucidated. This study estimated changes in the incidence, mortality and relative survival of urinary tract cancer in the Nordic countries (Denmark, Finland, Iceland, Norway and Sweden) between 1990 and 2019.MethodsAnnual counts of incident cases and deaths due to urinary tract cancer (International Classification of Diseases, Tenth Revision, Clinical Modification codes C65-C68, D09.0-D09.1, D30.1-D30.9 and D41.1-D41.9) in Nordic countries were retrieved in 5-year age categories by sex during the study period. Country-specific time trends (annual rate ratios [RRs]) were estimated using Poisson regression, and RRs were compared between sexes.ResultsThe incidence rate of bladder and upper urothelial tract cancer was >3-times lower in women than men in all countries across all age groups (incidence RR for women to men ranging from 0.219 [95% CI = 0.213-0.224] in Finland to 0.291 [95% CI = 0.286-0.296] in Denmark). Incidence rates were lowest in Finland and highest in Norway and Denmark. Age-adjusted mortality decreased in Finland, Denmark and Norway and in Swedish men, with the greatest decrease seen in Danish men (annual RR = 0.976; 95% CI = 0.975-0.978). In all countries and age groups, women had a lower relative survival rate than men.ConclusionBetween 1990 and 2019, the incidence of urinary tract cancer was stable in the Nordic countries, while mortality rates declined and relative survival increased. This could be due to earlier diagnosis and better treatment.Peer reviewe

Communicating effectiveness of intervention for chronic diseases: what single format can replace comprehensive information?

<p>Abstract</p> <p>Background</p> <p>There is uncertainty about how GPs should convey information about treatment effectiveness to their patients in the context of cardiovascular disease. Hence we study the concordance of decisions based on one of four single information formats for treatment effectiveness with subsequent decisions based on all four formats combined with a pictorial representation.</p> <p>Methods</p> <p>A randomized study comprising 1,169 subjects aged 40–59 in Odense, Denmark. Subjects were randomized to receive information in terms of absolute risk reduction (ARR), relative risk reduction (RRR), number needed to treat (NNT), or prolongation of life (POL) without heart attack, and were asked whether they would consent to treatment. Subsequently the same information was conveyed with all four formats jointly accompanied by a pictorial presentation of treatment effectiveness. Again, subjects should consider consent to treatment.</p> <p>Results</p> <p>After being informed about all four formats, 52%–79% of the respondents consented to treatment, depending on level of effectiveness and initial information format. Overall, ARR gave highest concordance, 94% (95% confidence interval (91%; 97%)) between initial and final decision, but ARR was not statistically superior to the other formats.</p> <p>Conclusion</p> <p>Decisions based on ARR had the best concordance with decisions based on all four formats and pictorial representation, but the difference in concordance between the four formats was small, and it is unclear whether respondents fully understood the information they received.</p

Can differences in medical drug compliance between European countries be explained by social factors: analyses based on data from the European Social Survey, round 2

<p>Abstract</p> <p>Background</p> <p>Non-compliance with medication is a major health problem. Cultural differences may explain different compliance patterns. The size of the compliance burden and the impact of socio-demographic and socio-economic status within and across countries in Europe have, however, never been analysed in one survey. The aim of this study was to analyse 1) medical drug compliance in different European countries with respect to socio-demographic and socio-economic factors, and to examine 2) whether cross-national differences could be explained by these factors.</p> <p>Methods</p> <p>A multi-country interview survey <it>European Social Survey, Round 2 </it>was conducted in 2004/05 comprising questions about compliance with last prescribed drug. Non-compliance was classified as primary and secondary, depending whether the drug was purchased or not. Statistical weighting allowed for adjustment for national differences in sample mechanisms. A multiple imputation strategy was used to compensate for missing values. The analytical approach included multivariate and multilevel analyses.</p> <p>Results</p> <p>The survey comprised 45,678 participants. Response rate was 62.5% (range 43.6–79.1%). Reported compliance was generally high (82%) but the pattern of non-compliance showed large variation between countries. Some 3.2% did not purchase the most recently prescribed medicine, and 13.6% did not take the medicine as prescribed. Multiple regression analyses showed that each variable had very different and in some cases opposite impact on compliance within countries. The multilevel analysis showed that the variation between countries did not change significantly when adjusted for increasing numbers of covariates.</p> <p>Conclusion</p> <p>Reported compliance was generally high but showed wide variation between countries. Cross-national differences could, however, not be explained by the socio-demographic and socio-economic variables measured.</p

A generic function evaluator implemented in Mata

Background : When implementing new statistical procedures, there is often a need for simple—and yet computationally efficient—ways of numerically evaluating composite distribution functions. If the statistical procedure must support calculations for censored and noncensored cases, those calculations should be carried out using efficient computational implementations of both definite and indefinite integrals (e.g., calculation of tail areas of distribution functions). Method : We developed a generic function evaluator such that users may specify a function using reverse Polish notation. As its argument the function evaluator takes a matrix of pointers and then applies the rows of this matrix to its internally defined stack of pointers. Accordingly, each row of the argument matrix defines a single operation such as evaluating a function on the current element of the stack, applying an algebraic operation to the two top elements of the stack, or manipulating the stack itself. Defining new composite distribution functions from other (atomic) distribution functions then corresponds to joining two or more function-defining matrices vertically. This approach can further be used to obtain integrals of any defined function. As an example we show how the density and distribution function for the minimum of two Weibull distributed random variables can be numerically evaluated and integrated. Results : The procedure provides a flexible and extensible framework for implementing numerical evaluation of general, composite distributions. The procedure is numerically relatively efficient, although not optimal

A generic function evaluator implemented in Mata

When implementing new statistical procedures, there is often a need for simple--and yet computationally efficient--ways of numerically evaluating composite distribution functions. If the statistical procedure must support calculations for censored and noncensored cases, those calculations should be carried out using efficient computational implementations of both definite and indefinite integrals (e.g., calculation of tail areas of distribution functions). We developed a generic function evaluator such that users may specify a function using reverse Polish notation. As its argument the function evaluator takes a matrix of pointers and then applies the rows of this matrix to its internally defined stack of pointers. Accordingly, each row of the argument matrix defines a single operation such as evaluating a function on the current element of the stack, applying an algebraic operation to the two top elements of the stack, or manipulating the stack itself. Defining new composite distribution functions from other (atomic) distribution functions then corresponds to joining two or more function-defining matrices vertically. This approach can further be used to obtain integrals of any defined function. As an example we show how the density and distribution function for the minimum of two Weibull distributed random variables can be numerically evaluated and integrated. The procedure provides a flexible and extensible framework for imple- menting numerical evaluation of general, composite distributions. The procedure is numerically relatively efficient, although not optimal. Copyright 2007 by StataCorp LP.rpnfcn(), RPN, Mata

ZIPSAVE: Stata module to save and use datasets compressed by zip

this module allows you to save and use datasets compressed by zip on WindowsXP/Unix/Linux/Macintosh in order to save disk space and network load. Shares syntax with Stata's -save-, -saveold- and -use- commands.zip, compression, save, use

EVHISTPLOT: Stata module to produce event history plot

this module plots event histories for one or more variables holding one or more types of events. As an option Lexis-diagrams can be produced.event history, plot, Lexis diagram

WTD: Stata module to produce analysis of waiting time distribution

The term wtd refers to Waiting Time Distribution data and the commands for analyzing them, all of which begins with the letters wtd. For a description of the Waiting Time Distribution concept, please refer to Støvring and Vach (2005). Estimation of prevalence and incidence based on occurrence of health-related events, Statistics in Medicine. In short, the concept of the Waiting Time Distribution allows estimation of incidence and prevalence of for example drug use, based exclusively on occurrence of health-related events, in this case individual drug redemptions from pharmacies. Another example is incidence and prevalence of hypertension treatment based on occurrence of hypertension related consultations with physicians.waiting time distribution, prevalence, incidence