BACKGROUND Plantar fasciitis is one of the more common soft-tissue disorders of the foot, yet little is known about its etiology. The purpose of the present study was to use an epidemiological design to determine whether risk factors for plantar fasciitis could be identified. Specifically, we examined the risk factors of limited ankle dorsiflexion with the knee extended, obesity, and time spent...

A method of inverse sampling of controls in a matched case-control study is described in which, for each case, controls are sampled until a discordant set is achieved. For a binary exposure, inverse sampling is used to determine the number of controls for each case. When most individuals in a population have the same exposure, standard case-control sampling may result in many case-control sets ...

The aim was to compare the oral health status of patients with eating disorders (EDs), with sex- and age-matched controls, with a view to identify self-reported and clinical parameters that might alert the dental healthcare professional to the possibility of EDs. All patients who entered outpatient treatment in an ED clinic during a 12-month period were invited to participate. Of 65 ED patients...

Multiple control groups in case-control studies are used to control for different sources of confounding. For example, cases can be contrasted with matched controls to adjust for multiple genetic or unknown lifestyle factors and simultaneously contrasted with an unmatched population-based control group. Inclusion of different control groups for a single exposure analysis yields several estimate...

BACKGROUND Acute and recurrent acute urticaria are often associated with multiple factors including infections and recent data suggest a role for herpesviruses. OBJECTIVE To test the null hypothesis, that is, there is no association of herpesvirus infections with urticaria. METHODS Thirty-seven patients between one month and 15 years of age were age matched to 37 controls who were healthy o...

OBJECTIVES The purpose of this study was to compare the results and complications of tibial lengthening over an intramedullary nail with treatment using the traditional Ilizarov method. METHODS In this matched case study, 16 adult patients underwent 19 tibial lengthening over nails (LON) procedures. For the matched case group, 17 patients who underwent 19 Ilizarov tibial lengthenings were ret...

Matched-Molecular Pair (MMP) analysis has recently emerged as a data analysis technique in medicinal chemistry. It quickly gained scientific momentum because it tackles key questions in lead optimization. In contrast to classical global QSAR models that attempt to predict the absolute numbers of ADME (absorption, distribution, metabolism, excretion) and toxicological properties, MMP analyses pr...

In epidemiological studies one is interested in investigating the probability of disease depending on risk factors and in particular in detecting interactions of risk factors. Within the setting of parametric logistic regression interactions can be modeled only in a clumsy and limited way. Modeling the risk function nonparametrically, estimating it e.g. by a smoothing (thin plate) spline is att...

OBJECTIVE To calculate relative powers for nested case-control studies for different values of both relative risk and numbers of controls per case, given a fixed number of cases available for analysis. METHODS Algebraic and numerical methods. RESULTS In nested case-control studies, statistical power is a function of relative risk, rarity of exposure, number of case-control sets, and the num...

We develop semiparametric methods for matched case-control studies using regression splines. Three methods are developed: 1) an approximate cross-validation scheme to estimate the smoothing parameter inherent in regression splines, as well as 2) Monte Carlo expectation maximization (MCEM) and 3) Bayesian methods to fit the regression spline model. We compare the approximate cross-validation app...