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...

The paper considers the problem of modelling association between two exposure variables in a matched case-control study, where both the exposures may be partially missing. The exposure variables could all be categorical or continuous or could be a mixed set of some categorical and some continuous variables. Association models for the missing exposure variables using the completely observed cova...

background: headaches are one of the most frequent reasons for pain in multiple sclerosis (ms) individuals. characterization of headaches and delineating possible relationships with ms-related determinants can ultimately circumvent headaches. methods: in a prospective case-control study, 65 iranian relapsing- remitting ms (rrms) patients and 65 healthy controls were recruited during patients’ a...

background: the aim of this study was to investigate the relationship between congenital hypothyroidism and several variables using two different adjustment methods. methods: this matched case-control study was conducted in hamadan province, the west of iran, in 2012 enrolling neonates born between 2005 and 2011 and covered by screening program for congenital hypothyroidism. the neonates with t...

background certain social determinants may influence host susceptibility to tuberculosis (tb) infections, and increase the risk of developing the disease. objectives the present study aimed to evaluate the effects of several host and environmental factors on the risk of tb in northern iranian households. patients and methods this case-control study was conducted for one year between 2010 and 20...

patients and methods fifty nine patients with indication for carpal tunnel release randomly assigned into two groups: open (n=30) or knifelight (n=29). the patients compared regarding scar length, operation duration, time to return to daily activities and amount of pain at three weeks after operation based on visual analog scale. results there was no significant differences regarding age and se...

prostate cancer is a major cause of morbidity and mortality in iran, yet there are few studies examining risk factors specific to the iranian context. we conducted a case-control study to explore risk factors for prostate cancer in mazandaran, iran from 2005 to 2008. the cases were 137 men with clinicopathologically confirmed prostate cancer. controls were 137 neighborhood and age match men wit...